The SISCAL project (1), funded by the European Community, aims at promoting a user-friendly access to Earth Observation data products for end users concerned by monitoring the water quality of coastal areas and inland waters. This objective will be realized by the SISCAL processor which will offer, through the internet, EO data products, geographical information systems and a tool box for data analysis. We will present here this SISCAL prototype, its functionality and outputs from a validation exercise.

The SISCAL project aims to distribute near-real-time through internet ocean color and sea surface temperature data. To ensure the compatibility of the final products between different sensors, an in house algorithm was implemented, based on the "best" state of the art. We will deal here with the atmospheric correction module for the ocean color retrieval (and the upstream classification module). SeaWiFS data in coastal areas were processed using the SISCAL algorithm. This validation exercise of the algorithm brought some improvements to the algorithm: a better selection of the suitable pixels for aerosol remote sensing, the introduction of a background correction for clear days. We also raised the problem of the aerosol climatology through the regular existence of small aerosols which are never taking into account in the standard aerosol models used for atmospheric correction.

The time-space distribution of chlorophyll concentration in the gulf of Cadiz (SW Spain) is analysed by using remotely sensed data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) between 1998 and 2002. Climatological and monthly averages show more productive waters at the inner shelf, especially during winter-spring and fall blooms. This pattern is further confirmed by the modes obtained with an Empirical Orthogonal Function (EOF) decomposition of weekly chlorophyll composite images for the whole period. The first mode (10%) distinguishes several regions with patterns of variability correlated with oceanographic features in the area. It identifies a coastal zone between Huelva and Cadiz which is strongly coupled to local zonal winds where west and easterlies induce an increase and decrease of the chlorophyll respectively. Chlorophyll concentration of this area is also sensitive to precipitation.

Mapping the submerse vegetation is of prime importance for the ecological evaluation of an entire lake. Remote sensing techniques are efficient for such mapping tasks, if the retrieval algorithms and processing methods are robust and mostly independent from additional ground truth measurements. The Modular Inversion Program (MIP) follows this concept. It is a processing tool designed for the recovery of hydro-biological parameters from multi- and hyper-spectral remote sensing data. The architecture of the program consists of physical inversion schemes that derive bio-physical parameters from the measured radiance signal at the sensor. Program modules exist for the retrieval of aerosols, sun glitter correction, atmospheric corrections, retrieval of water constituents among others. For the purpose of mapping the bottom coverage in optically shallow waters, two modules have been added to MIP. The first module calculates the bottom reflectance using the subsurface reflectance, the depth and an approximation of the water constituent concentrations as input. The second module fractionalizes the bottom reflectance to three endmembers of specific reflectance spectra by linear unmixing. The three endmembers are specific reflectance spectra of bottom sediments, small growing macrophytes (Characeae) and tall macrophytes such as Potamogeton perfoliatus & P. pectinatus. The processing system has been tested with data collected from the multi-spectral airborne scanner Daedalus AADS1268 at Lake Constance, Germany, for multi- temporal analysis.

Marine pollution in the sensible North and Baltic Sea forces an international aerial surveillance. Within this framework the German aerial surveillance operates an advanced instrumentation on board of two 'Dornier 228’ aircrafts. The instrumentation consists of a set of state-of-the-art imaging remote sensors, like side looking airborne radar (SLAR), IR/UV line scanner and particularly a microwave radiometer (MWR) and a laser-fluoro-sensor (LFS). The most important aim is to detect oil discharges on the water surface, emitted accidentally or illegally. In case of discharge, the pollution has to be classified and quantified with a high accuracy. Another aim is to monitor biological and hydrological parameters, as there are the concentration of chlorophyll and dissolved organic matter (DOM) or the growth of phytoplancton. This paper describes the set of instruments and their potential to fulfill these demands. The SLAR operates to locate oil discharges and phytoplancton, whereas the IR/UV scanner allows to distinct the detected area. The IR/UV and especially the MWR sensor allow to quantify the thickness of the oil film. Finally, the LFS classifies the oil species as well as organic material. Emphasis is placed on the results of the sensor measurements and their synergy effects. The combination of the sensor data yields value added information for the operational users. An use of satellite data to improve the operational surveillance will be discussed. The potential and limitations of satellite and airborne data for the surveillance tasks will be compared.

The present work develops in the framework of the EU-ADIOS project for providing an estimate of the seasonal occurrence of Saharan dust events over the Mediterranean Sea. SeaDAS True Color (TC) images are used for monitoring dust. Dust identification has been carried out by visual inspection of TC images from 1998 up to 2002. The presence of dust, easily recognizable because of its color, is catalogued day by day. A grid representing a schematic division of the Mediterranean basin is overlaid to the TC images for a better identification and localization. The information retrieved by the cataloguing concerns space-time distribution of dust throughout the years examined. It is not possible to retrieve the intensity of the event by looking only at the TC images. Monthly values of Saharan dust load observed for each sector of the Mediterranean Basin for the period 2001 to 2002 have been retrieved from the Aerosol Optical Thickness maps for each dust day identified by the previous analysis. This is given in order to describe a spatial-temporal variability of the aerosol content. A brief description of the dataset, of the processing methodology and of the geophysical atmospheric products is also given.

In situ measurements of downward irradiance and upward radiance, together with determinations of surface concentrations of chlorophyll, suspended particles and colored dissolved organic material (CDOM) were made at 126 stations during 5 cruises in the Irish and Celtic Seas. Twenty one of these stations provided acceptable match-ups with SeaWiFS ocean color images. Normalized water leaving radiances for the selected stations derived from SeaWiFS data were well correlated with those measured at the sea surface (r² = 0.92). In situ observations from the whole region, which covered a wide range of water types including turbid coastal regions and a coccolithophore bloom, were therefore used to test the performance of SeaDAS algorithms for surface chlorophyll concentration (Chl) and the diffuse attenuation coefficient at 490 nm (K_d490). In general, Chl was over-estimated and K_d490 under-estimated by SeaDAS. However the algorithms performed acceptably in some regions such as St George’s Channel (r² = 0.70 for Chl, r² = 0.74 for K_d490). Examination of SeaWiFS and AVHRR images of this region for July 2002 revealed complex patterns of surface temperature and chlorophyll with a high degree of spatial correlation. The highest chlorophyll concentrations occurred on the stratified side of the Irish/Celtic Sea front.

A number of remote sensing instruments with multi-spectral imaging capabilities (SeaWiFS, MODIS, GLI on ADEOS-II, and others) have recently been launched on earth-orbiting satellites or will soon be launched into space. Many of these sensors offer unique opportunities for studies of sea ice and ocean properties at high latitudes. There are a number of challenges associated with the inversion of data received from satellite such instruments in order to retrieve meaningful information. Here we discuss some of these challenges with emphasis on the derivation of sea ice and marine parameters from satellite data.

Since 4th April 2001, Sea Surface Temperature (SST) of Azorean waters is obtained from 1.1 km resolution NOAA- 12, -14, and -16 imagery recorded at the “HAZO” HRTP mid-Atlantic satellite receiving station. One year of data is processed to investigate AVHRR-derived SST distributions and associated dominant space and time scales. Daily SST is calculated with the MultiChannel Sea Surface Temperature algorithm. Comparison with in situ historical data demonstrates that satellite SST ranges include low value pixels that may be attributed to undetected clouds. Images show that remnant clouds are associated to zones of strong cloud coverage. However, contamination of pixels in contact with clouds is found to be limited. Therefore, to remove erroneous values, rather than systematically erode pixels around clouds, images are filtered inputting to each image threshold values equal to the mean more or less 4 times the standard deviation of 8-day SST histograms. Nighttime SST averages show a distinct seasonal cycle for the Azores region. Increased surface heating and decreased horizontal gradients are found during summertime. Eight-day zonal and meridional SST averages show typical latitudinal and longitudinal gradients, providing some insight into the physical mechanisms responsible for surface temperature variability in the region. These data are relevant to improve stock assessment and fishery management studies in the Azores.

A full spectral third-generation ocean wind-wave model, Wavewatch-III has been implemented in the South China Sea (SCS) for investigating the wind wave characteristics. This model was developed at the Ocean Modeling Branch of the National Centers for Environmental Prediction (NCEP). The NASA QuickScat data (0.25° resolution) two times daily were used to simulate the wind waves for the whole year in 2000. The significant wave heights from Wavewatch-III are compared to the TOPEX/POSEIDON (T/P) significant wave height data over the satellite crossover points in SCS. The model errors of significant wave height have Gaussian-type distribution with small mean value of 0.02 m (almost no bias). The model errors are comparable to the T/P altimeter accuracy (0.5 m) om the central SCS and smaller than the T/P altimeter accuracy in the northern and southern SCS, which indicates the capability of Wavewatch-III for SCS wave simulation.

Sea surface salinity (SSS) measurement is one of the objectives of ESA’s SMOS (Soil Moisture and Ocean Salinity) Earth Explorer Opportunity mission. SMOS’s objective is to provide global soil moisture and sea salinity maps using the MIRAS L-band aperture synthesis interferometric radiometer. Since the sea salinity signature exhibits a very small brightness temperature dynamic margin, it can only be accurately retrieved if the sea surface emissivity at L-band is properly modeled. In addition to the sea salinity signature, other factors influencing the emissivity are the sea surface temperature, and the sea surface roughness induced by wind, the large scale roughness created by swell, and the foam emissivity. This article is focused on the estimation of the sea surface spectrum, which describes sea roughness, training a neural network with wind and roughness data obtained during WISE 2000/2001 (WInd and Salinity Experiment).

An algorithm is introduced, which is designed to retrieve high-resolution wind fields from C-band synthetic aperture radars (SAR) operating at both vertical and horizontal polarization. The wind directions are extracted from wind-induced streaks, which are approximately in line with the mean wind direction near to the ocean surface. The wind speeds are derived from the normalized radar cross section (NRCS) and image geometry of the calibrated SAR images, together with the local wind direction retrieved from the image. Therefore the semi empirical C-band model CMOD4, which describes the dependency of the NRCS on wind and image geometry, is used. The CMOD4 was originally developed for the scatterometer of the European remote sensing satellites ERS-1 and 2 operating at C-band with vertical polarization. Consequently CMOD4 requires modification for horizontal polarization, which is performed by considering the polarization ratio. To verify the algorithm, wind fields were computed from the European satellites ERS-1/2 and ENVISAT SAR as well as the Canadian satellite RADARSAT-1 and compared to results from numerical models and a scatterometer.

From raw ERS wavemode data, complex SAR images of size 5 km x 10 km - so called imagettes - are computed using DLR's BSAR processor. Being collected over oceans every 200 km along the orbit, imagettes provide a patchy daily global coverage of the world's oceans. This paper presents DLR's processing chain and results for a three week testing period covering the detection of ocean slicks and sea ice, the use of cross spectra to derive wave spectra over open ocean, the detection of one or several ocean wave systems together with its wave length and its propagation direction, and the estimation of single wave heights. In sea ice covered areas, statistical parameters derived from the SAR are well correlated to physical measures such as the ice deformation energy and ridge frequency. Over ice free areas, comparisons between the SAR results and the ECMWF analysis as well as model results show good agreement in most cases. Observed deviations between SAR measurements and model results are discussed. As a new application of wave mode data statistics are presented on the occurence of extreme waves. As soon as ESA will make available the daily global raw wavemode data for the whole lifetime of ERS-1 and ERS-2, it will be possible to DLR to derive unique statistics on sea ice and wave parameters for a period of at least 10 years, which may be even extended by the use of ENVISAT data in future. Together with near surface wind fields which are also derivable from the imagettes, this work will be of extreme use for climate research applications.

The possibility to retrieve parameters of a current from radar data is under investigation. The study is based on ERS SAR and TU-134 RAR images. It is well-known that currents are difficult to detect directly in radar images. However, it is often possible to detect current manifestation by its impact on internal wave field, by the character of “wake-like” features and vortex streets behind islands, and by spatial pattern of natural and oil slicks. Observation of internal waves transformation by nonuniform large-scale currents are considered. Specific manifestations of internal waves front distortions can be caused by following phenomenon: the influence of bottom relief, variability of water density, wave-wave interaction and refraction on the horizontally nonuniform large-scale currents. Radar data clearly demonstrate unusual disturbances of internal solitons fronts, which cannot be explained by bottom topography. The theoretical considerations show that the influence of stratification variability is weakly than the currents influence. For that, we assume that observed distortions of internal waves fronts are caused by transformation on the oceanic currents. Available radar images obtained in the Bering Strait display a large variety of surface manifestations of vortex streets behind the Fairway Rock and lee waves behind Diomede Islands connected with the variability of the run-against flow. Based on well-known theoretical hypothesis, results of laboratory experiments, and analysis of radar data the estimation of speed and direction of sea currents has been done. Summer/autumn concurrent experiments conducted near Gelendzhik, Black Sea shore, allowed to qualitatively estimate the sea current characteristics by means of analysis of surface slick manifestations on radar data.

A global daily altimetry dataset was recently established at the Naval Research Laboratory on the base of Geosat Follow-On, TOPEX/POSEIDON, and ERS-2 data using the Modular Ocean Data Assimilation System (MODAS). After quality control such as tidal and orbit error removal, referencing to a consistent mean, it provides a global sea surface height (SSH) data with high temporal and spatial resolutions. We identify the first baroclinic Rossby waves wtih a phase speed around 3-5 cm/s in the northern South China Sea using 1994-2001 daily SSH data. We also find that there is no evident Rossby wave signal in the southern South China Sea.

TOPEX/Poseidon altimeter data are used to estimate anomalies of water transport in summer through Bering Strait from September 1992 until November 2001. The detided altimeter data show significant changes in sea level in this area associated with storm surges in adjacent shallow seas. These large signals tend to mask the loweramplitude seasonal and interannual sea level variability. However, it is possible to compute intra-seasonal and interannual changes in the northward geostropic flow through the strait from the cross-strait sea level gradients as measured by the TOPEX/Poseidon altimeter.

Previous studies of the Mediterranean outflow and meddies (O&M) were limited by poor spatial and temporal resolution of the conventional observations. Little is known about meddies formation and transport, and the spatial and temporal variation of its trajectories. Generally speaking, most of the satellite observations are confined to the ocean's surface or its surface layer, while meddies were located, on an average, at a depth of 1000m. We developed a new remote sensing method to observe and study the O&M through unique approaches in satellite multi-sensor data integration analyses. Satellite altimeter, scatterometer, SST and XBT data were used to detect and calculate the trajectories and the relative transport of the O&M. We found that more northwestward meddies occurred in the spring and more southward meddies occurred in the fall than previously thought. Since the O&M play a significant role in carrying salty water from the Mediterranean into the Atlantic and contribute to the North Atlantic Deep Water (NADW) formation, such new knowledge about their trajectories, transport and life histories is important to understand their mixing and interaction with the North Atlantic water, adn hence, to lead to a better understanding of the global ocean circulation and the global change.

The monthly mean TOPEX/POSEIDON crossover data in the South China Sea are used to investigate the spatial and temporal variability of sea surface height anomaly (SSHA). Multi-time scale variability is found using the empirical orthogonal function (EOF) analysis. The seasonal variability dominates SSHA with two spatial patterns: basin-wide gyre and north-south double gyres. The intraseasonal variability of SSH has high spatial variability at the continental s helf such as west of Hainan Island and Borneo, and east-west double gyre structure in the deep basin. The interannual variability of SSHA has a north-south double gyre pattern. The scale interaction between seasonal interannual processes may be taken at the north-south double gyre pattern.

Different methods for the extrapolation of vertical profiles from sea surface measurements are presented. The techniques, called Coupled Pattern Reconstruction (CPR) and multivariate EOF Reconstruction (mEOF-R) base on the multivariate analysis of the variability of vertical profiles from hydrographic data and on the hypothesis that only few modes are needed to explain most of the variance/covariance of the fields. The CPR and mEOF-R methods have been applied and tested on the data collected during SYMPLEX survey in a selected area of the Mediterranean sea (the Channel of Sicily), also using simultaneous altimeter measurements as surface input.

For optical satellite remote sensing of the marine arctic environment it is essential to establish appropriate knowledge of its optical properties. To that end we used a multi stream radiative transfer (RT) code to study the penetration of spectral irradiances in a coupled atmosphere-ice-ocean system. The code account for the change in the refractive index at the atmosphere-ice interface. To validate and tune this coupled RT model we ran the code with input from in situ measurements of optical properties and compared the computed results with in situ spectral irradiance measurements. The field work was done in Kongsfjorden, Svalbard, and the measurements were performed for first year ice. One goal of this study was to establish a model for the optical properties of the marine arctic environment that can be used in the interpretation of satellite remote sensing data.

Inland waters are an increasingly valuable natural resource with major impacts and benefits for population and environment. As the spatial resolution is improved for “ocean color” satellite sensors, such observations become relevant to monitor water quality for lakes. We first demonstrated that the required atmospheric correction cannot be conducted using the standard algorithms developed for ocean. The ocean color sensors have spectral bands that allow characterization of aerosol over dark land pixels (vegetation in the blue and in the red spectral bands). It is possible to use a representative aerosol model in the atmospheric correction over inland waters after validating the spatial homogeneity of the aerosol model in the lake vicinity. The performance of this new algorithm is illustrated on SeaWiFS scenes of the Balaton (Hungary) and the Constance (Germany) lakes. We illustrated the good spatial homogeneity of the aerosols and the meaningfulness of the water leaving radiances derived over these two lakes. We also addressed the specificity of the computation of the Fresnel reflection. The direct to diffuse term of this Fresnel contribution is reduced because of the limited size of the lake. Based on the primary scattering approximation, we propose a simple formulation of this component.

Thermal satellite images relative to the years 1997-2000 are analyzed in this study, in order to infer cold filament and surface jet dynamics in the Mediterranean Sea. The main zones in which these phenomena are seen to occur, are characterised by upwelling and/or the funnelling of strong cold winds by a somewhat irregular coastal orography. Indeed, intense air-sea interaction in the coastal zone is known to generate a particularly strong input of potential vorticity into the sea, and this in turn gives origin to upwellings, cold filaments and jets. In the Mediterranean Sea the geographical zones with a higher frequency in these jets are the two lobes of the southern Sicilian coast, the sea off Olbia in Eastern Sardinia, that south of the island of Crete where a particularly intense large scale turbulence field is evident, and the Balkanic coast of the Adriatic Sea. In addition the theoretical analysis of these jets' evolution using a modern version of the potential vorticity conservation, valid even if friction and entrainment are considered, gives further insight into these systems’ dynamics.

The creation and rendering of realistic water scenes is one of the challenging tasks in Computer Graphics. To reproduce the illumination and color inside water bodies an algorithm capable of dealing with media with anisotropic and multiple scattering has to be used. We have developed a simulation system, CORDIS, based in the discrete ordinates method to solve the problem of light transport in general participating media. The system is adequate to treat complex participating medium such as natural waters as it is prepared to deal with, not only anisotropic, but highly-peaked phase functions as well as to considered the spectral behavior of the medium’s characteristic parameters. It is also able to generate not only synthetic images but detailed quantitative illumination information, so as the amount of light that reaches the medium boundaries or the amount of light absorbed in each of the medium voxels. The system considers objects and light sources inside the water, works with realistic spectral medium parametrizations (bio-optical models) and can be extended to consider not only elastic but inelastic processes such as fluorescence.

Modeled hyperspectral reflectance signatures just above the water surface are obtained from an analytical radiative transport model applicable to shallow water types. Light transport within the water body is simulated using a fast, accurate radiative transfer model that calculates the light distribution in any layered media. A realistic water surface is synthesized using empirically-based statistical models of ocean surface waves. Images are displayed as 24 bit RGB images of the water surface using selected channels. The selected channels are centered at 480, 520 and 650 nm. Hyperspectral image cubes with two spatial and a third spectral dimension are shown to allow the detection of any optically unresolved features in the two-dimensional RGB image.

Two field experiments named WISE (WInd and Salinity Experiment) were sponsored by the European Space Agency (ESA) to better understand the wind and sea state effects on the L-band brightness temperatures. They took place at the Casablanca oil rig located in the North Mediterranean Sea, 40 km off shore the Ebro river delta: WISE 2000 from November 25 to December 18, 2000, and continued during the January 9 to 16, 2001, and WISE 2001 from October 23 to November 22, 2001. During the spring of 2003, under Spanish National funds, a third field experiment named FROG (Foam, Rain, Oil slicks and GPS reflectometry) took place at the Ebro river delta, to measure the phenomena that were not completely understood during the WISE field experiments, mainly the effect of foam and rain. In order to achieve the objectives of the WISE field experiments the LAURA L-band fully polarimetric radiometer from the Technical University of Catalonia (UPC) was mounted on the Casablanca oil-rig at the 32 meters deck above the sea surface, pointing to the North and North-West, in the direction of the dominant winds. In this paper we present the results of the first study to determine the relationship between the brightness temperature and the sea state.

The main goal of this study is to derive information on parameters characterizing airflows over the sea surface, particularly downwind natural obstacles from the analysis of SAR imagery. A series of ERS-2 SAR images of the sea surface recorded over north-eastern part of the Black Sea near the Caucasus coast is considered. This set of radar data has been collected in various seasons during 4 years. Related meteorological data, weather and cloudiness maps are available. A distinctive feature of the region is the mountain ridge stretched along shore and having a complicated structure with multiple canyons opening to the sea. Depending on the airflow characteristics radar images of sea surface can bear imprints associated with convection, internal waves in atmosphere, air jets, mushroom-like flows, lee waves, vortices, etc. Radar image patterns are investigated in relation to airflow speed and direction, boundary layer stratification and local topography.

An operational fisheries oceanography system was established to help fishermen analyze the situations of fishery in North Pacific. The system composes of three sub-systems which are a ship-boarding satellite telemetry receiving station, a ship-boarding satellite communication system and a land-based fishery charts producing system. The system can provide some oceanic environmental charts such as sea surface temperature (SST) and relevant derived products which are the most popular use in fishery industry. The accuracy of SST is the most important and affects the performance of the operational system, which is found to be dissatisfactory. Many factors affect the accuracy of SST and it is difficult to increase the accuracy by SST retrieval algorithms and clouds detection techniques. A new technique of temperature error control is developed to detect the abnormity of satellite SST. The performance is evaluated to change the temperature bias from -3.04 to 0.05°C and the root mean square (RMS) from 5.71 to 1.75°C. It is suitable to be employed in an operational satellite-measured SST system and improves the performance of the system in fishery applications.

In the frame of the EC-funded project SISCAL (Satellite-based Information System on Coastal Areas and Lakes), in situ campaigns have been executed in three coastal areas in the Baltic Sea, North-Eastern Atlantic and the Eastern Mediterranean as well as in a lake in North-Eastern Germany. The aim of these campaigns was to obtain measurements of the chlorophyll concentration for the validation of MERIS (Medium Resolution Imaging Spectrometer) data products. Between May and September 2002, in situ measurements have been performed concomitantly to thirteen MERIS overpasses. As of December 2002, MERIS Level-2 ocean products could be made available for six of the thirteen overpasses. At the specific in situ sampling sites, ocean products were available in four of the six MERIS data sets. On a pixel-by-pixel basis, three / four match-ups are available for Algal Pigment Index (API) I / II. The following preliminary conclusions can be drawn from the SISCAL validation activities: 1) API I shows a better dynamic resolution than does API II and reveals such more detailed dynamic structure, especially in oligotrophic areas, 2) in open ocean areas, API II values are larger (mostly by a factor of roughly two) than the API I values and appear to be overestimated, 3) in coastal areas influenced by significant CDOM concentrations, API II gives better results than API I.

Remote sensing represent a powerful tool to estimate chla concentrations and to predict primary production in coastal waters. However, in order to use this tool efficiently in such variable ecosystems we need to increase our knowledge concerning bio-optical properties, phytoplankton community and photosynthetic parameters variability in order to develop adapted regional algorithms. Spatial and temporal variations of these key parameters were investigated during spring 2000 in the English Channel across five mesoscale cruises (BIOPTEL) realised between February and October 2000. From this in situ data set (phytoplankton pigments obtained by HPLC, nutrients concentration, phytoplankton productivity estimated by variable fluorescence technique (Phyto-Pam), yellow substance absorption, particulate matter absorption), we assessed the scales of variation of primary production model inputs in the several identified biological provinces and throughout spring. These in situ observations were used to proceed to sensitivity analyses of a local primary production model. Further, from this local modelisation we discussed on (i) the biases induced by the using of existing algorithms developed to obtain primary production directly from satellite data in such ecosystems and (ii) of the improvements which should be done concerning such general models.

The real sea level response to atmospheric pressure variations is quantified and compared with the one deduced from the isostatic assumption, which is normally used to correct the effect of the atmospheric pressure oscillations in the ocean, the so-called Inverse Barometer Correction (IBC). We have analysed the first four years of ERS-2 altimetric records in the Mediterranean Sea. We obtained the regression coefficients at each geographical point of the satellite tracks and in the crossover track points, estimating the relation between the surface atmospheric pressure and the sea level anomalies. The geographical distribution of the regression coefficients obtained, demonstrates that there are important local deviations from the hypothetical value (-0.998 cm/bar), being more evident when we reduce the time sampling from 35 days to 10.5 days. We have obtained the variance associated to the inverse barometer correction, and the one obtained by using the individual regression coefficients obtained at each geographical position in both, collinear and crossover method. We observe a variance reduction of approximately 30% in the sea level anomalies series, when barometric corrections are applied, in the case of collinear track method, and around 15% when we use the crossover track method. We have also quantified the difference in the variance reduction of the sea level anomalies when the standard IBC and the atmospheric pressure correction (use of the regression coefficients estimated on each geographical position, instead of the isostatic value: -0.998 cm/mbar) are applied. We also observe a reduction of approximately 2% in the variance when the atmospheric correction is applied, instead of IBC (in both cases, CM and XM).

The thermal radiation of rough water surface in small-scale approximation is considered. The mathematical model of radiating ability of multiwave perturbation is based on the Kirchhoff law of radiation, Leontovich boundary conditions and small perturbations method. The experimental research of radiating properties of the rough water surface mock-up is carried out. The critical phenomena were revealed as increase of a thermal radiation in the certain allocated spatial directions.

The current request of a minimum precision of ± 0.3 K in the sea surface temperature for climate studies and the use of high observation angles in the present space missions require a thorough analysis of sea surface emissivity (SSE) and its angular dependence. In this paper, we present SSE experimental values determined from thermal infrared radiometric measurements carried out from an oilrig under open Mediterranean conditions during the WInd and Salinity Experiment 2000 campaign (WISE 2000) founded by ESA. The methodology consists of quasi-simultaneous measurements of the radiance coming from the sea surface and the downwelling sky radiance, in addition to the corresponding sea temperature as reference. Radiometric data were taken by a CE 312 radiometer, with 4 channels placed in the 8-14 μm interval. Sea temperature was measured with high-precision thermal probes located on oceanographic buoys. SSE was obtained under several observation angles and surface wind speed conditions, allowing us to study both angular and sea surface roughness dependence. SSE decreases 2% - 3% for 55°. Finally, we compare our results with several theoretical models, showing the validity of the Masuda et al. (1988) model for observation angles up to 50°. For higher angles, the effect of possible double or multiple reflections on the sea surface produces discrepancies between measured and theoretical SSEs, such as Wu and Smith (1997) advised.

Eddies generated by the Canary Current south of Canary Islands when the flow passes through the archipelago define a high mesoscale variability of the sea level downstream of the islands. Evidence of zonal propagation of perturbations of sea surface heights was observed by generating longitude-time plots. Hovmoeller diagrams of the altimetric data for 1997 and 1998 at 27°N (south of Cape Jubi), 26°N (Cape Bojador) and 25°N (south of Cape Bojador) are analysed. Both cyclones and anticyclones were observed in the satellite data as anomalies originating south of Gran Canaria or Tenerife islands and moving southward of Gomera and El Hierro islands. The sea level variability associated with these mesoscale features, has the highest intensity during summer and autumn, when Trade winds and incident currents are stronger. An anticyclonic eddy observed in December 1997 is described on the basis of sea level anomalies deduced from ERS-2 altimetry and sea surface temperature data. This mesoscale oceanographic feature was tracked approximately 3 months (november - february), decreasing a the sea surface elevation from 25 cm registered at the end of november at 26.5°N to 15 cm in february. During this period the vortex is moved southwest at 1.7 km/day. Comparisons between sea level anomalies from altimetry and sea surface temperature images from AVHRR agree that the eddy was moved and modified its characteristics during this period.

Sea surface temperature can be estimated from infrared satellite radiances. The NOAA-AVHRR radiometer has been used to produce SST fields during the last decades. The aim of this study is to examine, with Pathfinder Oceans Matchup Database, the SST accuracy deviations that occur when we use in situ data from different latitudinal and longitudinal bands to compute, by linear regression, the NLSST algorithm coefficients. We have restricted the in situ SST to 8 latitudinal bands and 18 longitudinal bands. Applying the resulting coefficients of the equatorial region (20N to 20S) and from the polar zone to the global case, we have found that the mean of residuals (SST in situ minus estimated SST) is greater than -0.6°C and the standard deviation near to 1°C in both cases. When we use the coefficients from longitudinal bands in global data set, the residuals show a bias lower than -0.1°C in about the 80% of cases. We conclude that the mean errors for the longitudinal algorithms are small when compared to the latitudinal, but in both cases have a substantial dependence on the SST in situ.

Primary Production (PP) has been estimated in the Mediterranean Sea from SeaWiFS data for the years 1998-2001 adapting a model developed by Antoine et al. (1996) to Mediterranean conditions. The tuning is based on the use of a new large data set of chlorophyll profiles acquired during the last 10 years in the Mediterranean Sea. Moreover a new data set of cloud cover and temperature has been used and SeaWiFS derived chlorophyll has been estimated using a Mediterranean algorithm recently proposed by D’Ortenzio et al. (2002). Comparison between present model estimates, previous models estimates and in situ data gives satisfactory results and show that the adapted model better reproduces the PP seasonal trend of Mediterranean Sea. The application of the procedure to each pixel of single SeaWiFS images allows the creation of daily, weekly and monthly averaged estimates of depth-integrated PP.

The Satellite Oceanography Group (GOS) of Rome developed a system that provides satellite ocean colour images and data on the web. This meets the growing demand for near real-time ocean colour products for applications in operational oceanography. The system has been developed to produce: 1) fast delivery images for monitoring applications and operational support on oceanographic cruises; 2) accurate ocean colour products for data assimilation on ecosystem model. Real Time Images of SeaWiFS chlorophyll concentration, clouds/case I/case II water flags and true color images are obtained by processing the satellite passes using climatological ancillary data. These images are provided daily through an ad hoc automatic procedure that processes the raw satellite data and makes it available on the web within an hour after the acquisition. All the images are stored in a gallery archive organized in a calendar chart for the selection of the images to display. On the opposite, accurate chlorophyll maps for assimilation in numerical models are produced in near real time (typically after 4 days) as soon as daily meteorological ancillary data are made available on the NASA website. Each chlorophyll map is flagged for clouds or other contamination factors using the corresponding 24 quality flag maps. This implies that case-2 waters and possible contaminations of chlorophyll have been implicitly removed. This final product is binned on Adriatic model grid and made available to ADRICOSM project on GOS web site. These daily chlorophyll maps are assimilated by ADRICOSM modeling group to provide the forecasting of Adriatic ecosystem.

The purpose of this paper is to present results of simulations of the Florida Tech UTC-M sea-breeze model with the addition of a simplified atmospheric downwelling radiation subroutine combined and a thermal inertia subroutine into the atmospheric planetary boundary layer model, in order to calculate time dependant heat flux boundary conditions at the air-land boundary that are derived from satellite data from AVHRR and MODIS sensors. The improved UTC-M planetary boundary layer model with this thermal sub-model subroutine is used to demonstrate the use of thermal inertia to help estimate heat fluxes at the land-air interface which in turn influences convergence and vertical fluxes near the bottom boundary, and which may affect mesoscale meteorological wind and seabreeze over complex land-water margins. Additionally, message passage interface (MPI) parallelizing Fortran techniques were used to improve the computational time when the model grid was decreased down to 2 or 1 km cell when simulations where performed on the FIT supercomputer based on an IBM Beowulf Linux cluster. We present some results of the UTC-M simulations and associated results due to the influence of the parameterization of the net surface radiation and thermal inertia using the spectral or wavelength (channel) specific data from MODIS and AVHRR satellite sensors.

A pushbroom sensor motion control system was developed for use in conjunction with a pulsed laser fan beam, streak tube camera, and a high speed low light level camera . The LIDAR and camera control system was tested to study the influence of water waves upon active-passive remote sensing systems and associated models that require pushbroom sensor motion. A pulsed laser fan beam signal at 532 nm was recorded using a streak tube camera and a (high speed, low light level, high quantum efficiency) digital CCD camera. Tests were conducted in 3 different water tanks, including 2 tanks with water waves (the longest wave tank or channel is 60 m long). Capillary waves, ~1 cm wavelength) were generated using an acoustic wave source generator. Streak tube camera and CCD images were collected in conjunction with a 532 nm pico-second short pulse laser. Images collected demonstrate the pulse stretching around submerged water targets as well as the ability to discriminate water depth of submerged targets in shallow water types. In turbid water, the pulsed layer backscatter structure showed a nearly random return as a function of depth if the signal was attenuated before reaching the bottom of the water column. The data collected indicated the motion control testing system can accommodate a variety of cameras and instruments in the lab and in the outdoor water wave channel. Data from these camera systems are being used to help validate analytical and Monte Carlo models of the water surface structure, and the underwater light field structure (pulse stretching) as well as to validate other LIDAR applications used in bathymetric and hydrographic surveys of coastal waters and marine inlets for physical and biological (submerged vegetation) surveys.

Submerged aquatic vegetation (SAV) is an important indicator of freshwater and marine water quality in almost all shallow water aquatic environments. Throughout the world the diversity of submerged aquatic vegetation appears to be in decline, although sufficient historical data, of sufficient quantitative quality is lacking. Hyperspectral remote sensing technology, available from low altitude aircraft sensors, may provide a basis to improve upon existing photographic regional assessments and monitoring concerned with the aerial extent and coverage of SAV. In addition, modern low altitude remote sensing may also help in the development of environmental satellite requirements for future satellite payloads. This paper documents several important spectral reflectance signature features which may be useful in developing a protocol for remote sensing of SAV, and which is transferable to other shallow water aquatic habitats around the world. Specifically, we show that the shape or curvature of the spectral reflectance absorption feature centered near the chlorophyll absorption region of ~ 675 nm is strongly influenced not only by the relative backscatter region between 530-560 nm, but by a “submerged vegetation red edge” that appears in the 695 to 700 nm region in extremely high density vegetative areas in very shallow waters (= 0.5m depth). This “aquatic biomass red edge” is also observable in deeper waters where there is a shallow subsurface algal boom as demonstrated in this paper. Use of this submerged aquatic red edge feature will become an important component of SAV remote sensing in shallow aquatic habitats, as well as in phytoplankton-related water quality remote sensing applications of surface phytoplankton blooms.