Until recently, the Aswa lineament shear zone in Uganda and Sudan was considered to be tectonically at rest but the 1990- 1991 seismic events triggered a renewal of interest in this area. Using ERS1 - ERS2 tandem covering the area where earthquakes were observed, we have generated a high resolution Digital Elevation Model (DEM) which provides a good quality reference to analyze the geomorphology and the drainage patterns, in order to extract valuable tectonic information. Then, the combination of spaceborne radar interferometry and Landsat TM imagery contributes to a better understanding of the geological and tectonic phenomena of the studied area.

This paper reports on the first lidar imaging experiments carried out on a historical monument. The measurements were carried out by scanning the northern facade of the Lund cathedral from a distance of at least 60 m with a mobile fluorescence lidar. Two different arrangements were used for the receiver: an optical multi-spectral analyzer or two photomultipliers equipped with interference filters. Depending on the wavelength the fluorescence images allow the mapping of biodirection colonization or of the different stony materials. To our knowledge these were the first images of a historical building detected by a fluorescence lidar.

The legendary 'Ciudad Blanca' of Honduras was first referred to under the name Xucutaco by the Spanish conquistador Hernan Cortes already in 1526. Located in the remote, impenetrable and incompletely mapped rainforest of the Mosquito Coast, it was never conquered by the Spanish. With the time, it was slowly abandoned and forgotten. Two JERS-1 and one ERS-2 SLC Synthetic Aperture Radar (SAR) images have been used to identify and to locate the lost city, a task made difficult due to the thick vegetation cover. To this end, advanced processing tools for the detection of artificial targets under forest cover, and for SAR data fusion have been used. Among the techniques used, a new Bayesian Distribution Entropy Maximum A Posteriori (DE-MAP) vector speckle filter, particularly suited for the restoration of a strongly textured scene, has been used to enhance the SAR images. This new speckle filter incorporates a statistical description of the effects of the SAR imaging system: in order to account for the effects due to the spatial correlation of the speckle in SAR images, an estimator originating from the local spatial autocorrelation function (ACF) of the SAR signal are incorporated to this filter, to refine the evaluation of the non-stationary first order local statistics, to improve the restoration of the scene textural properties, and to preserve the useful spatial resolution in the speckle filtered image. On the other hand, radargrammetric techniques have been used to: (1) produce a Digital Elevation Model (DEM) of the study area; (2) fuse ERS and JERS information in order to allow visual identification of the remnants of Ciudad Blanca by visual photo-interpretation. Using the processed images, geocoded UTM spatio-maps of the region have also been produced to locate accurately our findings, and guide a ground expedition in the future.

The main aim of this work, carried out in the framework of the PRISMA2 national research program (Research and Experimentation Program for the Adriatic Sea) was the definition of an appropriate working methodology which allowed to estimate the impact of the Esino drainage-basin (central Italy), and of the anthropic activities lying on it, on the coastal water quality of the Adriatic sea. This aim was pursued by integrating techniques and instruments of analyses, such as GIS and remote sensing, which are often and often employed in natural resources managing and planning. They allowed to generate a database easily updating, relative to a very large area which is strongly differentiated in its natural and anthropic features. The database contains raw data, provided by local public organizations managing the territory, information derived from elaboration of the previous data and remote sensed frames (acquired by the hyperspectral sensor MIVIS) purposely acquired to the aim of the study. It was after all generated an 'open' system, continually updating with environmental information before long available; moreover, were explored the potentialities of the MIVIS sensor (102 band, from the visible to the thermic IR) in the study of marine coastal water quality.

In order to diminish the degree of flood hazard, it is necessary to acquire more geological information, particularly about the predisposing causes. As known, the exogen changes and their control are linked with the regional tectonic structures, hence it is important to identify them. Indeed, the reconstruction of a geomechanical-fracturing model of the rock substratum can be the main element to localize the lowering plane areas that probably draw the flood. For this purpose, the RS-multispectral satellite image interpretation becomes the more suitable method. It was applied over a test area SE of Turin (Piedmont, NorthWest Italy) where localized floods systematically occurred. The identified tectonic model shows that the lowering structural areas correspond also to the flooded depressions.

In this study were evaluated the utility of ERS-1 satellite imagery in conjunction with ancillary data for mapping the flooded areas of the November 1994 flood event occurred in Northern Italy. Two images were analyzed, one collected a month before the flood and the other one collected three day after the inundation. Two processing procedures and a visual interpretation were applied within a masked area extracted from the digital elevation model (DEM). Areal extent of flooded surfaces retrieved by the different methods were compared with the actual flood extension derived from field survey. Intermediate results showed that only a small fraction of the total inundated area was possible to estimated because of the time shift between flood and satellite passage. To overcome this limitation a procedure based on the integration of flooded areas as previously estimated by radar images, with a cost matrix calculated on the basis of the DEM was developed in a Geographical Information System (GIS) environment. This method allowed to map additional inundated areas amounting 96.7% of the actual flooded area. Result shows that even if radar data are taken some days after the inundation, they are still well suited to reconstruct flooded area when DEM is employed in the mapping process.

One of the 22 active volcanoes in the Philippines is Mt. Bulusan. The volcano erupted more than 15 times recent history, but the majority of these eruptions were mild phreatic eruptions. Field evidence shows however that Bulusan is capable of producing lava flows, domes, pyroclastic currents and lahars. Bulusan therefore poses a potentially major risk to the dense population at the footslopes of the volcano. Hence the volcano is constantly monitored with seismic equipment. To mitigate the potential hazards posed by this volcano, a volcanic hazard mapping program has been undertaken. Because of lacking existing geological and geographical data, it was decided to use optical and radar remote sensing techniques to acquire additional data. A GIS database was created at a medium scale, which was used as a reference for the development of preliminary hazard maps for each of the volcanic hazards that have been identified. An elementary approach, making use of the 'Energy cone' concept, was followed to outline the areas subject to potential pyroclastic flows and surges. Lava- and lahar flow path predictions were made based on the Digital Terrain Model (DTM).

Radiometrically-calibrated Landsat TM data are combined with conventional observations (soil and geology maps, hydrogeological data) to analyze change in the land cover of the Los Monegros region of Aragon, Spain, over the period 1984 - 1997 in order to evaluate the effects of the extension of irrigation on the extent of arable agriculture. Linear spectral unmixing combined with a band ratio mask is used to determine proportions of individual soil types. A change detection technique based on principal component analysis is used in order to identify areas that are most at risk from land degradation processes, principally increased soil erosion and soil salinization, and to explain the ways in which agricultural practices interact with the geomorphological and hydrogeological characteristics of the study are in inducing and maintaining the processes driving change.

In this study a relationship between water surface area and river discharge was derived by using multitemporal radar images in the central braided part of the Ticino River (Italy). Ticino River is the outlet of the Lake Maggiore (north-west Italy) and it streams for about 100 km before flowing into the Po River, the biggest river in Italy. The braided part of Ticino River is about 50% of the total length and its active flow increases or decreases in responding to river discharge. Ground measurement of discharge (Q) were related to satellite-derived effective width (We), where We is the water surface area within a braided reach divided by the reach length, showing a good correlation. Power functions were fitted through plots of We and Q and they represent satellite derived rating curves that can be helpful for the estimation of mean daily discharge by using satellite radar data. Those satellite-derived rating curves can be apply where the gauging station are either enough distributed, like in Ticino River, or impossible to set in order to predict the river discharge or in remote areas, where river discharge is not easily available.

In this study daily spatially distributed evapotranspiration maps were estimated by integrating meteorological data-set, ground measurements, satellite images and Digital Elevation Model in a Geographic Information System environment to resolve latent heat flux as residual term of the one- dimensional surface energy balance equation. Study area was the Masino catchment located in northern alpine environment (SO, Italy), mainly dominated by forest land cover and characterized by steep slopes, variable aspects, cast shadows and great relief energy. A digital elevation model with pixel size of 25 X 25 m, was necessary to correct the Landsat TM scenes for the relief displacement using an orthorectification model and to correct the atmospherically effects using an improved image-based inversion algorithm based on a radiative transfer model. The procedure for estimating energy balance components was based on the evaluation of the energy balance equation distributing each component on the whole catchment. A simplified procedure was applied to relate instantaneous latent heat flux to actual daily evapotranspiration and the results were compared with that computed in correspondence to the meteorological station.

Most of the approaches for urban characterization in the remote sensing domain, are based only on the use of spectral information, not taking into account the geometric characteristics given by the spatial distribution of urban elements. An urban area can be spatially described on the basis of the distribution of urban elements such as buildings, roads, green areas. The analysis of these local properties may enrich the spectral information, improving the differentiability among suburban areas originally belonging to homogeneous areas. On this basis the analysis of different texture of urban areas was introduced. It is based on the study of the spatial distribution of gray level variations. In this work a window and orientation independent approach is presented, based on the detection of regions (or objects) surrounded by elements of separation. This method is performed using the analysis of connected regions. Texture features are calculated within the detected regions to group regions with the same geometric structure. The data set used in this study is formed by panchromatic SPOT satellite images, that highlight urban texture. In order to validate the approach, this method has been applied on Como, Catania, Pavia and Piacenza (Italy), representative samples of different urban typologies.

Many algorithms and data analysis techniques have been proposed up to now which make use of satellite observations within atmospheric widows mainly for clouds and surface parameters studies and for environmental monitoring applications. Quite all these algorithms are difficult to extend to different geographical, seasonal conditions, having generally poor performances and uncertain reliability especially when applied in environmental risk prevision, monitoring and/or mitigation. In this paper a new, robust (in a statistical sense), approach (RAT) to the use of NOAA/AVHRR observations is proposed and its successful application to different environmental emergencies illustrated also in expectation of next generation of satellite sounders devoted or usable for environmental monitoring purposes.

OGCM's numerical experiments for climatic studies can be performed only after testing their capability to well represent the today ocean circulation. In order to improve the model results we assimilated satellite SST (from NOAA-AVHRR sensors) by means of a nudging method. Daily 1987 - 1992 NASA Pathfinder SST have been interpolated in time and space by means of an objective analysis algorithm to fill gaps in the time series. These data were analyzed to investigate the main variability of the Mediterranean SST field. The 1988 data was selected to be assimilated in the OGCM. To relate more closely the assimilation of the SST data to the physics of the air-sea interaction, here we propose a new parameterization of the surface relaxation time. Actually the use of realistic surface forcing strongly contribute to reproduce the correct hydrological values of the Mediterranean water masses, the right energetic basin budgets and the mesoscale features of the Mediterranean circulation.

The objective of the study is to develop an algorithm of the bottom index for monitoring and sureying coral reels using the aerial multispectral imageries collected by the Compact Airborne Spectrographic Imager (casi) which spectral and spatial resolution are very high. Four kinds of bottom indices such as the bottom index, the brightness index, the bottom type index and the band ratio index were applied to the casi data to extract coral reefs at the off Kuroshima Island, Okinawa. To select the most suitable wavelength range for extracting coral reef area from the casi imageries, all combinations of the spectral bards were applied to each index. The selected spectral bands for the four bottom indices were the combination of two bands, band 39 (700 nm) and band 36 (680 nm), band 39 (700 nm) and band 27 (610 nm), band 39 (700 nm) and band 13 (500 nm), band 13 (500 nm) and band 27 (610 nm), and band 27 (610 nm) and band 24 (587 nm). For the bottom index, the combination of the band 39 (700 nm) and band 36 (680 nm) showed the most significant similarities with the ground truth survey by the professional divers.

Upper ocean dynamics is characterized by a strong variability, at different scales, both in direction and structure of the flow. Mesoscale variability, which is ubiquitous in the world ocean, is often the dominant component in the variance spectrum of velocity with relevant implications on water mass mixing and transformation and on the carbon transfer in the marine food web. Mesoscale activity is manifested through the formation of instabilities, meanders and eddies. Eddies generate either a doming of isopycnals (cyclones) or a central depression (anticyclones). This in turn modifies, among the others, nutrient and organism distributions in the photic zone eventually enhancing or depressing photosynthetic activity and other connected biological responses. The mechanism is similar to what has been thoroughly studied for the warm and cold core rings but at different spatial and temporal scales. The enhancement of phytoplankton growth and the modification of photosynthetic parameters has been shown to occur in situ by means of a modulated fluorescence probe. More recently, an attempt to estimate the magnitude of this specific forcing on nutrient fluxes and primary production has also been conducted at different scales by modeling exercises, though with contrasting estimates the relative importance concerns. Because phytoplankton growth takes place when light, nutrients and cells are found at the same place, the increase in primary production favored by mesoscale eddies cannot be easily predicted. The incident light, the seasonality, the life-time of the structure, its intensity etc. can all influence the final yield. In addition, it has still to be determined which component of the community reacts faster and takes advantage of the new nutrients and how efficiently the new carbon is channeled in the food web. For what remote sensing is concerned, the detectability form the space of such structures is certainly dependent on the depth at which the upward distortion of isopycnals takes places. It can be supposed that a change in bio-optical signature of the whole structure could occur because of the 3-D dynamics of the eddy. If this holds true, then color remote sensing coupled with sea level topography and sea surface temperature should be a powerful tool to track such transient structures. The ALT-SYMPLEX program has been designed to better understand the relationship between short living eddies and carbon transfer in the food web. This is based on several experiments aimed to integrate remote sensing data (ocean color and surface topography) and in situ data in order to evaluate the relationship between surface and sub-surface physical dynamics and its relations on chemical and biological aspects in presence of mesoscale features.

The analysis performed in this paper is based on only two fully polarimetric airborne C- and L-band SAR images acquired over the Baltic Sea. The polarimetric discriminants computed from these two scenes are compared shortly with the corresponding results obtained in the Arctic conditions. Then the properties of the polarimetric discriminants as sea ice type classifiers are investigated. The backscatter coefficients with one polarization act as reference discriminants. The comparison between these two classifier sets is carried out with coarse resolution data.

The PRISMA is a research project, sponsored by the Italian Ministry for University and Scientific Research, devoted to the study of the Adriatic Sea. Within this project, the general goal of the IROE has been the development of a measurement procedure for the detection of marine fronts which integrates the NOAA-AVHRR imagery and the fluorescence lidar data. The paper reports the activity performed during the different measurement campaigns and discusses the results obtained during the first winter campaign carried out in February 1997. A good agreement was found between the front position as detected on the AVHRR thermal images and the position detected by the fluorescence lidar on the base of the change in chlorophyll and DOM concentration as well as in the change of the water Raman signal.

Satellite remote sensing of sea color is a powerful instrument to perform oceanic studies. Unfortunately, the present data processing algorithms are not exempt from uncertainties, especially because the marine radiance must be separated from the atmospheric contributions, which typically represent about 80% of the total. In this paper we suggest the development of observation methods based on the optical radar or lidar. In fact, the numerical simulation of a sea-level optical radar demonstrates that, if applied to restricted areas, such system is a precise and versatile tool for the atmospheric correction of marine radiance data sensed from satellite (accuracy better than 10% for typical conditions). Moreover, the lidar is effective even in environments that would be severe for the standard corrective schemes. Finally, the feasibility of a spaceborne system is discussed.

The difficulty of the remote sensing of coastal water is the presence of more than one constituent with high variability ranges, different correlation and spectral behavior. They are superimposing in their influence on the resulting total spectrum. Simple ratio algorithms applied to remote sensing data fail on the quantitative determination of the single constituents. However, coastal regions are of great interest for remote sensing since most of the consequences of urbanization are manifested here. For the improvement of remote sensing of coastal zones it is not only necessary to build a new generation of sensors that offer spectrally higher resolved data, but one has to develop a new methodology that allows the separation and determination of the water constituents based on the entire spectral signature of the different components of the water body. The imaging spectrometer MOS flying on the Indian remote sensing satellite IRS-P3 provides since March 1996 remote sensing data in 13 spectral channels for the scientific community. We implemented a new methodological approach to derive different case II water constituents as well as atmospheric turbidity for the application of MOS-data in costal regions. A new point of the method is the uniform consideration of atmospheric and water constituent influences on the remote sensing signal. The paper will present a short overview on the algorithm's essentials and examples for the large variability of coastal waters around Europe basing on the results of the retrieved water constituents using the MOS algorithm. It will demonstrate the promising potential of this new algorithm for discrimination of single constituents under case II conditions. Derived maps of chlorophyll like pigments, sediments and aerosol optical thickness are shown and will be discussed.

Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Florida. Stations were also occupied in near coastal waters out to the edge of the Gulf Stream in the vicinity of Kennedy Space Center, Florida and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting optical cross section signatures suggest different models are needed for the different water types and that the common linear model may only appropriate for coastal and oceanic water types. Mean particle size estimates based on the optical cross section, suggest as expected, that particle size of oceanic particles are smaller than more turbid water types. The data discussed and presented are necessary for remote sensing applications of sensors as well as for development and inversion of remote sensing algorithms.

The simulation of radar altimeter echoes is a fundamental tool to set up an accurate ground processor for estimating ocean parameters. This paper arises from a thesis work based on the simulation approach proposed by Tateiba and Fujita. It is based on the specular point approximation of the electromagnetic scattering problem but in principle it does not require assumptions on the properties of the random surface and the transmitted signal. The more critical aspect of the proposed solution is the identification of the specular points within the area illuminated by the antenna that requires to impose the orthogonality among a generic optical ray emerging from the antenna and the local plane tangent to the surface. In this paper, we have reconsidered the mentioned approach. In particular, we have refined the method to search the specular points in order to improve its efficiency. We have tested the implementation of the algorithm for an isotropic Gaussian surface and compared the results to the waveforms derived by using the 'Brown model'. We have also retracked the simulated waveforms using a processing software developed by Telespazio S.p.A as a first attempt to use the simulator within an accurate processing chain for altimeter data. Moreover we have compared the statistics of the echo to what is expected from a completely developed speckle.

A coupling of field and satellite remote sensing data were used to improve the knowledge with respect to coastal dynamics and erosion process as well as on the importance of mangroves as a mechanism of fertilization of tropical NE-Brazilian waters. RADARSAT and ERS SAR images were used to position morphologic features, to trace coastline evolution and detect changes in mangrove coverage. Analysis of aerial photography, ERS and RADARSAT images, reveal that mangrove areas have been drastically reduced in the last decades, to give places to new urban settling. Coastal erosion appears to have been intensified after the installation of harbor facilities and by the construction of beach houses and other structures along the shore, that modify coastal circulation and nearshore sediment transport. Particular importance is given to the analysis of the RADARSAT SAR image taken in September 1997.

Due to the increased covering from satellites it is possible to find several sensors offering spatial information of the oceanic surface features as images obtained through different sensors such as visible, intensity, color infrared or microwaves (S.A.R.) (from satellites such as METEOSAT, NOAA, TOPEX, LANDSAT, ERS1 and ERS2). We use data from the altimeter and the SAR images from the ERS-1 as well as images from ERS- 2. SAR images and their analysis with flow visualization techniques uses correlations from SAR intensity that allow the calculation of maps of the spatial variation of integral scales. The integral scales which seem dominant, range between 15 and 20 Km showing a limit at the Rossby deformation radius. These larger lengths may be explained as micro and mesoscale vortex interaction in the surface of the ocean. They might also be related to barometric corrections caused by the mirror images produced by the atmospheric pressure on the atmosphere, but checking the weather maps at the same time confirms that atmospheric relevant lengthscales are much larger as a consequence of the larger Rossby deformation radius for atmospheric flows.

The total attenuation coefficient is a significant parameter of the water column being strictly related to the light penetration depth and to the quantity of suspended and dissolved substances. This parameter is measured in situ by optical instruments while its remote measurement can be achieved by lidars. The lidar measurement of the total attenuation coefficient is based on the Raman scattering due to the OH stretching of water molecule. This paper discusses the analytical base of the measurement.

We study the link between bottom topography and its expression on a free-surface using Large-Eddy Simulations (LES) on the laboratory-scale. Free-surface patterns are presented for three configurations: neutral flow over wavy topography, stratified flow over wavy topography, and neutral flow over three-dimensional sinusoidal topography. The extent to which each configuration produces unique and identifiable surface patterns is explored. Our focus is on the fluid mechanics near the surface, for example, attachment and persistence of vortical structures, upwelling, and zones of convergence. Neutral flow over wavy topography creates a large number of powerful upwellings on the free surface. These upwellings appear to overwhelm the coherency of pre-existing vortices and vortex pairs. Consequently, the persistence of organized vortical motions on the free surface is reduced. In contrast, in stably stratified flow over a wavy boundary, upwellings are weakened, and more vortex pairs are observed. The surface signature of three-dimensional underwater topography shows elongated streaks in the streamwise direction. The above features allow these underwater topographies (at the depths presented) to be uniquely differentiated based solely on their surface signatures.