KEYWORDS: Vegetation, Air contamination, Climatology, MODIS, Air temperature, Climate change, Land cover, Environmental monitoring, Satellites, Temperature metrology
In frame of the global warming and urban growth, Bucharest residents and its ecosystem will be more vulnerable to increased levels of air pollution and heat stress related to urban heat island (UHI) effect and the increased frequency and duration of heat waves (HWs) during summer June-August months. The response of air quality to climate change is an increasing concern at both the local and global levels. This study examined the response of urban thermal environment to air pollution and climate variability in Bucharest, Romania, from a spatiotemporal perspective during the 2020-2023 period. Through synergy use of time series of geospatial and in-situ air pollution (particulate matter PM2.5 and PM10, O3, NO2, SO2, CO), and climate data in relation with derived vegetation biophysical variables, this study developed a complex statistical and spatial regression analysis. Was quantified air pollution relationship with urban thermal environment defined by land surface temperature-LST and air temperature at 2m height AT. Green space was measured with MODIS Terra satellite-derived normalized vegetation index- NDVI, which captures the combined availability of urban parks, street trees, forest, and periurban agricultural areas. A distinct spatiotemporal difference across the urban/periurban gradient, air temperature -TA and land surface temperature -LST anomalies is associated with urbanization-induced climate warming, especially during summer UHIs and HWs. The findings of this study contribute to developing advanced models to predict air pollution impacts on urban heat under future urbanization, and also in urban planning for better mitigation and optimizing air quality in future green cities.
Rapid urbanization exacerbates spatiotemporal changes of urban surface albedo, an essential biophysical variable in surface energy balance and the health risks of climate warming. Through statistical and spatial regression analysis of the time series MODIS Terra/Aqua and in-situ monitoring data of climate variables for both central city and metropolitan area, this study identified the impact of urban built in Bucharest metropolitan area on spatiotemporal variation of land surface albedo (LSA) during 2002- 2023 period, and quantified its relationship with urban thermal environment (land surface temperature-LST and air temperature at 2m height AT) and associated vegetation (normalized vegetation index– NDVI, leaf area index-LAI, evapotranspiration-ET) and other climate factors. During summer hot periods, this study found a strong inverse correlation between LSA and LST (r= -0.85; p<0.01) in all city sectors explaining high negative impact on the urban thermal environment. Also, as a measure of urban surface thermal properties, land surface albedo depends on the atmospheric conditions. At the pixel-scale, during the summer season (June-August) air temperature at 2m height AT is positively correlated with LST (r= 0.86%, p<0.01). For summer periods (June – August), LST shows an inverse correlation with NDVI for both central Bucharest city (r= -0.29, p< 0.01) and for metropolitan area (r= -0.67, p<0.01). Because urban climate system is highly sensitive to land surface albedo changes, urban/periurban vegetation land covers may have strong feedback to the anticipated climate warming. Future climate adaptation strategies must consider albedo cooling benefits and urban greening that can reduce the heat exposure of urban populations.
In frame of global warming context impact arid regions are affected by increases in temperature and decreases in precipitation, that will trigger water shortages, drought, and further aridification. This paper addresses a number of issues related to current and future climatic change and drought impacts on vegetation land cover, focusing on the Constanta County in Dobrogea region placed in the South Eastern part of Romania near North Western Black Sea coastal area. Remotely sensed monitoring and assessing of drought effects in long term change could provide sound understanding to guide arid agricultural areas ecological restoration and local ecosystem sustainability. This study examined the applicability of MODIS Terra/Aqua time series satellite-based together MERRA -2 reanalysis data in synergy with insitu monitoring of climate observables for aridity assessment. Time series of Normalized Difference Vegetation Index - NDVI, evapotranspiration-ET, land surface albedo-LSA, land surface temperature-LST and air surface temperature-AT at different time scales and other climate parameters (precipitation rate, relative humidity and surface solar irradiance-SI were computed for the period 2000 to 2023. The trend analysis of the time series for ET, NDVI and LST in the Constanta Cunty was conducted using a simple linear regression analysis method. During summer periods (June – August) of 2021-2023 period, LST and NDVI appeared to be linear and negatively correlated in each year ranged from r = - 0.85 with p<0.05 in 2022 year, r = - 0.77 with p<0.05 in 2021 year, and r = - 0.40 with p<0.05 in 2023 year. A high decrease of NDVI values ranged (0.2-0.3) was recorded during summer-autumn droughts periods of years 2022 and 2023 associated with strong heat waves. The results in this study show that large area of Constanta County is highly controlled by drought during summer to autumn seasons. This work demonstrates the importance of satellite remote sensing data conjugated with in-situ data for changes monitoring of dryland vegetation in their response to climate-drying conditions.
The Vrancea zone in Romania located at the bending of the South-Eastern Carpathians is one of the high-risk seismic zones in Europe, characterized by high occurrence of intermediate-depth earthquakes, confined in a 60–200 km depth lithospheric volume. For continuously surveillance of Vrancea seismic active area in Romania, this study developed and implemented an advanced integrated methodology of multi-field time series satellite- and ground-based observational data of seismic precursors and lithosphere-atmosphere coupling modelling, for new seismic increased activity indicators design. Based on the seismic records in synergy with atmospheric and land surface pre-seismic anomalies detection from Land Surface Temperature (LST) from the time series MODIS Terra/Aqua and NOAA AVHRR along with Air Temperature (AT), this study found significant correlations with moderate seismic events of moment magnitude Mw ≥ 5 on Richter scale for 2012-2023 period. The findings of this study aim to improve, by cross-validating, the methodologies for seismic hazard assessment in Romania due to Vrancea source and detect preparatory seismic phases and precursors. Early detection and monitoring of induced geophysical anomalies can help the decision makers in mitigating the impact and improve disaster response efforts. By this, will contribute at promoting an EOS for Romania in frame of ESA Copernicus. The investigation of the seismo-associated phenomena from space is a challenge for Earth Observation and earthquake forecasting, having a high impact on the seismicity monitoring for SDGs as well for Natural Hazard Directive in the EU.
KEYWORDS: MODIS, Climatology, Vegetation, Land cover, Climate change, Satellites, Temperature metrology, Surface air temperature, Near infrared, Ecosystems
Spatial change in the urban landscape related to land cover conversion due to urbanization is recognized as the critical factor affecting the formation and intensity of Urban Heat Island (UHI), which under summer Heat Waves (HWs) substantially modifies the land surface-aerodynamic properties, the energy and water balances and urban thermal environment. One of the most important goals of satellite-based urban thermal environment investigations is the better understanding of the physical content of different satellite-derived biophysical parameters. The specific object of this study is to use time-series Landsat TM/ETM+ and MODIS Terra/Aqua satellite data for assessing of urban land cover– air and land surface temperature interactions during period between 2000 and 2022 years over Bucharest metropolitan area. The air (TA) and Land Surface Temperature (LST), key parameters in urban climate research are analyzed in relation with land surface albedo and Normalized Difference Vegetation Index (NDVI) variables and quantified the spatiotemporal cooling effects of urban green landscape characteristics impacts on urban thermal environment dynamic at city level. The rank correlation analyses revealed that, at the pixel-scale, during summer season (June-August) TA and LST presents a strong positive correlation (r= 0.86%, p⪅0.01). During summer periods (June – August), LST-NDVI shows a negative correlation (for central city areal r= -0.23, p⪅ 0.05; and for metropolis areal r= -0.67, p⪅;0.01). Also, the monthly mean UHI intensity belongs to the range of (1.3 oC to 6.5 oC), and the most intense UHI occurs during the day-time in the summer season in synergy with heat waves periods. Several urban/periurban zones and landscapes bring diurnally and seasonally different contributions to the local and regional thermal environment.
Urban/periurban forest, sensitive to climatic factors with different vulnerability thresholds according to the species, amplitude, and rate of climatic stressors plays a critical function in the urban microclimate, mitigating air pollution. Use of urban forest-derived satellite variables is essential for understanding its spatiotemporal changes. To address this issue, we applied time series analysis of MODIS Terra, Landsat TM/ETM+/OLI, and Sentinel-2 data, to assess spatiotemporal changes of the periurban forest Cernica-Branesti system, located in the Eastern part of Bucharest city in Romania, from the perspective of vegetation phenology and its relation with climate changes and extreme climate events during 2002- 2022 period. To evaluate the impacts of climate and anthropogenic stressors on the forest properties, a set of biophysical variables have been estimated and several classifications of forest vegetation over the tested areas have been done. Time series of MODIS satellite-derived Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), Land Surface Temperature (LST), Leaf Area Index (LAI), and Evapotranspiration (ET), together in-situ climate variables were analyzed through anomaly detection techniques, and correlations between them were computed. Temperature, rainfall and solar irradiance were significantly correlated with land-cover classes. Annual change detection rates across the investigated forest area over the study period were estimated at 0.82 % per annum in the range of 0.47% (2002) to 0.93% (2022). This study found that vegetation indices NDVI/EVI in Cernica-Branesti periurban forest are inversely correlated with LST during summer season and positively correlated with LST during autumn, winter and spring seasons. Also, NDVI/EVI are positively correlated with LAI and ET during entire investigated period.
Urban vegetation and its carbon storage capacity are critical factors for terrestrial carbon cycling and global Sustainable Development Goals (SDGs). Scientific research for a better managing of urban green land cover is an essential issue of the sustainable urban development initiative promoted by the EU governments. Owing to a crucial role that urban vegetation performs in an urban ecosystem, being effective in mitigating the air pollution and urban heat island effect by canopy shade and evapotranspiration, studying the vegetation dynamics in terms of its derived satellite biogeophysical variables becomes inevitable in the context of climate-smart city planning and design. However, in order to explain the urban-rural gradient in vegetation greenness trends and its responses to climate and antropogenic drivers of land-cover changes this study used time-series of derived satellite data (normalized difference vegetation index-NDVI, enhanced vegetation index- EVI, land surface temperature- LST, leaf area index LAI, and fraction of photosynthetically active radiation absorbed by vegetation- FPAR). Satellite datasets of MODIS Terra, and Landsat TM/ETM+ have been used for urban vegetation analysis over 2002-2022 period of Bucharest metropolitan area in Romania. It was found that the average decrease in vegetation land cover was 0.1 to 0.3. The correlation analyses revealed that, at the pixel-scale, LST possessed a strong positive correlation with NDVI, EVI, FPAR and LAI during the entire investigated period. Only during summer period NDNI/EVI are inversely correlated with LST (r= -0.67; p<0.01) The spatio-temporal pattern of urban/periurban vegetation dynamics trends and their association with other atmospheric, biological, and soil indicators need to be studied with different satellite sensors and resolutions over the long-term periods of time.
KEYWORDS: COVID 19, Climatology, Air contamination, Meteorology, Carbon monoxide, Diseases and disorders, Climate change, Air temperature, Air quality, Aerosols
As a global public health concern for almost three years, Coronavirus Disease 2019 (COVID-19) caused by different strains of severe acute respiratory syndrome coronavirus two (SARS-CoV-2), and the transmission characteristics vary among counties, regions and virus variants. This paper investigates the synergy between the changes in the exposure to the main outdoor air pollutants (particulate matter PM2.5 and PM10, NO2, SO2, CO, and O3), and meteorological-related factors, which may exacerbate the SARS-CoV-2 viral effect on human health and the COVID-19 incidence and lethality in Bucharest. Through applied statistical analyses of average daily in-situ and satellite time series data recorded during several seasons and over a long time period (1 March 2020-1 April 2022), during five COVID-19 pandemic waves, this study provides an accurate estimation of the local and regional mutual seasonality of the air quality and epidemiologic conditions impacts of the COVID-19 disease evolution in Bucharest metropolitan city. This study found a positive correlation between the main air pollutants (PM2.5, PM10; NO2, CO and SO2) and confirmed cases of COVID-19 caused by different SARS-CoV-2 strains. An opposite correlation was found for at the ground level ozone-O3. In spite of spring 2020 total lockdown, or other restriction periods associated with the COVID-19 waves, aerosol loading over Bucharest metropolis did not record significant reduction in comparison with the pre-pandemic period. This study could provide valuable information into epidemic viral diseases control strategies to limit urban air pollution, especially during synoptic anticyclonic active systems.
During last decade, due to fast progress of geospatial technology development, all weather, high-resolution and highdynamic range, a huge time-series data base is available for earthquake precursors anomalies monitoring in active geotectonic areas. In this paper, changes before and after the Vrancea earthquakes in the crustal dynamics as well as in the land and atmospheric parameters (land surface temperature LST, surface latent heat flux -SLHF, and air surface temperature- AT anomalies, have been investigated on the basis of time-series geospatial (NOAA AVHRR and MODIS Terra/Aqua) and field data analysis for January 2012- January 2020 period. For some analyzed earthquakes, starting with ten days up to one week prior to a moderate or earthquakes a transient thermal infrared rise appeared in LST (5-10 K° ), SLHF (tens of W/m2 ), and AT (2-10 C° ) values higher than the normal, function of the magnitude and focal depth, which disappeared after the main shock. The joint analysis of geospatial, geophysical, and geological information revealed new insights for Vrancea zone seismicity in Romania. Since the variations of the solar and geomagnetic indices follow a normal behavior during the whole period of the observed anomalies between 3 and 10 days before the earthquake, it can be concluded that multi-precursors analysis is very important to detect the possible Lithosphere Atmosphere Ionosphere Coupling (LAIC) effects.
This paper aims to investigate the influences of urban growth and green land cover decrease on land surface radiative properties and metropolitan climate of Bucharest in Romania. Remote sensing data from Landsat TM/ETM/OLI, Sentinel 2 and time series MODIS Terra/Aqua thermal infrared sensors as well as in-situ meteorological data have been used to assess urban land cover– air and land surface temperature interactions over period between 2000 and 2019 years. The air (Ta) and land surface temperature (Ts), key parameters for urban climate research, were analyzed in relation with variables land surface albedo and Normalized Difference Vegetation Index (NDVI) at city level. Based on these parameters, the urban growth, Urban Heat Island (UHI) effect and the relationships of Ts to other biogeophysical parameters have been analyzed. The correlation analyses revealed that, at the pixel-scale, Ta and Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. Was also analyzed UHI phenomenon during extreme heat waves events. Our results suggest that monthly mean UHI intensity is between 1°C and 6°C, and the most intense UHI occurs in day-time in the summer period during heat waves periods. The analysis shows that different urban/periurban zones and landscapes bring diurnally and seasonally different contributions to the local and regional thermal environment. City land cover was the most important contributor to increases in regional Ts. Vegetation had a clear cooling effect as the normalized vegetation difference index (NDVI) increased during summer periods.
Understanding how urban forest land cover responds to climate change requires knowledge of land-surface interaction processes, which control the degree to which interannual variability and mean trends in climatic variables affect the surface energy budget and by this forest vegetation. Urban forest represents unique areas for the detection of climatic change and the assessment of climate-related impacts. Effects of climate extremes and anthropogenic changes on urban/periurban forest systems in Romania can have both short-term and long-term implications for standing biomass, tree health and species composition. This paper used time series of normalized difference of vegetation index (NDVI) and enhanced vegetation index (EVI) as well as leaf area index (LAI) as a measurement indicators of forest dynamics at metropolitan scale in order to assess impacts of climate changes on forest ecosystem phenology in metropolitan area of Bucharest. Use of satellite remote sensing to monitor the forest changes due to climatic stressors is an excellent example of the value of multispectral, multiresolution and multitemporal observations. Fusion technique was applied to time series satellite imagery data (Landsat TM/ETM/OLI, Sentinel 2 and MODIS Terra/Aqua satellite data) for urban/periurban forest ecosystem of Bucharest metropolitan area in Romania over 2000-2019 period. Also, this paper addresses a number of issues related to changes in land surface temperature (LST), and analyses correlations between NDVI/EVI time series and climatic variables under different scenarios for summer heat waves, windstorms and heavy precipitation.
Climate changes and rapid urbanization are the main factors affecting forest vegetation land cover around the globe. Satellite remote sensing data provide important information to detect changes in forest landscapes over long time periods in contrast to conventional approaches. Satellite remote sensing provides a useful tool to capture the temporal dynamics of forest vegetation change in response to climate shifts, at spatial resolutions fine enough to capture the spatial heterogeneity. In this paper, we present an integrated, standardized approach that aims at combining remote sensing data provided by different sensors, available for a long-term period (2000-2018). This multi-sensor and multi-temporal approach detects Cernica-Branesti periurban forest vegetation dynamics based on derived biophysical parameters within the highly dynamic city of Bucharest, as a test case. Landsat TM/ETM/OLI, MODIS Terra/Aqua, and Sentinel 2 data are combined in an integrated procedure to locate forest disturbances in relation with potential climate and anthropogenic drivers. To apply the approach for detecting forest land cover changes, the MODIS Normalized Difference Vegetation Index/Enhanced Vegetation Index (NDVI/EVI), and Leaf Area Index (LAI) data are used to provide forest vegetation change detection information in relation with land surface temperature (LST) and climate stressors and to monitor forest vegetation phenological variations. Correlations between NDVI/EVI time series and climatic variables were computed. Forest vegetation dynamics at seasonal and longer timescales reflect large-scale interactions between the terrestrial biosphere and the climate system.
The main problem for seismic precursors recognition is to extract useful information associated with tectonic activities and to eliminate the effects of non-tectonic factors. Pre-earthquake spatio-temporal developed geophysical, geodetically, and geochemical anomalies are controlled by various factors like as earthquake moment magnitude and its focal depth, geological setting, topography, land covers as well as climate and atmospheric conditions. In this paper, changes before and after some moderate Vrancea earthquakes in the crustal dynamics as well as in the land and atmospheric parameters (surface air temperature- AT and land surface temperature LST anomalies, have been investigated on the basis of timeseries geospatial (NOAA AVHRR and MODIS Terra/Aqua) and field data analysis for 2010-2018 period. Ground surface deformations have been detected through analysis of Synthetic Aperture Radar Interferometry (InSAR) radar satellite Sentinel 1 and high quality in-situ GPS monitoring data. The detected changes show strong evidence of coupling between lithosphere-land surface-atmosphere-ionosphere associated with the Vrancea’s earthquakes For some analyzed earthquakes, starting with ten days up to one week prior to a moderate earthquake a transient thermal infrared rise appeared in AT (2-10°C) and LST (20-30°K) higher than the normal values, function of the magnitude and focal depth, which disappeared after the main shock. Ground vertical surface displacements presented on interferometric deformation map are in the range of 4 cm for uplifts and subsidence. The joint analysis of geospatial, geophysical, and geological information is revealing new insights for Vrancea zone seismicity understanding.
In order to quantify the eff ect of urbanization and land cover changes on urban surface albedo change and radiative forcing impact on urban thermal environment MODIS land surface albedo (LSA) and land surface temperature (LST) products were used to investigate the magnitude of extreme climate and anthropogenic pressures. The main goal of this study was to develop an effective remote sensing-based methodological approach to investigate the possible occurrence and associated causes of gradual surface albedo trends in metropolitan area of Bucharest during 2000-2018 period. During summer time and heat waves periods urban land surface broadband albedo is a critical variable affecting Bucharest city climate. Analysis of time series MODIS Terra/Aqua data revealed the strong inverse relationship between LSA and LST during summer time in city area with negative impact on urban thermal environment. Broadband albedo, which measures urban surface properties depends also on the atmospheric conditions. In this study, were analyzed also the interannual variations in Urban Heat Island Intensity (UHI), derived from MODIS LST data and their relationships with vegetation urban indices NDVI/EVI, climate variability and urbanization. These findings stress the dependence of urban thermal environment of urban biogeophysical variables such as land surface albedo, urban density and morphology, surface properties, vegetation, bodies of water, industrial sites, transportation systems and infrastructures.
This paper investigated the influences of urban growth on thermal environment in relationship with other biophysical variables for Bucharest and Timisoara cities in Romania. Satellite remote sensing provides a cost-effective and time-saving methodology for spatio-temporal analyses of land surface temperature (Ts) distribution and urban thermal environment monitoring. Time series satellite remote sensing data from Landsat TM/ETM+/OLI, MODIS Terra/Aqua and NOAA AVHRR were used to assess urban vegetation land cover– temperature interactions over period between 2000 and 2018 years. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban growth. For this purpose, a set of meteorological and climatic data recorded in synoptic stations were used. The land surface temperature (Ts), a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) at city level. Based on these parameters, the urban growth, and urban heat island effect (UHI) and the relationships of Ts to other biophysical parameters have been analyzed. Results show that the city area ratio of impervious surface in both towns Bucharest and Timisoara increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively.
The earth crust suffers a variety of geophysical changes, which produce presignals of impending earthquakes. The coupling model lithosphere–surfacesphere-atmosphere–ionosphere provides a comprehensive mechanism to explain key involved geophysical processes. Space-time anomalies of several seismic precursors detected in multitemporal and multiresolution satellite data or in situ monitoring of radon gas emitted from soil near the ground air weeks to days in the Vrancea epicentral area can be associated with the strain stress changes that occurred before the occurrence of moderate and strong earthquakes. This paper investigated seismic precursors during 2012-2017 period over Vrancea seismogenic region in Romania through analysis of NOAA AVHRR and MODIS Terra/Aqua Thermal Infrared data of key geophysical parameters (Land Surface Temperature -LST, and Air Temperature AT) and atmospheric radon concentration recorded at Plostina seismic station in Vrancea zone and Bucharest using solid state nuclear track detectors (SSNTD) CR-39 radon monitors before some moderate earthquakes. Multi-parameter data have been computed based on multi-year background data for anomalies detection. Results indicate significant transient variations in observed parameters before the main events. Space-time anomalies of several seismic precursors detected in time series satellite data or in situ monitoring of radon gas emitted from soil near the ground air weeks to days in the Vrancea epicentral area can be associated with the strain stress changes that occurred before the occurrence of moderate and strong earthquakes. This research is valuable for identifying earthquake presignals in earthquake prone areas.
This paper investigated urban growth and green land cover decrease impacts on Bucharest metropolitan climate. Time series of Landsat TM/ETM/OLI, MODIS Terra/Aqua and NOAA AVHRR thermal infrared data as well as in-situ meteorological data have been used to assess urban land cover– air and land surface temperature interactions over 2000- 2018 period. The air (Ta) and land surface temperature (Ts), key parameters for urban climate study were analyzed in relation with the Normalized Difference Vegetation Index (NDVI) and surface latent heat flux (SLHF) at city level. Based on these parameters, the urban growth, Urban Heat Island (UHI) effect and the relationships of Ts to other biogeophysical parameters have been investigated. Correlation analysis revealed that, at the pixel-scale, Ta and Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. Was also analyzed UHI phenomenon during extreme heat waves events. Our results suggest that the most intense UHI occurs in day-time in the summer period during heat waves periods. Satellite data in synergy with insitu data revealed a clear land surface temperature contrast between the central, median and peripheral zones of Bucharest metropolitan zone in Romania. The analysis shows that different urban/periurban zones and landscapes bring diurnally and seasonally different contributions to the local and regional thermal environment. Urban land cover was the most important contributor to increases in regional Ts. Vegetation had a clear cooling effect as the normalized vegetation difference index (NDVI) increased during summer periods.
Due to global warming and climate changes forest ecosystems in Romania experienced environmental degradation. Climate models scenaria evidenced that some of the most severe weather events could become more frequent in Romania over the next 50 to 100 years. In the case of Carpathian mountain forests, winter storms, heavy rains, summer draughts and heat waves are considered main keys of climate risks, particularly in prealpine and alpine areas. Forest phenology is a multi-scale phenomenon, arising from processes in leaves and trees, which controls carbon and water cycles, observable at the ecosystem scale (e.g. eddy flux measurements), very important to characterize the relation between phenophase transition events at different spatial scales. Through time series of the Normalized Difference Vegetation Index (NDVI), provided by MODIS Terra/Aqua data is possible to examine trends and seasonality in forest vegetation Leaf Area Index (LAI) and in primary productivity, as well as to identify the impacts of human disturbances (clearcutting, etc.). In order to extract forest phenological changes, this paper applied fusion technique to multitemporal satellite imagery data (Landsat TM/ETM/OLI, Sentinel 2 and MODIS Terra/Aqua satellite data) for a mountain forest ecosystem placed in Prahova Valley, South Carpathians in Romania over 2000-2018 period. Effects of climate extremes on forests can have both short-term and long-term implications for standing biomass, tree health and species composition. The preservation and enhancement of mountain forest vegetation cover in natural, semi-natural forestry ecosystems is an essential factor in sustaining environmental health and averting natural hazards.
The amorphous films show many physical properties which differ from the crystalline state. One of these is the optical transparency photoinduced by light with photon energies higher than optical bandgap. The phenomenon is especially large in amorphous chalcogenide films. However, the changes of optical constants are too small for optoelectronic applications. In this paper we consider structure were the amorphous As2S3 film is placed in a structure which forms a surface plasmon resonance structure. The reflected light is coupled with waveguide modes. The experimental studies show that high nonlinear changes may be achieved for the light intensity of 10- 12 mW when the incident angle is close to resonance. For some film thicknesses the SPR resonance was achieved with prism made from BK7 glass, which is important opportunity for applications.
Sustaining forest resources in Romania requires a better understanding of forest ecosystem processes, and how management decisions and climate and anthropogenic change may affect these processes in the future. This paper aims to provide an application of time series anomalies and harmonic analysis to extract information about vegetation phenology from NDVI/EVI and LAI time series for a forest ecosystem Prahova Valley, placed in Carpathian Mountains, Romania, from MODIS Terra/Aqua data over 2000 – 2017 period. Spatio-temporal forest vegetation dynamics have been quantified also based on LANDSAT TM/ETM/OLI satellite data. Several daily climatic variables, were used as explanatory variables for the discussion of the vegetation phenology behavior. For investigated test area, considerable NDVI/EVI and LAI decline were observed for drought events during 2003, 2007, and 2012 years. The vegetation phenology analysis was correlated with associated time series of climatic variables in order to detect recorded anomalies. Temperature, rainfall and radiation were significantly correlated with almost all forest land-cover classes, while vegetation phenology was not correlated with climatic variables for the same period of analysis, suggesting a delay between climatic biophysical parameters variations and forest vegetation response. Under stress conditions, it is evident that environmental factors such as soil type, parent material, and topography are not correlated with NDVI/EVI dynamics.
A spatio-temporal analysis of the aerosol concentrations in two size fractions (PM10 and PM2.5) in relation with air quality (AQI) and meteorological parameters was done through synergy of in-situ monitoring data as well as MODIS Terra/Aqua time-series satellite data for Bucharest metropolitan area during 2012 year. The C005 (version 5.1) Level 2 and Level 3 Terra MODIS AOD550 time-series satellite data for period 01/01/2012- 31/12/2012 have been used. ORIGIN 8.0 and ENVI 5.0 software were used. All these methods are important and complementary. It was found that Particle Materials PM2.5 and PM10 aerosols exhibit their highest concentrations mostly in the central part of the town, due to road traffic as well as in the industrialized periurban areas. In addition to the local and regional anthropogenic PM sources, both the levels and composition of air PM depend on meteorological parameters (temperature, humidity, precipitation, winds etc.), and season of the year. The results revealed a significant month-to-month variability in all AOD550 values, underlying the influence of varying aerosol load function of season. The AOD550 values (Level 3) lie in a wide range, as low as 0.2 up to 0.5. The influence of aerosol particles on climate, and how their properties are perturbed by anthropogenic activity, is one of the key uncertainties in climate change assessments. These results contribute to a better understanding of urban decision makers through considering the specific characteristics of different urban sectors for air quality improvement.
This study investigated the influences of urban growth changes and extreme climate events on land surface temperature in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from Landsat TM/ETM/OLI and time series MODIS Terra/Aqua and NOAA AVHRR sensors have been used to assess urban land cover– temperature interactions over 2000 - 2017 period. Time series Thermal InfraRed (TIR) satellite remote sensing data in synergy with meteorological data (air temperature- Ta, precipitations, wind, solar radiation, etc.) have been applied mainly for analyzing land surface temperature (LST) patterns and its relationship with surface landscape characteristics, assessing urban heat island (UHI), and relating urban land cover temperatures (LSTs). Based on these parameters, the urban size dynamics, urban heat island effect (UHI) and the relationships of LST to other biophysical and meteorological parameters (surface albedo, precipitations, wind intensity and direction, air temperature) have been analyzed. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, LST and Ta possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at metropolitan scale respectively. The NDVI was significantly correlated with precipitation. The spatial average air temperatures in urban test areas rise with the expansion of the urban size.
Earthquake science has entered a new era with the development of space-based technologies to measure surface geophysical parameters and deformation at the boundaries of tectonic plates and large faults. Satellite time-series data, coupled with ground based observations where available, can enable scientists to survey pre-earthquake signals in the areas of strong tectonic activity. Cumulative stress energy in seismic active regions under operating tectonic force manifests various earthquakes’ precursors. Space-time anomalies of Earth’s emitted radiation (thermal infrared in spectral range measured from satellite months to weeks before the occurrence of earthquakes, radon in underground water and soil, etc.), and electromagnetic anomalies are considered as pre-seismic signals. This paper presents observations made using time series MODIS Terra/Aqua and NOAA-AVHRR satellite data for derived multi-parameters land surface temperature (LST), outgoing long-wave radiation (OLR), net surface latent heat flux (LHF), mean air temperature (AT), Relative Humidity (RH), and reanalysis data sets for some moderate or strong seismic events recorded in Vrancea region in Romania, which is one of the most active intracontinental seismic areas in Europe. Starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (oC) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock. These observations support seismic LSAIC (Lithosphere – Surfacesphere – Atmosphere -Ionosphere Coupling) Model.
Earthquakes are dynamic phenomena that can be predicted by some geophysical and geochemical anomalies occurring in lithosphere, surfacesphere, atmosphere and ionosphere during preparation phase. These seismic LSAIC (Lithospheric- Surfacespheric-Atmospheric-Ionospheric Coupling) perturbations are widely considered as earthquake presignals. The most important earthquake precursors which can be detected from space are: a)temperature changes (detected through air and land surface temperature, Aerosol Optical Depth (AOD) as well as anomalies recorded by outgoing long-wave radiation and latent heat flux from TIR (Thermal InfraRed) spectral bands of time-series satellites MODIS Terra/Aqua , NOAA AVHRR, ASTER, Landsat TM/ETM data; b) ground surface deformations detected through Synthetic Aperture Radar Interferometry (InSAR) radar satellite (Sentinel 1) and high quality in-situ GPS monitoring data as well as from time series satellite data in optical range (VIS and IR) from Landsat TM/ETM/OLI, MODIS Terra/Aqua, IKONOS, and Quickbird etc. for geologic lineaments changes location; c) electric and magnetic fields anomalies developed weeks to hours- before the main shock (ionospheric TEC-Total Electron Content, solar and geomagnetic indices which can be detectable from SWARM, GOCE satellites, and in-situ monitoring radon, gamma rays, etc. This paper aims to present analysis of seismic multi-presignals detected through changes of geophysical and geochemical parameters from time-series geospatial and field data for some moderate earthquakes recorded in Vrancea seismic region in Romania. As Vrancea zone in Carpathians has a significant regional tectonic activity in Romania and Europe, the joint analysis of satellite and in-situ geophysical information is revealing new insights in the field of hazard assessment.
Drivers of global climate change and the increased frequency of extreme climate events may affect urban and periurban forest ecosystems more rapidly than natural forest ecosystems. Multi stressors of urban forest ecosystems include alterations in forest soils and to the diversity and composition of forest ecosystem, as well as higher temperatures during heat waves periods and increasing carbon dioxide content due to high traffic issue. Global conservation targets and management practices of urban forest ecosystems in Romania requires adequate novel monitoring methodology for monitoring the dynamics changing status. Ground-based measurements are valuable tools with limited spatial footprints. Multispectral and multitemporal satellite remote sensing data allow detailed information on forest structure and can deliver ecologically relevant, long-term datasets suitable of vegetation phenology for analyzing changes in periurban and urban forest ecosystem areas, structure and function at temporal and spatial scales relevant to forest dynamics monitoring. The aim of this paper was to evaluate and characterize forest changes for selected test area Cernica –Branesti in Ilfov county located in the Eastern part of Bucharest metropolitan region, Romania, where the climate and anthropogenic stressors endanger natural and economical values of forest environment. Based on time-series Landsat 5 TM, 7 ETM+, 8 OLI/TIRS, MODIS Terra/Aqua and Sentinel 2A satellite data have been investigated urban forest land cover and forest biophysical parameters (LST, NDVI/EVI and LAI) changes over 2000-2016 period of time. Accuracy of image processing results (spectral classification) was confirmed through in-situ spectroradiometrical analysis of reflectance spectra with portable GER 2600 spectroradiometer.
Due to anthropogenic and climatic changes, Carpathian Mountains forests in Romania experience environmental degradation. As a result of global climate change, there is growing evidence that some of the most severe weather events could become more frequent in Romania over the next 50 to 100 years. In the case of Carpathian mountain forests, winter storms and heat waves are considered key climate risks, particularly in prealpine and alpine areas. Effects of climate extremes on forests can have both short-term and long-term implications for standing biomass, tree health and species composition. The preservation and enhancement of mountain forest vegetation cover in natural, semi-natural forestry ecosystems is an essential factor in sustaining environmental health and averting natural hazards. This paper aims to: (i) describe observed trends and scenarios for summer heat waves, windstorms and heavy precipitation, based on results from satellite time series NOAA AVHRR, MODIS Terra/Aqua and Landsat TM/ETM+/OLI NDVI and LAI data recorded during 2000-2016 period correlated with meteorological parameters, regional climate models, and other downscaling procedures, and (ii) discuss potential impacts of climate changes and extreme events on Carpathian mountain forest system in Romania. The response of forest land cover vegetation in Carpathian Mountains, Romania to climatic factors varies in different seasons of the years, the diverse vegetation feedbacks to climate changes being related to different vegetation characteristics and meteorological conditions. Based on integrated analysis of satellite and field data was concluded that forest ecosystem functions are responsible of the relationships between mountain specific vegetation and climate.
Time series analysis of GPS (Global Positioning Systems) and InSAR (Interferometric Synthetic Aperture Radar) data are important tools for Earth’s surface deformation assessment, which can result from a wide range of geological phenomena like as earthquakes, landslides or ground water level changes. The aim of this paper was to identify several types of earthquake precursors that might be observed from geospatial data in Vrancea seismogenic region in Romania. Continuous GPS Romanian network stations and few field campaigns data recorded between 2005-2012 years revealed a displacement of about 5 or 6 millimeters per year in horizontal direction relative motion, and a few millimeters per year in vertical direction. In order to assess possible deformations due to earthquakes and respectively for possible slow deformations, have been used also time series Sentinel 1 satellite data available for Vrancea zone during October 2014 till October 2016 to generate two types of interferograms (short-term and medium- term). During investigated period were not recorded medium or strong earthquakes, so interferograms over test area revealed small displacements on vertical direction (subsidence or uplifts) of 5-10 millimeters per year. Based on GPS continuous network data and satellite Sentinel 1 results, different possible tectonic scenarios were developed. The localization of horizontal and vertical motions, fault slip, and surface deformation of the continental blocks provides new information, in support of different geodynamic models for Vrancea tectonic active region in Romania and Europe.
This study investigated the influences of city land cover changes and extreme climate events on land surface temperature in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from IKONOS, Landsat TM/ETM+ and time series MODIS Terra/Aqua and NOAA AVHRR sensors have been used to assess urban land cover– temperature interactions over 2000 - 2016 period. Time series Thermal InfraRed (TIR) satellite remote sensing data in synergy with meteorological data (air temperatureAT, precipitations, wind, solar radiation, etc.) were applied mainly for analyzing land surface temperature (LST) pattern and its relationship with surface landscape characteristics, assessing urban heat island (UHI), and relating urban land cover temperatures (LST). The land surface temperature, a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, LST and AT possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at metropolitan scale respectively. The NDVI was significantly correlated with precipitation. The spatial average air temperatures in urban test areas rise with the expansion of the urban size.
During last decade, due to fast progress of thermal infrared (TIR) technology, all weather, high-resolution and highdynamic
range of new developed sensors, a large time-series data base is available for seismic anomalies monitoring. As
received satellite infrared information is influenced by many types of factors, the main problem for seismic anomalies
recognition is to extract useful information associated with tectonic activities and to eliminate the effects of non-tectonic
factors. Pre-earthquake spatio-temporal thermal anomalies are controlled by various factors like as earthquake moment
magnitude and its focal depth, geological setting, topography and land covers. In this paper, changes before and after the
Vrancea earthquakes in the atmospheric parameters have been investigated on the basis of time-series geospatial and
field data analysis. The detected changes show a complementary behavior in terms of the various atmospheric
parameters, further showing strong evidence of coupling between lithosphere-land surface-atmosphere associated with
the Vrancea’s earthquakes. Have been selected the atmospheric earthquake presignals detectable from space: surface
latent heat flux (SLHF), and air (AT) surface temperature anomalies, provided by time-series satellite NOAA AVHRR
and in-situ monitoring data. For some analyzed earthquakes, starting with ten days up to one week prior to a moderate or
strong earthquake a transient thermal infrared rise appeared in SLHF (tens of W/m2) and AT (2-10°) values higher than
the normal, function of the magnitude and focal depth, which disappeared after the main shock. The joint analysis of
geospatial, geophysical, and geological information is revealing new insights for Vrancea zone seismicity understanding
in Romania.
This study investigated the influences of urban growth and heat waves events on Urban Heat Island in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from Landsat TM/ETM+ and time series NOAA AVHRR and MODIS Terra/Aqua sensors have been used to assess urban land cover– temperature interactions over period between 2000 and 2016 years. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban growth. The land surface temperature (LST), a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Based on these parameters, the urban growth, urban heat island effect (UHI) and the relationships of Ts to other biophysical parameters (surface albedo, precipitations, wind intensity and direction) have been analyzed. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, LST possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. This analysis provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling.
The increase of urban atmospheric pollution due to particulate matters (PM) in different fraction sizes affects seriously not only human health and environment, but also city climate directly and indirectly. In the last decades, with the economic development and the increased emissions from industrial, traffic and domestic pollutants, the urban atmospheric pollution with remarkable high PM2.5 (particulate matters with aerodynamic diameter less than 2.5 μm) and PM10 (particulate matters with aerodynamic diameter less than 10 μm) concentration levels became serious in the metropolitan area of Bucharest in Romania. Both active as well as satellite remote sensing are key applications in global change science and urban climatology. The aerosol parameters can be measured directly in situ or derived from satellite remote sensing observations. All these methods are important and complementary. The current study presents a spatiotemporal analysis of the aerosol concentrations in relation with climate parameters in two size fractions (PM10 and PM2.5) in Bucharest metropolitan area. Daily average particle matters concentrations PM10 and PM2.5 for Bucharest metropolitan area have been provided by 8 monitoring stations belonging to air pollution network of Environmental Protection Agency. The C005 (version 5.1) Level 2 and Level 3 Terra and Aqua MODIS AOD550 time-series satellite data for period 01/01/2011- 31/12/2012 have been also used. Meteorological variables (air temperature, relative humidity, sea level atmospheric pressure) have been provided by in-situ measurements. Both in-situ monitoring data as well as MODIS Terra/Aqua time-series satellite data for 2011-2012 period provided useful tools for particle matter PM2.5 and PM10 monitoring.
This study investigated the influences of urban growth and heat waves events on Urban Heat Island in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from Landsat TM/ETM+ and time series MODIS Terra/Aqua sensors have been used to assess urban land cover– temperature interactions over period between 2000 and 2016 years. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban growth. The land surface temperature (Ts), a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Based on these parameters, the urban growth, urban heat island effect (UHI) and the relationships of Ts to other biophysical parameters (surface albedo, precipitations, wind intensity and direction) have been analyzed. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. This analysis provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling.
This paper presents observations based on in-situ and time series MODIS Terra/Aqua and NOAA-AVHRR satellite data on derived anomalies of multi geophysical parameters (land surface temperature -LST, outgoing long-wave radiation- OLR, and mean air temperature- AT for some seismic events recorded in Vrancea seismic region in Romania. Starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (°C) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock. A developed Lithosphere-Surfacesphere-Atmosphere-Ionosphere Coupling (LSAIC) model can explain most of these presignals as a synergy between different anomalies of geophysical/geochemical parameters. These anomalies prior to medium to strong earthquakes are attributed to the thermodynamic, degassing and ionization processes in the Earth- Atmosphere system and micro-fracturing in the rocks especially along area’s active faults. The main outcome of this paper is an unified concept for systematic validation of different types of earthquake precursors of which Land Surface Temperature (LST), outgoing Long wave Radiation (OLR), Air Temperature (AT), radon gas concentration, are the most reliable parameters within the chain of the processes described by a LSAIC model.
Climate change is considered to be the biggest environmental threat in the future in the South- Eastern part of Europe. In frame of predicted global warming, urban climate is an important issue in scientific research. Surface energy processes have an essential role in urban weather, climate and hydrosphere cycles, as well in urban heat redistribution. This paper investigated the influences of urban growth on thermal environment in relationship with other biophysical variables in Bucharest metropolitan area of Romania. Remote sensing data from Landsat TM/ETM+ and time series MODIS Terra/Aqua sensors have been used to assess urban land cover– climate interactions over period between 2000 and 2015 years. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban growth. The land surface temperature (Ts), a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Based on these parameters, the urban growth, and urban heat island effect (UHI) and the relationships of Ts to other biophysical parameters have been analyzed. The correlation analyses revealed that, at the pixel-scale, Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. This analysis provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling.
Space-time anomalies of Earth’s emitted radiation: thermal infrared in spectral range measured from satellite months to weeks before the occurrence of earthquakes, radon in underground water and soil, etc., and electromagnetic anomalies are considered as pre-seismic signals. Satellite remote sensing provides spatially continuous information of the tectonic landscape but also contribute to the understanding of specific fault and information about stress transfer between fault systems from depth and to the surface as well as on released energy by earthquakes and other modes of deformation. This paper presents observations made using time series MODIS Terra/Aqua, NOAA-AVHRR, Landsat satellite data for derived multi-parameters land surface temperature (LST), outgoing long-wave radiation (OLR), and mean air temperature (AT) for some seismic events recorded in Vrancea active geotectonic region in Romania. For some analyzed earthquakes, starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (oC) and the increased OLR values higher than the normal function of the magnitude and focal depth, which disappeared after the main shock. Synergy of multisenzor and multitemporal satellite data with in-situ and GPS data and spatial analysis of magnitude–frequency distributions of Vrancea earthquakes provides more information on Vrancea area seismicity. Earthquake hazard assessment for Vrancea region in Romania must have different degrees of complexity, which consists of derived geospatial and in-situ geophysical/geodetic parameters monitoring, analysis, predictive modeling, and forecast-oriented as well as decision-making procedures.
Understanding spatio-temporal changes of urban environments is essential for regional and local planning and environmental management. With the rapid changes of Bucharest city in Romania during past decades, green spaces have been fragmented and dispersed causing impairment and dysfunction of these urban elements. The main goal of this study is to address these tasks in synergy with in-situ data and new analytical methods. Spatio- temporal monitoring of urban vegetation land cover changes is important for policy decisions, regulatory actions and subsequent land use activities. This study explored the use of time-series MODIS Terra/Aqua Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), Land Surface Temperature (LST) and evapotranspiration (ET) data to provide vegetation change detection information for metropolitan area of Bucharest. Training and validation are based on a reference dataset collected from IKONOS high resolution remote sensing data. The mean detection accuracy for period 2002- 2014 was assessed to be of 87%, with a reasonable balance between change commission errors (20.24%), change omission errors (25.65%), and Kappa coefficient of 0.72. Annual change detection rates across the urban/periurban areas over the study period (2002–2014) were estimated at 0.79% per annum in the range of 0.46% (2002) to 0.77% (2014).Vegetation dynamics in urban areas at seasonal and longer timescales reflect large-scale interactions between the terrestrial biosphere and the climate system. Extracted green space areas were further analyzed quantitatively in relation with air quality data and extreme climate events. The results have been analyzed in terms of environmental impacts and future climate trends.
With the development of space-based technologies to measure surface geophysical parameters and deformation at the boundaries of tectonic plates and large faults, earthquake science has entered a new era. Using time series satellite data for earthquake prediction, it is possible to pursue the behaviors of earthquake precursors in the future and to announce early warnings when the differences between the predicted value and the observed value exceed the pre-define threshold value. Starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (oC) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock. Also are recorded associated geomagnetic and ionospheric distrurbances. Vrancea tectonic active zone in Romania is characterized by a high seismic hazard in European- Mediterranean region, being responsible of strong or moderate intermediate depth and normal earthquakes generation on a confined epicentral area. Based on recorded geophysical parameters anomalies was developed an integrated geospatial system for earthquake precursors assessment in Vrancea active seismic zone. This system integrates derived from time series MODIS Terra/Aqua, NOAA-AVHRR, ASTER, Landsat TM/ETM satellite data multi geophysical parameters (land surface temperature -LST, outgoing long-wave radiation- OLR, and mean air temperature- AT as well as geomagnetic and ionospheric data in synergy with in-situ data for surveillance and forecasting of seismic events.
With the increasing industrialization and urbanization, especially in the metropolis regions, aerosol pollution has highly negative effects on environment. Urbanization is responsible of three major changes that may have impact on the urban atmosphere: replacement of the natural surfaces with buildings and impermeable pavements, heat of anthropogenic origin and air pollution. The importance of aerosols for radiative and atmospheric chemical processes is widely recognized. They can scatter and/or absorb solar radiation leading to changes of the radiation budget. Also, the so-called indirect effect of aerosols describes the cloud-aerosol interactions, which can modify the chemical and physical processes in the atmosphere. Their high spatial variability and short lifetime make spaceborne sensors especially well suited for their observation. Remote sensing is a key application in global-change science and urban climatology. Since the launch of the MODerate resolution Imaging Spectroradiometer (MODIS) there is detailed global aerosol information available, both over land and oceans The aerosol parameters can be measured directly in situ or derived from satellite remote sensing observations. All these methods are important and complementary. The objective of this work was to document the seasonal and inter-annual patterns of the aerosol pollution particulate matter in two size fractions (PM10 and PM2.5) loading and air quality index (AQI) over Bucharest metropolitan area in Romania based on in-situ and MODIS (Terra–Moderate Resolution Imaging Spectoradiometer) satellite time series data over 2010-2012 period. Accurate information of urban air pollution is required for environmental and health policy, but also to act as a basis for designing and stratifying future monitoring networks.
Results obtained by FEM analysis of a smart mechanical part manufactured of reinforced composite materials with embedded long period grating fiber sensors (LPGFS) used for operation monitoring are presented. Fiber smart reinforced composite materials because of their fundamental importance across a broad range of industrial applications, as aerospace industry. The main purpose of the performed numerical analysis consists in final improved design of composite mechanical components providing a feedback useful for further automation of the whole system. The performed numerical analysis is pointing to a correlation of composite material internal mechanical loads applied to LPGFS with the NIR absorption bands peak wavelength shifts. One main idea of the performed numerical analysis relies on the observed fact that a LPGFS embedded inside a composite material undergoes mechanical loads created by the micro scale roughness of the composite fiber network. The effect of this mechanical load consists in bending of the LPGFS. The shifting towards IR and broadening of absorption bands appeared in the LPGFS transmission spectra is modeled according to this observation using the coupled mode approach.
The paper presents the results obtained in simulation of a Superstructure Fiber Bragg Grating (SFBG) torsion sensor. The SFBG sensor simulation points to an improved smart composite or metallic parts design to be operated under torsion loads in various applications. SFBG sensor simulation consists of correlating the fiber deformation under applied mechanical loads with the modified FBG characteristic reflection spectrum considering the polarization mode variations. The analyzed SFBG is developed by the selective deposition of on-fiber periodic metal thin films on regular FBGs. The torsion mechanical loads induced shifts in the characteristic reflection spectrum of Bragg wavelength and side bands are analyzed. For obtaining information about an optimal structure of SFBG sensor, simulation is performed for four commercially available photosensitive single mode silica optical fibers having different geometric and optical characteristics, mainly core and clad refractive index values. It is considered that, by using an UV writing technique, Brag gratings are induced into the simulated SFBG. Simulations are performed considering different geometric characteristics of the shaft used as mechanical mount of SFBG. The simulation results are in fairly good agreement with the experimental ones reported in literature.
In this paper we present several numerical simulations of the surface plasmon resonance for Kretschmann type configuration in a metal-chalcogenide waveguide. We assume that the chalcogenide (GaLaS) waveguide layer have finite thickness, whereas the gold film layer and the air cover layer are semi-infinite layers (from an optical point of view). We determined the thickness of the chalcogenide film for which plasmonic resonant coupling of the incident radiation to the waveguide occurs. We calculated the propagation constant for the TE- and TM- modes (both for visible and IR domain), the attenuation coefficient and the electromagnetic field distribution within the waveguide. The obtained results provide the conditions for design an optical memory device 2D based on light-light interaction in plasmonic configuration.
Earthquake science has entered a new era with the development of space-based technologies to measure surface geophysical parameters and deformation at the boundaries of tectonic plates and large faults. Satellite time-series data, coupled with ground based observations where available, can enable scientists to survey pre-earthquake signals in the areas of strong tectonic activity. Cumulative stress energy in seismic active regions under operating tectonic force manifests various earthquakes’ precursors. Space-time anomalies of Earth’s emitted radiation (thermal infrared in spectral range measured from satellite months to weeks before the occurrence of earthquakes, radon in underground water and soil, etc.), and electromagnetic anomalies are considered as pre-seismic signals. Vrancea tectonic active zone in Romania is characterized by a high seismic hazard in European- Mediterranean region, being responsible of intermediate depth and normal earthquakes generation on a confined epicentral area.Anomaly detection is extremely important for forecasting the date, location and magnitude of an impending earthquake. This paper presents observations made using in-situ data and time series MODIS and NOAA-AVHRR satellite data for derived multi geophysical parameters (land surface temperature -LST, outgoing long-wave radiation- OLR, net surface latent heat flux (LHF) and mean air temperature- AT for some seismic events recorded in Vrancea region in Romania, which is one of the most active intracontinental seismic areas in Europe. Starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (°C) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock.
Cities are exposed more and more to climate change from greenhouse gas induced radiative forcing, and localized effects from urbanization such as the urban heat island. Urban land covers as the biophysical state of the earth’s surface and immediate subsurface are sources and sinks for most of the material and energy movements and interactions between the geosphere and biosphere. Climate change is considered to be the biggest environmental threat in the future in the South- Eastern part of Europe. The aim of this paper is to investigate the influences of urban growth on urban thermal environment as well as the relationships of thermal characteristics to other biophysical parameters in Bucharest metropolitan area of Romania based on time series MODIS Terra/Aqua and IKONOS data acquired during 2000-2014 periods. Land Surface Temperature (LST) is a key variable for studying urban land surface processes and surface atmosphere interactions, being a crucial component in the study of the surface energy and water budgets. Urbanization created an evolved inverse relationship between impervious and vegetation coverage, and brought about new LST patterns because of LST’s correlations with both impervious and vegetation coverage. City thermal environment risk management strategies for mitigating and adapting to climate change must propose efficient plans to reduce greenhouse gas (GHG) emissions and cool the city through changes in the built environment, land use, and transportation.
This study aimed to evaluate the concept of using high-resolution optical coherence tomography (OCT) imaging to rapidly assess surgical specimens and determine if cancer positive margins were left behind in the surgical bed. A mouse model of breast cancer was used in this study. Surgical specimens from 30 animals were investigated with OCT and automated interpretation of the OCT images was performed and tested against histopathology findings. Specimens from 10 animals were used to build a training set of OCT images, while the remaining 20 specimens were used for a validation set of images. The validation study showed that automated interpretation of OCT images can differentiate tissue types and detect cancer positive margins with at least 81% sensitivity and 89% specificity. The findings of this pilot study suggest that OCT imaging of surgical specimens and automated interpretation of OCT data may enable in the future real-time feedback to the surgeon about margin status in patients with breast cancer, and potentially with other types of cancers. Currently, such feedback is not provided and if positive margins are left behind, patients have to undergo another surgical procedure. Therefore, this approach can have a potentially high impact on breast surgery outcome.
Due to anthropogenic and natural factors, forest land covers changes result is the land surfaces albedo changes. The main aim of this paper is to investigate the albedo patterns dynamics due to the impact of atmospheric pollution and climate variations on a periurban forest Cernica-Branesti placed to the North-Eastern part of Bucharest city, Romania based on satellite remote sensing MODIS Terra/Aqua (Moderate Imaging Spectroradiometer) data over 2003–2012 time period. This study is based on MODIS derived biogeophysical parameters land surface BRDF/albedo products and in-situ monitoring ground data (as air temperature, aerosols distribution, relative humidity, etc.). For forest land cover changes over the same investigated period have been used also Landsat TM/ETM and IKONOS imagery. Have been analyzed also other biogeophysical effects of forest land cover change in addition to surface albedo, particularly changes in the surface moisture budget leading to shifts in the ratio of latent and sensible heat fluxes and changes in rate of land surface temperature and precipitation. Due to deforestation albedo change appears to be the most significant biogeophysical effect in temperate forests. Satellite data and climate station observations show that surface albedo changes of a forested zone placed close to a large urban area highly respond to atmospheric pollution influence and climate variations. As the physical climate system is very sensitive to surface albedo, forest ecosystems could significantly feedback to the projected climate change modeling scenarios through
albedo changes.
Urban vegetation land cover change is a direct measure of quantitative increase or decrease in sources of urban pollution
and the dimension of extreme climate events and changes that determine environment quality. Spatio- temporal
monitoring of urban vegetation land cover changes is a very important task for establishing the links between policy
decisions, regulatory actions and subsequent land use activities. Former studies incorporating two-date change detection
using Landsat TM/ETM data had limited performance for urban biophysically complex systems applications. In this
paper, we describe recent results using data from NASA’s Moderate Resolution Imaging Spectroradiometer and
NOAA/AVHRR satellite to study urban vegetation land cover dynamics. This study explored the use of time-series
MODIS Terra/Aqua Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI), data to provide
change detection information for metropolitan area of Bucharest in Romania. Training and validation are based on a
reference dataset collected from IKONOS high resolution remote sensing data. The mean detection accuracy for period
2002- 2012 was assessed to be of 89%, with a reasonable balance between change commission errors (21.7%), change
omission errors (28.5%), and Kappa coefficient of 0.69. Annual change detection rates across the urban/periurban areas over the study period (2002–2012) were estimated at 0.78% per annum in the range of 0.45% (2002) to 0.75%
(2012).Vegetation dynamics in urban areas at seasonal and longer timescales reflect large-scale interactions between the terrestrial biosphere and the climate system.
In frame of global warming, the field of urbanization and urban thermal environment are important issues among
scientists all over the world. This paper investigated the influences of urbanization on urban thermal environment as well
as the relationships of thermal characteristics to other biophysical variables in Bucharest metropolitan area of Romania
based on satellite remote sensing imagery Landsat TM/ETM+, time series MODIS Terra/Aqua data and IKONOS
acquired during 1990 - 2012 period. Vegetation abundances and percent impervious surfaces were derived by means of
linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to
accurately examine the urban growth. The land surface temperature (Ts), a key parameter for urban thermal
characteristics analysis, was also retrieved from thermal infrared band of Landsat TM/ETM+, from MODIS Terra/Aqua
datasets. Based on these parameters, the urban growth, urban heat island effect (UHI) and the relationships of Ts to other
biophysical parameters have been analyzed. Results indicated that the metropolitan area ratio of impervious surface in
Bucharest increased significantly during two decades investigated period, the intensity of urban heat island and heat
wave events being most significant. The correlation analyses revealed that, at the pixel-scale, Ts possessed a strong
positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. This analysis provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling.
During last years urban vegetation with significant health, biological and economical values had experienced dramatic changes due to urbanization and human activities in the metropolitan area of Bucharest in Romania. We investigated the utility of remote sensing approaches of multiple endmember spectral mixture analysis (MESMA) applied to IKONOS and Landsat TM/ETM satellite data for estimating fractional cover of urban/periurban forest, parks, agricultural vegetation areas. Because of the spectral heterogeneity of same physical features of urban vegetation increases with the increase of image resolution, the traditional spectral information-based statistical method may not be useful to classify land cover dynamics from high resolution imageries like IKONOS. So we used hierarchy tree classification method in classification and MESMA for vegetation land cover dynamics assessment based on available IKONOS high-resolution imagery of Bucharest town. This study employs thirty two endmembers and six hundred and sixty spectral models to identify all Earth’s features (vegetation, water, soil, impervious) and shade in the Bucharest area. The mean RMS error for the selected vegetation land cover classes range from 0.0027 to 0.018. The Pearson correlation between the fraction outputs from MESMA and reference data from all IKONOS images 1m panchromatic resolution data for urban/periurban vegetation were ranging in the domain 0.7048 - 0.8287. The framework in this study can be applied to other urban vegetation areas in Romania.
To preserve urban vegetation land cover quality and mitigate its degradation is an important task for urban planning and
environmental management of Bucharest metropolitan area in Romania. Since vegetation land cover dynamics directly
affect the urban landscape characteristics and air quality, remote sensing represents an effective tool for vegetation land
cover quality assessment at regional scale. In particular, the use of satellite-based vegetation indices, like the NDVI
(Normalized Difference Vegetation Index), can provide important information when evaluating Urban Vegetation Cover
Quality (UVCQ) patterns in urban areas, which represents one of the most sensitive landscape components to urban
environmental degradation. This paper proposes an approach for the regional-scale assessment of UVCQ by means of an
NDVI-based (functional) indicator using freely available time series MODIS Terra/Aqua (Moderate Resolution Imaging
Spectroradiometer) satellite data. As a case study, Bucharest metropolitan area landscape experiencing climate and
anthropogenic changes, increasing human pressure and high vulnerability to degradation was chosen. As UVCQ
indicator, the NDVI-based vegetation cover classification was produced by means of unsupervised multivariate statistical
techniques and compared with spatio-temporal changes during 2002-2012 period, statistical indicators, and field data
related to land cover management observed in the study area. Results demonstrate that the obtained remotely sensed
vegetation land cover characterization can be effectively considered as a proxy of the UVCQ status of the examined area.
Due to the large availability over time and low cost of satellite images, the proposed approach can be applied to wider
urban/periurban regions, to monitor vegetation quality and indirectly control vegetation land degradation.
Satellite time-series data, coupled with ground based observations where available, can enable scientists to survey pre-earthquake signals in the areas of strong tectonic activity. Cumulative stress energy in seismic active regions under operating tectonic force manifests various earthquakes’ precursors. Space-time anomalies of Earth’s emitted radiation (radon in underground water and soil, thermal infrared in spectral range measured from satellite months to weeks before the occurrence of earthquakes etc.), and electromagnetic anomalies are considered as pre-seismic signals. This energy transformation may result in enhanced transient thermal infrared (TIR) emission, which can be detected through satellites equipped with thermal sensors like AVHRR (NOAA), MODIS (Terra/Aqua). This paper presents observations made using time series NOAA-AVHRR and MODIS satellite data–derived land surface temperature (LST) and outgoing longwave radiation (OLR) values in case of 27th 2004 earthquake recorded in seismic Vrancea region, Romania, using anomalous TIR signals as reflected in LST rise and high OLR values which followed similar growth pattern spatially and temporally. In all analyzed cases, starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (°C) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock. As Vrancea area has a significant regional tectonic activity in Romania and Europe, the joint analysis of geospatial and in-situ geophysical information is revealing new insights in the field of hazard assessment.
Climate variability and change are risk factors for climate sensitive activities such as forestry. Managing these risks requires “climate knowledge”, i.e. a sound understanding of causes and consequences of climate variability and knowledge of potential management options that are suitable in light of the climatic risks posed. Thresholding based on biophysical variables derived from time series satellite data is a new approach to classifying forest land cover via remote sensing through use of Normalized Difference Vegetation Index –NDVI and Enhanced vegetation Index- EVI. This paper aims to assess spatio-temporal forest changes through applied time-series Landsat TM, ETM, MODIS Terra/Aqua and IKONOS satellite remote sensing data of Cernica forest area near Bucharest, Romania, during 1990-2011 period. Additional forest biophysical parameter Land Surface Temperature/Emissivity - LST was considered in this paper. This information is complemented by in-situ monitoring data (field measurements, data collection) together with modeling tools (theoretical developments, mathematical and bio-geophysical parameterization, statistics of the main urban structures in their interdependency) and spatial analysis methods.
Various aspects of distributed feedback fiber laser sensors, their interaction with environment and their possible applications are investigated by numerically solving coupled-mode equations system describing the laser field propagation. The developed numerical analysis has the aim to better understand the DFB-FL itself and its interaction with environment in order to be operated as a sensor. The main idea consists in finding out how various environment parameters modify the coefficients of coupled-mode equations describing the laser field propagation through the DFBFL structure.
Numerical simulation results obtained in investigating the generation of laser pulses with 1.55 μm wavelength generated by an Er3+, Er3+-Yb3+ or Cr3+-Yb3+-Er3+ laser or fiber laser oscillator operated in passive optical Q-switching regime are presented. Three types of passive optical Q-switch cell are investigated: the usual one based on Co2+ or UO2 embedded in different hosts; the second consisting of Co2+ nano-crystals. The spectroscopic characteristics of these Q-switch cells are analyzed and correlated with criteria obtained with a numerical simulation procedure based on solving a rate equation system.
Spectral patterns of different forest land cover can identify certain pollution compounds, and water stress conditions
based on the interaction of photons with the molecular structure of the forest target structure. Based on such methods, the objective of this research was to evaluate and characterize selected forest test area Baneasa- Tunari located in the Northern part of Bucharest metropolitan region, Romania, where the climate and anthropogenic stressors endanger natural and economical values of environment. Based on time-series Landsat TM, ETM, MODIS Terra/Aqua and IKONOS satellite data have been investigated urban forest land cover and forest biophysical parameters (Normalized Difference Vegetation Index- NDVI and Leaf Area Index- LAI) changes over 1990- 2011 period of time. Accuracy of image processing results (spectral classification) was confirmed through in-situ spectroradiometrical analysis of reflectance spectra with portable GER 2600 spectroradiometer.
Numerical simulation results obtained in investigating laser paint removal from different metal substrates, mainly aluminum and aluminum alloys, are presented. The main purpose of the developed simulation model is to define the laser installation specifications required for an operation that does not affect the substrate on which the paint is deposited. This is an important laser application in aeronautical industry. The developed simulation model considers transverse laser beam intensity distribution and, consequently, the temperature distribution in the processed mechanical component.
Preliminary results obtained in investigating a plane electromagnetic wave incident on a metal nanowire grating formed on a dielectric substrate, using FEM, are presented. The numerically simulated model is developed considering Cu, Au, Ag or other metal nanowire having a diameter of 40 nm - 800 nm, formed on dielectric substrates with a refractive index between 1.4 and 2.4. The transmission and reflection coefficients for refraction, specular reflection and first order diffraction are computed. The cases of dielectric substrate with metallic layers of different thicknesses deposited on the opposite side are also investigated.
This paper presents the results obtained in analyzing a quasi-cw flash-lamp pumped high power Nd:YAG slab laser
oscillator/two stages amplifier operated in passive optical Q-switching regime using LiF:F2- crystals with an improved design. A numerical simulation method based on laser rate equation is developed for theoretical analysis of a passively Q-switched Nd:YAG slab laser system. A comparison of simulation results with experimental data is also presented to certify the viability of the developed theoretical analysis method. Laser pulses output energy of 330 mJ at a FWHM time duration of 50-75 ns and at a repetition frequency of 10 – 25 kHz (pps) are reported and numerical simulation of these experimental results are presented pointing to the output parameters stability.
Metamaterials are artificially designed media that show averaged properties not yet encountered in nature. Among such
properties, the possibility of obtaining optical magnetism and negative refraction are the ones mainly exploited but
epsilon-near-zero and sub-unitary refraction index are also parameters that can be obtained. Such behaviour enables
unprecedented applications. Within this work, we will present various aspects of metamaterials research field that we deal with at our department. From the modelling part, we will present tour approach for determining the field enhancement in slits that have
dimensions in the 104 times smaller than the incident wavelength. This huge difference makes it almost impossible for
commercial software to handle thus analytical approached have to be employed. From the fabrication point of view, various 2D and 3D high resolution patterning techniques are used. The talk will describe the ones available within our group. We will present the electron-beam lithography approach for fabricating nano-antennae to be used in coupling of plasmonics waveguides to/from free space. Also, a 3D technique based on twophoton-polymerisation and isotropic metal deposition to fabricate metal-covered 3D photonic crystals will be discussed. From the measuring side we will present two THz based setups for obtaining material’s characteristics, both in the low as well as in the high THz range, thus having the possibility of describing a material from 0.1 to 10THz.
Rock microfracturing in the Earth's crust preceding a seismic rupture may cause local surface deformation fields, rock
dislocations, charged particle generation and motion, electrical conductivity changes, gas emission, fluid diffusion,
electrokinetic, piezomagnetic and piezoelectric effects. Space-time anomalies of Earth’s emitted radiation (radon in
underground water and soil , thermal infrared in spectral range measured from satellite months to weeks before the
occurrence of earthquakes etc.), ionospheric and electromagnetic anomalies are considered as pre-seismic signals.
Satellite remote sensing data provides a systematic, synoptic framework for advancing scientific knowledge of the Earth complex system of geophysical phenomena which often lead to seismic hazards. The GPS data provides exciting
prospects in seismology including detecting, imaging and analyzing signals in regions of seismo-active areas. This paper aims at investigating thermal seismic precursors for some major earthquakes in Romania in Vrancea area, occurred in 1977, 1986, 1990 and 2004, based on time series satellite data provided by NOAA and MODIS. Quantitative analysis of land surface temperature (LST) and ongoing long wave radiation (OLR) data extracted from satellite and in-situ monitoring available data recorded before and during the occurrence of earthquake events shows the consistent
increasing in the air and land surface in the epicentral locations several days before earthquake, and at different distances of hypocenters function of registered earthquake moment magnitude.
The main environmental issues affecting the broad acceptability of NPP (Nuclear Power Plant) are the emission of
radioactive materials, the generation of radioactive and heat waste, and the potential for nuclear accidents. Satellite
remote sensing is an important tool for spatio-temporal analysis and surveillance of environment, thermal heat waste of waters being a major concern in many coastal ecosystems involving nuclear power plants, as sharp changes in water
temperature can significantly affect the distribution and physiology of aquatic biota and contribute to global warming. The thermal plume signature in the NPP hydrological system in TIR (Thermal Infrared) spectral bands of Landsat TM and ETM TIR band 6, ASTER, and MODIS TIR bands time series satellite have been used for WST (Water Surface Temperature) detection, mapping and monitoring. As a test case the methodology was applied for NPP Cernavoda, Romania during period of 1990-2011 years. Thermal discharge from two nuclear reactors cooling is dissipated as waste heat in Danube-Black -Sea Channel and Danube River. If during the winter thermal plume is localized to an area of a few km of NPP, the temperature difference between the plume and non-plume areas being about 1.5 oC, during summer and fall, is a larger thermal plume up to 5- 6 km far along Danube Black Sea Channel, the temperature change being of about 1.0 oC.
The preliminary numerical simulation results obtained in the analysis of a landmine detection system based on laser
excitation of acoustic - seismic waves in the soil and observing its surface vibration above the embedded landmine are
presented. The presented numerical simulations comprise three main parts: 1) Laser oscillator and laser beam
propagation and absorption in soil; a laser oscillator operated in Q-switched regime is considered; different laser
wavelengths are investigated. 2) Acoustic - seismic wave generation by absorption in soil of laser pulse energy; 3)
Evaluation of acoustic - seismic wave generation by the buried in soil landmine; 4) Comparison of Distributed Feed-
Back Fiber Laser (DFB-FL) and Laser Doppler Vibrometer (LDV) detector used for soil vibrations evaluation. The
above mentioned numerical simulation is dedicated for evaluation of an integrated portable detection system.
As climatic variability and anthropogenic stressors are growing up continuously, must be defined the proper criteria for
forest vegetation assessment. In order to characterize current and future state of forest vegetation satellite imagery is a
very useful tool. Vegetation can be distinguished using remote sensing data from most other (mainly inorganic) materials
by virtue of its notable absorption in the red and blue segments of the visible spectrum, its higher green reflectance and,
especially, its very strong reflectance in the near-IR. Vegetation reflectance has variations with sun zenith angle, view
zenith angle, and terrain slope angle. To provide corrections of these effects, for visible and near-infrared light, was used
a developed a simple physical model of vegetation reflectance, by assuming homogeneous and closed vegetation canopy
with randomly oriented leaves. A simple physical model of forest vegetation reflectance was applied and validated for
Cernica forested area, near Bucharest town through two ASTER satellite data , acquired within minutes from one
another ,a nadir and off-nadir for band 3 lying in the near infra red, most radiance differences between the two scenes can
be attributed to the BRDF effect. Other satellite data MODIS, Landsat TM and ETM as well as, IKONOS have been
used for different NDVI and classification analysis.
Due to significant anthropogenic changes that have occurred in the last several decades in Bucharest city's landscape,
urbanization has become an important factor affecting urban surface parameters, hence in the surface-atmosphere
interaction processes, with a great potential to alter the local climate. Land use and land cover (LULC) influence a
variety of processes important in characterizing urban /periurban biophysical parameters' quality, including aerosol
deposition rates, biogenic emissions, albedo, surface temperatures, climatic parameters and other.
Analysis of surface biophysical parameters changes in urban/periurban areas of Bucharest town based on multi-spectral
and multi-temporal satellite imagery (Landsat TM, ETM and IKONOS) for 1989 - 2009 period provides the most
reliable technique of environmental monitoring regarding the net radiation and heat fluxes associated with urbanization
at the regional scale. Investigation of radiation properties, energy balance and heat fluxes is based on information derived
from various satellite sensors and in-situ monitoring data, linked to numerical models and quantitative biophysical
information extracted from spatially distributed NDVI-data and net radiation. This study attempts to provide
environmental awareness to urban planners suggesting that future changes in urban land cover could substantially affect
climate by altering biophysical land-atmosphere interactions.
Urban areas are currently among the most rapidly changing types of land cover on the planet. Remote sensing imagery
can provide a timely and synoptic view of urban land cover, as well as a means to monitor change in urbanizing
landscapes and to compare urban environments globally. To understand the ecology of urban systems, it is necessary to
quantify the spatial and temporal patterns of urbanization, which often requires dynamic modeling and spatial analysis.
Based on Spectral Mixture Analysis, this paper aims to provide a spatio-temporal analysis of urban structure for
Bucharest urban area based on multi-spectral and multi-temporal satellite imagery (LANDSAT TM, ETM; MODIS,
IKONOS) over 1989 - 2007 period. Accurate maps of urban tree and other surface cover types can provide critical
information to better understand urban ecosystems and help improve environmental quality and human health in urban
areas.
Environmental monitoring is essential information routinely required by the mining industry and regulators to
demonstrate that the environment is not adversely impacted by exploration and mining. New mining technologies can
not only exploit low-grade ores but also produce high volumes of tailings as mining wastes. Satellite remote sensing
imagery provided by Landsat TM and ETM sensors is an important investigation tool of mining waste cover screening,
mapping and monitoring at local and regional scales of areas containing multiple sources of mining-related heavy metals.
By this, satellite remote sensing data can help to rapidly assess the dimension of mining waste risk and therefore better
manage such a geohazard as well as for remediation programs.
Based on Landsat TM, ETM satellite data over 1989-2007 period, was possible to be achieved a discrimination between
weathered materials and other prone to acidification as well as to perform a spatio temporal landcover change detection
analysis in some mining waste areas in Maramures County, Romania. Accuracy of image processing results
(mineralogical classification) was confirmed through ground sampling and analysis of reflectance spectra with portable
GER 2600 spectroradiometer.
Light transport is currently used clinically both as a therapeutic tool and as a diagnostic tool. A concern in all these cases
is the difficulty of knowing which regions of the tissues are sufficiently illuminated for therapeutic results, or from which
regions the collected fluorescence was emitted. Development of optical models that explain the observed scattering
properties of soft biological tissues is of considerable interest. Such modeling can give how the scattering properties are
influenced by the numbers, sizes and arrangements of the tissue structure. In this article we give a brief overview of the
laser light transport in tissue and also discuss some representative applications of tissue optics for biomedical
applications.
Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by the optical properties
(effective scattering and absorption coefficient). A special Er:YAG device used for blood sampling without any pain is
presented. Our device emitting on 2940 nm has a special function. It can give four energy levels for four types of skin.
At 3000 nm there is an absorption peak in water, and the absorption in tissue is intense and the vaporization is immediate
and superficial without surrounding damages. Additionally, the very short duration of the pulse (a few hundred
microseconds) avoids the phenomenon of thermal diffusion.
To solve some microsurgical procedures in the anterior and posterior chambers using the photo disruptive effect, a
special Nd:YAG nanosecond laser device is presented. The Nd:YAG laser is q-switched (Cr4+:YAG). The laser beam is
expanded. After expansion, the laser beam is passed through a circular variable filter which is rotated by a processor,
allowing energy to be set at any value in the range of 0.5-10 mJ. Two infrared LED-phototransistor pairs are used to
position the filter. The laser beam is focused by the objective at 150 microns behind the object plane to avoid the damage
of the Intraocular Lens.
Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by optical properties (effective
scattering and absorption coefficient). In 2900 nm range, the effective scattering coefficient is much smaller than the
absorption coefficient. An Er:YAG skin puncher is presented. Thermal action of a laser beam can be described as one of
three types: hyperthermia, coagulation and volatilization, depending on the degree and the duration of tissue heating. We
are interested in the volatilization process that means a loss of material. The various constituents of the tissue disappear
in smoke at above 1000C in a relatively short time of around one tenth of a second. At the edges of the volatilization zone
there is a region of coagulation necrosis. In presented case of an Er:YAG laser operating in a free generation mode, the
mechanical effects can result from explosive vaporization. When the exposure time of the laser is lower than the
characteristic time of the thermal diffusion in the tissue, it produces a thermal containment with an accumulation of heat
without diffusion and an explosive vaporization of the target. The Er:YAG laser device has the pulse length of about 160
microseconds and four emitted energy levels. This device is used to punch the skin for blood sampling for different kinds
of analysis. The front panel of the device has four keys to select the desired energy according to the skin type.
The study of dynamics of spatial solitons in nonlinear and unidimesional fotonic crystals, with a periodical and nonlinear
fotonic network which is generated by Dirac function is presented. Are analysed comparisons and differences which
appear in development of periodical models describes by nonlinear Schrödinger equation. Also, is developed theory of
couple models for periodical modulation of refractive index.
Fudamental theory of spatial solitons are based to obtain discrete nonlinear Schrödinger equation with analyze of
stationary solutions on discrete models.
The paper presents preliminary laboratory results in an investigation by laser induce fluorescence of the
environmental effects on the seawater. The aim of the paper was to analyze the fluorescence of the polluted water in the
south area of the Romanian Black Sea coast. The characteristics of the spectral fluorescence of water (intensity, shape,
bands) were analysed in connection with the extraction area and pollutants type. The fluorescence spectra are compared
with those of natural seawater samples measured at different laser excitation wavelengths (266 nm, 355 nm and 532 nm).
Fluorescence spectra of DOM (Dissolved Organic Matter), oil products (OP) and phytoplankton were characterized in
correlation with the band of the water Raman scattering and by their specific fluorescence decay. Seawater physicochemical
parameters and chlorophyll concentration were taking into account in seawater pollution analysis.
The Nd:YAG solid state laser can be used in ophthalmologic microsurgery because of its specific wavelength of 1064 nm, which has the property to penetrate the transparent medium of the eye. We design a specific ophthalmic system, containing a Q-switch Nd:YAG laser, an optical stereomicroscope and an aiming system. This laser-stereomicroscope system is used for eye examination and for microsurgical proceedings like posterior capsulotomy and pupilar membranectomy. We had to design an optical scheme of the laser to settle the radiation route. In order to cover the medical domain of the energies, we calibrate eleven attenuation filters using ratiometric method. For a correct position of the place where the laser pulse strikes, we used an original system consisting of two red laser diodes mounted on each side of the binocular One of the advantages of this laser system is taht the output energies can be varied widely (0.8-15 mJ), making a great numbers of applications in clinical ophthalmology possible.
An ophthalmic surgical instrument is presented. It contains a specific Q-switch YAG:Nd laser, an optical stereomicroscope, two red output laser diodes and a digital system for optical processing of the microscope images. As Q-switch, a Cr4+:YAG crystal is used. It works in monopulse or double pulse regime. Four red spots mark the optical object plane. The laser beam is sent in the central part, between four spots and is focused at 150 microns behind the optical plane to reduce the risk of pitting the lens when performing posterior capsulotomies. In order to obtain eleven different energy levels in the (2÷10)mJ domain, eleven attenuators are used. The laser ophthalmic system must fulfill many precautions. The energy level, the pulse length and the used attenuators must have such values to eliminate every undesired effect in the medical applications. This instrument has an important application in posterior capsulotomies and posterior membranectomies.
This paper presents a comparative study of the laser cleaning regimes applied to colored substrates with various chromatic characteristics, including colored paper and printed paper with different dpi (dots per inch) values. Tests are done under microscope with high precision techniques, using controlled Nd:YAG laser. The wavelength preponderantly used in the experiments is the Nd:YAG fundamental regime (1064 nm). Parallel experiments at 532 nm have been developed on difficult cases, or when the results were not satisfactory with 1064 nm. The main part of the work presents some results on stamp cleaning. Experimental results indicate that cleaning efficiency is correlated with the color of substrate, age of the ink on the stamp, color quality and paper quality.
Work is oriented towards opto-mechanical constructive solutions with high precision for complex microscope equipment with laser for artwork restoration. An important part of the restoration protocols applied in different area of art restoration/conservation requests microscopic investigation and double operation decision - automatic and manual operation. Working distance control and its adjustment represents the main difficulty for automatic laser cleaning process. On the other hand, IR or UV laser spot have to be marked by a visible beam and to support user decision increasing the equipment accuracy. Paper presents the optical arrangement of a laser microscope for artwork, investigation and cleaning with an optical system of aiming and metrological principle of working distance control.
Complex up-graded equipment for visual analysis, measurement, positioning and intervention in microscopic field is described below. This system is not extremely automated because it have not obstructs the user's facilities and his possibility to operate immediately in the studied process. The high accurate system for positioning speculates the superior precision of the metrological criterions based on methods with symmetric framing. The present paper indicates just the final solution and mentioned some interesting remarks about the disadvantages of other tested solutions. This equipment is suitable for various studies of the effects of laser interaction in biological tissues and not only, in photolithography, laser cleaning, for different techniques of identification etc.
The paper proposes an optical arrangement for the control in real-time of the laser spot position in lithography techniques. The arrangement is adequately for the small installation, especially used in research or teaching activities.
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