Remote sensing instruments provide a huge volume of measurements of sea surface parameters which are of fundamental interest to the oceanographic community, mainly because of the high spatial and temporal coverage of satellite sensors respect to traditional techniques. In fact, the whole ocean circulation is actually driven by processes occurring at the air-sea interface, as the energy is mainly supplied to the ocean by atmosphere-ocean interactions. Consequently, altimeter derived SSH and SST obtained from AVHRR, that have already proved to be quit useful to evaluate the sea surface variability, can be though t as possible tools to investigate the ocean dynamics and atmosphere-ocean interaction more deeply. In this work, 2 years of Mediterranean Forecasting System Pilot Project dat over the Mediterranean basin are analyzed. The relationship between SST and SLA is investigated applying an objective method for coupled pattern detection, based on the singular value decomposition of the covariance of the two data-sets.

Nowadays, satellites are the only monitoring systems that cover almost continuously all possible ocean areas and are now an essential part of operational oceanography. A novel approach based on artificial intelligence (AI) concepts, exploits pasts time series of satellite images to infer near future ocean conditions at the surface by neural networks and genetic algorithms. The size of the AI problem is drastically reduced by splitting the spatio-temporal variability contained in the remote sensing data by using empirical orthogonal function (EOF) decomposition. The problem of forecasting the dynamics of a 2D surface field can thus be reduced by selecting the most relevant empirical modes, and non-linear time series predictors are then applied on the amplitudes only. In the present case study, we use altimetric maps of the Mediterranean Sea, combining TOPEX-POSEIDON and ERS-1/2 data for the period 1992 to 1997. The learning procedure is applied to each mode individually. The final forecast is then reconstructed form the EOFs and the forecasted amplitudes and compared to the real observed field for validation of the method.

The aim of the SOFT project is to develop a new ocean forecasting system by using a combination of satellite dat, evolutionary programming and numerical ocean models. To achieve this objective two steps are proved: (1) to obtain an accurate ocean forecasting system using genetic algorithms based on satellite data; and (2) to integrate the above new system into existing deterministic numerical models. Evolutionary programming will be employed to build 'intelligent' systems that, learning form the past ocean variability and considering the present ocean state, will be able to infer near future ocean conditions. Validation of the forecast skill will be carried out by comparing the forecasts fields with satellite and in situ observations. Validation with satellite observations will provide the expected errors in the forecasting system. Validation with in situ data will indicate the capabilities of the satellite based forecast information to improve the performance of the numerical ocean models. This later validation will be accomplished considering in situ measurements in a specific oceanographic area at two different periods of time. The first set of observations will be employed to feed the hybrid systems while the second set will be used to validate the hybrid and traditional numerical model results.

Spaceborne SAR provides key information on the nature, distribution and evolution of sea ice, to assist operational applications in polar waters. Concurrent in situ dat are not generally available in such cases. Here, we discuss the development of a radar backscatter model which can assist the interpretation of SAR data under such circumstances. We define the model parameters from the results of measurement campaigns in different seasons over the region of interest. However, some key parameters require the use of investigations at other sites, laboratory studies and previous investigations with radar data. Here we discus the model development for sea ice in the Weddell Sea, Antarctica. We use second-order radiative transfer theory, incorporating both volume and surface scattering. A surface snow layer is included, and seasonal dependancies are studied. We consider the predicted behavior for first-year and multi-year ice. We assess ERS and RADARSAT SAR images and ERS scatterometer data. Polarimetric SAR observations from the Shuttle Imaging Radar SIR-C illustrate the potential benefits of dual polarized observations from Envisat for the discrimination of ice types. The possible value of active-microwave observations at Ku band and passive-microwave observations from the SSM/I is also discussed.

Space borne Ku-band pencil beam QuikScat-SeaWinds scatterometer dat over sea ice in Greenland waters are analyzed with the aid of co-located: 1) sea ice charts issued by the Greenland ice service 2) DMSP-SSM/I passive microwave data and 3) HIRLAM numerical weather model analysis data. Seasonal variations in backscatter signature between different sea ice types are analyzed. Ice parameters such as ice concentration and ice type are significant for the backscatter signature;. The role of wind roughening of open water areas in low concentration ice cover, which can easily be seen in SAR imagery, has ben investigated using a Ku-band wind-backscatter model and ice charts. It is found that in areas with low concentration ice cover there is still a strong correlation between the backscatter coefficient and the wind speed. Except for the cases of surface melt the variations in (sigma) ₀ of multi-year ice, north of Greenland are small. For first-year ice in Baffin Bay the variations in (sigma) ₀ are larger than for multi-year ice. Further the variations in air temperature shows a significant correlation to the variations in (sigma) ₀. Both the (sigma) ₀ of multi-year ice and first-year ice change dramatically at the onset of ice surface melt. Multi-year ice decease by approximately 7 dB and first-year ice increases by approximately 5 dB. The fine scale structure and composition of the ice cover can be resolved using Radarsat ScanSAR imagery. Cases of coincident Radarsat and QuikScat data are compared in connection with the first-year ice development in Baffin Bay. A mean backscatter signature is defined. Finally the results from this investigation are used for ice type classification.

The ocean response to pressure variations is subtracted from altimeter records using the standard Inverse Barometer Correction (IBC), based on the hypothetical isostatic assumption. Previous analyses have demonstrated that this assumption has to be applied with care when the high frequency pressure variations are considered, as is the case of using the crossover track method. Using ERS-2 radar altimeter data, we study the response of the Atlantic Sea Level (ASL) to pressure forcings at different ranges of frequency, in order to determine the validity of the isostatic assumption. We have also determined this response when using the outputs of a Global Ocean Model (GOM) forced by pressure and wind fields. From the comparison between both results we have observed that data errors could be underestimating our estimations of the response of the ocean to pressure variations; this underestimation could represent more than 20 percent of the values obtained in equatorial and tropical zones, being insignificant out of the latitudinal band.

The Altimetry mission on EnviSat will extend the time series of observations started by ERS-1. The new features of the RA2 mission will improve the quality of the measurements in many aspects. The new on-board algorithms for tracking the surface, the larger range window and the extra low resolution mode will all improve data acquisition over the important ice sheet margins and over most land and wetland surfaces. New, in-situ ionospheric corrections from the dual radar frequency will be a significant improvement on the model-based corrections used in previous missions. The more precise DORIS orbit will improve the precision of all measurements, particularly in near real time. The near real time products will be built with the same algorithms than the off-line final precision products, only some auxiliary input data may differ, thus providing already in 3 hours near-high quality Geophysical Data Record Products to support near real time Oceanography.

Demand for near-real-time satellite ocean observations is rapidly increasing with the development of operational oceanography and its applications such as ocean monitoring for offshore oil exploitation, fish resources management or detection of surface pollution. Ocean color is one of the few important ocean properties measurable from space. Vegetation, launched on-board SPOT-4 in 1998, is a push- broom sensor equipped with 4 wide field-of-view cameras corresponding to 4 spectral bands: blue, red, near-IR and SWIR bands. Unlike SeaWiFS or MODIS, vegetation was not designed for ocean color studies. Nevertheless, we demonstrate here that useful ocean color measurements can be deduced from the vegetation blue band, the only that is significantly sensitive to the marine reflectance. The main processing steps include: i/correction for gaseous absorption, ii/correction for molecular scattering which represent, for the blue band up to 90 percent of the total observed radiance, and iii/correction for aerosol scattering. Vegetation system being fully operational, near- real-time ocean color observations can thus be obtained with this instrument. The first results, concerning a limited ocean region, are presented and compared with SeaWiFS and radar altimeter observations.

Traditional approaches to remote sensing of coral reefs have been highly empirical, relying on classification of remote sensing images. We have chosen a physics based approach - the collection of reflectance spectra of different substrates and the determination of the inherent optical properties of the water column. This information, together with radiative transfer models of water and atmosphere as well as technical characteristics of different remote sensing sensors, allows us to estimate what benthic communities are spectrally resolvable with respect to water column depth and the sensor characteristics. A hyperspectral library of more than 140 different coral reefs substrates (living hard and soft corals, dead corals, rubble, sand, algae and sponges) were collected from the Great Barrier Reef. Hydrolight 4.1 model was used to simulate remote sensing reflectances above the water and a MODTRAN3 type in-house atmosphere model was used to simulate radiance at airborne and space borne sensor levels. Most of the spectral variability in reflectance of coral reef benthic communities occurs in the spectral range of 550-680 nm (green to red light). The water itself is a main limiting factor in remote detection of various reef substrates, as water itself is absorbing light strongly in the same part of the spectrum where most of the variability in reflectance spectra of different coral reef benthic substrates occurs. Hyperspectral information allows us to separate different substrates from each other more easily and in deeper waters than broad band sensors.

The selected study area is the Strait of Penang, located in the north western part of peninsula Malaysia. Satellite imagery is employed as an aid to bathymetric charting. The depth sounding points retrieved from published bathymetric chart are used for calibration. Cloud free scene of ADEOS AVNIR data acquired on 14 January 1997 was available for use in the present study. This scene was rectified to the corresponding bathymetric chart. Image locations were related to the chart coordinates through the second degree polynomial transformation equations. Multiband water depth algorithm was used in the calibration analysis. Regression technique was used for calibration of the satellite signals for water depth recorded in the bathymetric map of the selected locations. The correlation coefficient and root- mean-square deviations were examined. The accuracy of calibrated algorithm was further verified using other known sounding points. The calibrated algorithm was then applied to the corresponding image to generate a water depth map. The color coded bathymetric map was used for visual interpretation and assessment of the present water depth pattern.

This paper describes an analytical 2 flow equations solution and compares it to a Monte Caro model of the photon flux in water. Both models are designed to generate synthetic water surface reflectance signatures as well as the vertical profiles of light in a homogeneous or non-homogeneous water column of specified depth and bottom reflectance. In this paper we compare and contrast the results of the models and develop a theoretically based attenuation function of both models. The results from the Monte Carlo model are used to compare a form of a 2nd order attenuation term (Psi) , resulting from a solution of the 2-flow equation, to 3 downwelling irradiance dependent terms. The results show that (Psi) differs from the three terms by 1 to 14 percent depending on the scattering to absorption ratio and volume scattering function. The result also show that (Psi) is dependent on the shape factor.

Remotely sensed surface data over the ocean constitute an independent and quasi-synoptic source with which in situ estimates, such as ship, buoy and coastal/island station data or marine-atmospheric modeling outputs can be complemented and compared. We focus on the Mediterranean Sea, where all the water masses are formed at the surface via recurring extreme air-sea interaction events, thereby rendering necessary the monitoring of the air-sea interaction parameters for the understanding of the variability in the characteristics of the water mass characteristics and circulation. The combined use of passive microwave (SSM/I) and thermal (AVHRR) satellite data has permitted to develop algorithms to obtain specific humidity q, air temperature Ta and wind intensity U. We obtained these from the literature and applied them to the Mediterranean SSM/I data, with the final scope of monitoring its energy and water budgets. The present preliminary validation effort is made against the meteorological data relative to a number of oceanographic cruises carried out on board R/V Urania of the Italian National Research Council (CNR), a data set coming from a moored buoy managed by the Istituto di Automazione Navale (IAN-CNR) and the ECMWF and MIAO model results.

In the framework of the current development of offshore wind energy exploitation, an accurate evaluation of the wind potential is crucial for sitting windmills. Nowadays, the resource is evaluated by intrusive means that provide discrete measurements. These measurements must be extrapolated in order to provide a global wind resource map. But in this case, local conditions and variations of wind are not expressed. This paper deals with a methodology developed to provide accurate offshore wind potential statistics. Firstly, the method developed to obtain accurate wind maps from ERS SAR (Synthetic Aperture Radar) images is presented. Then, considering the need of dense statistical information for evaluating the wind potential, a data fusion methodology is exposed.

In this paper a study regarding the role of the objective function used in the wind field reconstruction procedure from normalized radar cross section measurements achieved by means of a microwave scatterometer is detailed. The relevance of the study has practical interests since the capability to best estimate the sea surface wind field from satellite measurements is going to affect the climatological models and weather forecast models once that the full deployment of such powerful remote sensing tools will ensure a sufficient temporal and spatial coverage. The results hereafter shown suggest as the best objective function the WLSL one.

In the microwave domain, the development of interaction models has proved itself necessary for the understanding of the interaction between the electromagnetic wave and the sea surface and for the efficient retrieval of surface parameters from spaceborne measurements, such as in altimetry and wind scatterometry. New potential applications of microwaves over oceans involve frequencies such as L-band (around 1.5 GHz), both for active (such as the use of reflected GNSS signals for scatterometry and altimetry) and passive (extraction of ocean salinity from radiometric products) measurements. Classical models, mostly developed for higher frequencies and for close-to-nadir geometry's, may show limitations when applied to these new configurations. Another important issue is the sea surface description, which may need to be somehow refined to enable a complete picture of the interaction mechanisms at these wavelengths. L-band measurements of the sea surface (concurrent to local measurements of the sea state) are still quite scarce and this makes difficult the validation of modeling tools. It is however possible to use a well controlled full-wave approach, such as the moment method, as a reference to evaluate the assets and drawbacks of simpler asymptotic models (Physical Optics, two-scale model, etc .). The objective of this exercise is to exhibit a parameterization of the simpler models efficient enough to ensure an adequate restitution of the main scattering/emission mechanisms. Studies are conducted for different sea conditions. The wave-surface interaction mechanisms expected to drive the signal are studied for different configurations of observation. Then, the preliminary consequences in terms of interaction model accuracy at these wavelengths are pointed out.

A new concept for altimeter signal processing is described and a radar method is developed, for the determination of sea surface wind speed and the different of near surface air and water temperatures, from combined amplitude and phase characteristics of the altimeter signal reflected form the sea surface.

We analyze thermal satellite images relative to years 1997, 1998, 1999, 2000 to infer cold filament and surface jets in the Mediterranean Sea. The main zones to see these SST phenomena are characterized by strong cold winds funneled by somewhat irregular coastal topography. In the coastal zones, indeed, the strong air-sea interaction generates a particularly strong input of potential vorticity, that can give origin to upwellings, cold filament and jets. So the geographical zone more 'rich' of these narrow or large jets, are the tow lobes of the Southern Sicilian coast, the sea off Olbia in Sardinia, that South of the Island of Crete where a particularly intriguing large scale turbulence is evident, and the Balcanic coast of the Adriatic sea. Of particular interest is the analysis of these jets and their evolution using a modern version of the potential vorticity conservation, valid even if friction and entrainment are large.

In this note the winter presence of a tongue of cold water turning around the Apulia Peninsula, in Southern Adriatic Sea, is analyzed. Autumn and winter satellite thermal images indeed show that often cold water masses occupying the western part of the Strait of Otranto, where the bottom depth is about 800m, tend to flow clockwise apparently following the isobaths around Cape S. Maria di Leuca and finally intrude into the Gulf of Taranto. These images are here compared with CTD casts and current meter observations made during the same period, and also with some drifter surface measurements. A deepening of the surface current, and its peculiar locking into a current of Mediterranean Dense Water flowing geo strophically over the sea bottom, is also discussed as a kind of barotropic reconstruction for these clearly baroclinic flows. Theoretical considerations allow to gain some insight into these currents and their potential vorticity evolution.

Recently there has been considerable interest in the problems of optical imaging in turbid, strongly scattering media, such as tumours in biological tissues, objects in water, etc. To detect objects in the media the analysis of backscattering of picosecond signal can be used. In this paper we report about the influence of medium parameters and detector parameters on temporal profile of the reflected pulse and its intensity. Virtual experiments were carried out with the MONTE-CARLO method, and temporal profile of signal was obtained. The dependencies of the forepart and tail-part of the signal fronts, maximum position of the reflected signal and the reflection coefficient from the scattering particle density and cross section were obtained. These dependencies show that the tail-part of the signal is greatly decreased while the density is increased, compared to the forepart and maximum intensity position of the signal. These results can be used to analyze the scattering particle density and cross section in the turbid materials. Virtual experiments with the presence of various inhomogeneities were performed, which show that not only reflecting and absorbing solid objects, but also even density inhomogeneities can be detected.

Teleoperation provides a means for in-situ continuous observation of, and interaction with, remote sites that are difficult and potentially hazardous to access directly. The Hudson submarine canyon, with its proximity to a large population center is an ideal test bed for an on-going teleoperation approach to its exploration and observation. To facilitate a long duration mission and freedom from an expensive and weather dependent surface support ship, an underwater electrical recharge site is proposed. A power line/fiber optic cable is placed from shoreline facilities to the recharge site, located on the upper rim of the canyon at approximately 100 meter depth. Here, free flying remotely piloted vehicles periodically recharge batteries and send video/data back to the surface. The entire venture is located underwater and remains there for the duration of the mission. The recharge site can be relocated to expand the exploration area. Various alternate canyon sites worldwide are considered. Internet access, and an access fee structure for the general public, presents the possibility of an economically self-supporting venture when conducted on a sufficiently large scale.

In this paper we conduct sensitivity analyses of the land surface boundary conditions and parameterizations in the UTC-M primitive equation atmospheric planetary boundary layer Seabreeze model. The boundary conditions for temperature of the ocean and land surface is based upon satellite derived AVHRR estimates over the water and coastal land margins. The sensitivity analysis of the boundary conditions as well as the heating and cooling rates in the planetary boundary layer model are also described. The model domain of interest is the region over the Space Coats of Central Florida. This reign is unique because of its complex coastal water-land margin and its close proximity to the Gulf Stream and Cape Canaveral. This model study demonstrates a method whereby the ocean surface and atmosphere is couple using remotely sensed data for predicting the coastal Seabreeze and associated convective convergence and expected cloud development in the planetary boundary layer.

The aim of this study is to find the algorithms for estimating the biomass of the Emiliania huxleyi from the irradiance data of the sea water surface. For this purpose, the relationships between the biomass of the Emiliania huxleyi in an axenic tank culture and the water irradiance data measured by a spectroradiameter were found. During the growing phase and stationary phase of the Emiliania huxleyi, the total attenuation, absorption and back scattering coefficients of the water in the tank were calculated from the irradiance data. The ratio of the water irradiance data at 670nm and 814nm were well correlated with the total cell concentration of the Emiliania huxleyi. It is expected to help for the biomass estimation of natural blooms in the ocean.

The development of high frequencies theory and practice of radiometric sensing of environment has shown an opportunity to receive the information on temperature and salinity of superficial water layer, underwater wind speed, on which depends geometry of a surface and share of its covering foamed formation. The further development of satellite microwave measurement needs to find a solution to the problem of great multiparametrical return tasks. In this paper we consider regression and electrodynamic model of the sea and ocean and their limiting errors of electro physical parameters measurements of sea surface in order to find the solution to the tasks. The measurements are investigated at passive remote sensing. Temperature and concentration dependence of complex dielectric permeability of water and water mono and polyelectrolyte systems are also investigated. The measurements are executed with the help of the developed experimental stand of a reflective type on frequency 35.5 GHz at the interval of temperatures 271-353 K. Radiobrilliance temperature for regression and electrodynamic models of the sea and ocean, are designed with the help of received date.

This paper compares homogeneous analytical two-flow equation solutions to an improved iterative solution technique of the same differential equations that describe the transfer of irradiance in a layered medium such as water with depth dependent water constituents. The layered model is developed to be used in oceanic or atmospheric models in order to provide a detailed mechanism for the influence of irradiant energy in the heating rate of the medium. The layered model is designed to generate synthetic water surface reflectance signatures in the presence of depth dependent water constituents, various bottom types, and variable water depths. In addition, the model allows one to compute the influences of submerged targets or layers with unique reflectance signatures or unique absorption and backscatter characteristics.