In the southern South America, various types of aerosols have been observed including biomass burning aerosols from the Amazon region, flying ashes from the volcanic eruptions coming from the Andean Volcanic Belt, mineral dust from the Patagonian Desert, and air pollution aerosols from urban areas. To monitor such aerosols continuously, we developed a lidar observation network in Argentina and Chile. Eight lidars were installed in Argentina and one in Punta Arenas, Chile. Backscattering signals are measured at three wavelengths: 355, 532, and 1064 nm. Eight of those instruments are measuring depolarization ratio at 355 and 532 nm to detect non-spherical aerosols. In addition, four lidars are equipped Ramans channels and two high-spectral-resolution channels to measure backscattering and extinction coefficients quantitatively. Lidar operation, data analysis, and products release are implemented within the South American Environmental Risk Management Network (SAVER-Net) system, which was developed by a trinational project among Japan, Argentina, and Chile. Using lidar data, hazard information on the aerosol type and extinction coefficient at low altitude is provided for public in a near real time. In addition, plume height and qualitatively concentration for volcanic ashes are estimated. The information on volcanic ashes may be effectively used for advising aircraft landing and departing when volcanic eruptions occurs.
Continuous monitoring of aerosol profiles using lidar is helpful for a quasi-real-time indication of aerosol concentration. For instance, volcanic ash concentration and its height distribution are essential information for plane flights. Depolarization ratio and multi-wavelength measurements are useful for characterizing aerosol types such as volcanic ash, smoke, dust, sea-salt, and air pollution aerosols. High spectral resolution lidar (HSRL) and Raman scattering lidar can contribute to such aerosol characterization significantly since extinction coefficients can be measured independently from backscattering coefficients. In particular, HSRL can measure aerosol extinction during daytime and nighttime with a high sensitivity. We developed an HSRL with the iodine filter method for continuous observation of aerosols at 532nm in the northern region of Argentina in the framework of the South American Environmental Atmospheric Risk Management Network (SAVER.Net)/SATREPS project. The laser wavelength of the HSRL was controlled by a feedback system to tune the laser wavelength to the center of an iodine absorption line. The stability of the laser wavelength with the system satisfied the requirement showing very small systematic errors in the retrieval of extinction and backscatter.
Atmospheric monitoring stations are being developed in Argentina. The most important targets are volcanic ashes, desert aerosols in particular Patagonian dust and biomass burning aerosols. Six stations deployed in the Patagonian Region and Buenos Aires have lidar systems, sun photometers integrated to the AERONET/NASA monitoring network, in situ optical particle analyzers, four solar radiation sensors (pyranometer, UVA, UVB and GUV), and meteorological equipment. The stations are in the main international airports of the Regions (San Carlos de Bariloche, Comodoro Rivadavia, Neuquén, Rio Gallegos) and in Buenos Aires (Aeroparque Jorge Newbery and at CEILAP/CITEDEF). CEILAP and the National Institute of Environmental Studies (NIES) at Tsukuba, Japan developed the first iodine cell-based high spectral resolution lidar (HSRL) in Argentina to add in the lidar network. We upgraded the standard CEILAP multi-wavelength Raman lidar adding the laser frequency tuning system and the 532 iodine-filtered channel at the reception to built the HSRL. HSRL will provide daytime and nighttime direct observation of the aerosol and cloud optical properties (backscatter and extinction) without the pre-assumption of the lidar ratio. This work shows the design and construction of the first Argentinean HSRL. We also show the first lidar observations done in the country with this kind of lidar.
The Latin American Lidar Network (LALINET) is the aerosol lidar network operating over South America. LALINET is now an operative network performing a schedule of routine measurements and, currently, is composed by 9 stations distributed over South America. The main objective of LALINET is to generate a consistent and statistically relevant database to enhance the understanding of the particle distribution over the continent and its direct and indirect influence on climate. The creation of an un-biased spatiotemporal database requires a throughout review of the network on two pillars: instrumentation and data processing. Because most of the LALINET systems are not series-produced instruments and, therefore, present large differences in configuration and capabilities, attempts for network harmonization and, consequently, optimization are mandatory. In this study a review of the current instrumental status of all LALINET systems is done and analyzed in detail in order to assess the potential performance of the network and to detect networking weaknesses.
As part of environmental studies of the southern atmosphere, the CEILAP Lidar Division in collaboration with the Service d'Aeronomie has developed a mobile differential absorption lidar capable of making precise and accurate measurements of the stratospheric ozone. The XeCl excimer laser emission at 308 nm is used as absorbed line in the DIAL technique and an Nd-YAG laser 355 nm third harmonic is employed as a reference wavelength. Six detected channels are used for stratospheric ozone retrieval, four of them in the high and low energy of the elastically backscattered signal of the emitted wavelengths and two corresponding to the first Stokes nitrogen Raman of the emitted wavelengths. Tropospheric Water Vapor profiles using Raman channels and Aerosol Backscatter profiles are also obtained. In this paper we present a detailed description of the instrument, a discussion of data analysis and the results of the first lidar-satellite inter-comparison of stratospheric ozone profiles measured with this instrument. We also present a description of the SOLAR campaign that will be held in the 2005 southern winter-spring period in Rio Gallegos (51° 55'S, 69° 14'W) with the objective of studying the ozone layer when the polar vortex crosses over the continental part of Argentina. This campaign will be supported by JICA (Japan International Cooperation Agency).
An intensive study of an aerosol intrusion episode in Buenos Aires is presented. We have combined back-trajectories calculations (HYSPLIT) and satellite images with the aim of revealing the origin of these air masses. The aerosol intensive properties were characterized using a collocated sun-photometer from the AERONET network. The corresponding pressure levels for each air mass were obtained by means of a LIDAR system, which was also used to calculate the aerosol extinction profiles for the available wavelengths.
The lidar systems contribute with privileged information to study environmental pollution due to its capacity to discriminate different atmospheric parameters in time and space. In this work, three of those system were developed at CEILAP laboratory in Argentina (34° 33' S, 58° 30' W): 1) a Multiwavelength lidar to characterized the atmospheric boundary layer and tropospheric aerosols using a Nd:YAG laser (10 Hz, 650 mJ @ 1064 nm); 2) a Raman lidar to measure night-time water vapor profiles, useful as a tracer of air parcel and in understanding energy transport within the atmosphere. This system utilizes an excimer laser (XeCl) (100 Hz, 300 mJ @ 308 nm), and 3) a differential absorption lidar (DIAL) to measure the stratospheric ozone profile. Two laser are used, the same excimer laser of Raman lidar and a Nd:YAG laser (30 Hz, 950 mJ @ 1064 nm). Complementary in situ measurements are also performed with a sun-photometer (AERONET-NASA); UVA, UVB and GUV radiometers (Argentina Solar Monitoring Network), pyranometer and a pyrgeometer. Recent results and the synergy between the actives and passives instruments are showed.
The solar radiation at Earth surface is measured usually with instruments of narrow or large wavelengths bands. However, for different applications like the determination of irradiances related to biological actions and substance and material degradations, it is needed to know the spectrum at all wavelengths with reasonable resolution. In CEILAP (CONICET - CITEFA) placed at the Gran Buenos Aires suburbs (34° 33' S, 58° 30' W, 20 m asl), we made measurements of solar UV irradiance in clear sky days in the UV range (300 - 400 nm) range with a spectroradiometer Monospec 27 of National University of Rosario. The data represented in a 3D diagram show the variations in the solar spectrum along the day as function of the solar zenith angle. From the comparison with the results obtained employing the TUV program developed by Madronich/NCAR that solves the radiative transfer equation, it is possible to determine the influence of the ozone and aerosol atmospheric components on this irradiance. The spectra were calibrated against the absolute measurements made with an instrument GUV 541 at wavelengths of 305, 320, 340 and 380 nm, which is placed in the same building and was recently calibrated.
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