Linear spectral mixture models (SMM) with image endmembers (IEM) and with reference endmembers (REM) were tested for discriminating maritime pine stands and shrublands in a Landsat-TM image of Central Portugal. For both types of EM, IEM and REM, two types of SMM were tried: SMM with three EM (SMM-3), i.e., green vegetation, soil and shade, and SMM with five EM (SMM-5), where the EM were the components of the landscapes that we were interested on, i.e., pine canopy, shrub, soil, forest litter and shade. Results showed that in the SMM-5, REM need to be used, since IEM were not pure enough. We verified that in the SMM-5, there was not a single set of EM that could be applied to the whole study area, because the shrubs that exist underneath the pine canopy and in the shrublands could not be modeled just by using a shrub EM. Therefore, SMM-5 require a multi-endmember approach, where the set of EM may change from pixel to pixel. In the SMM-3, an accurate discrimination of shrublands and pine stands (90% accuracy) was achieved by thresholding the shade fraction. In these simpler SMM, IEM and REM produced similar results.

The SAIL model was used to simulate integrated (overstory/background) hyperspectral reflectance of maritime pine stands. We simulated the spectral reflectance of pine forests with different pine canopy Leaf Area Index (LAI) and with different types of vegetative and non-vegetative backgrounds. As vegetative backgrounds we used data collected on plots established over open air shrublands and that are representative, in species composition and in biomass, of the understory of the maritime pine stands in Central Portugal. As non-vegetative backgrounds we used pine needle litter, soils and pine slash, which reflectance was measured over optical dense piles of the pure materials. Results indicate that the contribution of the background cannot be neglected on the accurate estimate of pine canopy LAI in regional areas characterized by a large spatial heterogeneity of backgrounds. Results also suggest that, if one knows the pine canopy LAI, the background of maritime pine stands can be characterized for almost the whole pine canopy LAI range of maritime pine stands in Central Portugal. At the end, we present some considerations on new techniques for the exploration of remotely sensed data for the structural characterization of the overstory and background of maritime pine forests.

Western Burkina-Faso is a pole of intense population migration that conducts to problems of space saturation and land degradation. The present study deals with the natural vegetation characterization of this region using the high resolution visible and infrared (HRVIR) sensor that will be launched on SPOT 4. We adopted a theoretical approach which consists in evaluating the capacity of the future short wavelength infrared (SWIR) band to discriminate natural vegetation types using a 3D radiative transfer model (Myneni's model). Simulations were conducted with realistic input parameters (different vegetation structure, soil, satellite, atmospheric conditions . . .) during dry and rainy seasons. The outputs of the simulations (bi-directional reflectances, vegetation indices) were used to study the sensitivity of the SWIR to vegetation type and to external conditions. The results show that the SWIR band is well correlated with the red channel during the wet season, and with the near infrared (NIR) and red channels during the dry season. Its sensitivity to the atmosphere is low, and the sensitivity to the soil type is medium. The sensitivity to the woody cover is high during the dry season (about 1.6 points of reflectance per 10% of woody cover) but is still equivalent to the NIR sensitivity. Spectral vegetation indices including SWIR do not provide additional information on the structure of the vegetation canopy.

The medium scale surface temperature (MUST) mission, studied in the frame of a European Commission (DG XII) contract, is a large swath (1200 Km), medium resolution (250 m) thermal infra-red imager mission devoted to retrieve the land surface temperature in order to serve various applications. These applications are firstly those concerned with the soil and vegetation water status (agriculture, irrigation and water resources management) as evapotranspiration and soil moisture can be inferred from surface temperature through relevant models. The other applications are either directly using the surface temperature (some frosts conditions assessment) or the air temperature that is itself derived from surface temperature extrapolation (urban heat island, some air frosts conditions). The project basically aimed to demonstrate the relevance and efficiency of the MUST mission products in the relevant application fields and to assess the economical benefits of the mission. Also in the course of the study the design of a medium resolution, large swath thermal imager, providing the appropriate performance required by the users while compact and affordable, was produced. Finally the operational implementation of the system and especially the ground segment was considered.

We present a simple, three-dimensional vegetation canopy thermal infrared exitance model for agricultural scenes. Computer graphics and ray-tracing techniques are used to estimate three-dimensional canopy view factors and scene shadows. The view factors are used to weight the individual contributions of soil and vegetation emission computed by steady-state energy budget formulations. We compare the three- dimensional model results to a one-dimensional formulation for an agricultural test site from the Hydrologic Atmospheric Pilot Experiment and Modelisation du Bilan Hydrique. The root mean square error is daylight brightness temperature for the one dimensional model was 2.5 degrees Celsius and 2.0 degrees Celsius for the three dimensional model.

The paper discusses the experience of creating a geoinformation technology for the use of AVHRR data with spatial resolution of 1.1 km for detection and evaluation of characteristics for fires the linear dimensions of which are by several orders lower than a pixel of image. The technology is based on the effective algorithm of detecting small area brightness anomalies which in some statistical sense differ from the surrounding background. The process of making a decision on the presence or absence of a signal is based on the methods of the statistical estimation theory. The Neumann- Pirson criterion is used as the initial detection principle which provides the detection with the constant frequency of false alarm. The evaluation of the area of the fire zone is carried out on the basis of complex interpretation of mathematical modeling results for the field of the image brightness, optimal evaluation of the signal amplitude and geodata. The developed information technology allows to detect fire zones the area of which is 10^-4 of the area of image pixel.

A methodology to detect vegetation burned areas is presented together with the results obtained for the African continent between November 1990 and October 1991. NOAA-AVHRR-GAC-5 Km images were used in this study. The spectral bands and indices used were land surface temperature (T_s) and the Global Environment Monitoring Index (GEMI). The time series was composited in weekly images using the minimum value composite of albedo (M_iVCA). After analysis of the weekly profiles on the main vegetation types that are affected by burning, a multitemporal multithreshold technique to detect burned pixels was developed [Burned Area Algorithm (BAA)]. This technique was based on the increase of T_s and a decrease in the GEMI after a fire occurrence. The results showed good agreement at the continental scale with the temporal and spatial patterns of active fires from the IGBP-DIS Global Fire Product. Comparison with a Landsat TM image classification showed good performance of the algorithm.

A temporal series of global coverage satellite data for the 12 month period April 1992 to March 1993 has been processed using a fire detection algorithm to record the positions of all vegetation fires observed. Fires are found to occur in almost all regions of the world, however 70% of all events detected are within the tropical belt. The spatial and temporal variations in the fire patterns are discussed and the main vegetation types that burn are identified. A methodology for parameterizing these distributions as a small number of classes is proposed and the geographical distribution of these classes is discussed.

This paper is development of spectropolarization nephelometry technique which allows to investigate the mechanisms of formation of radiation flux reflected by the plant leaf. Polarization degree angular dependencies of radiation reflected by the plant leaf were determined by the specially made goniometer installation according to specially developed technique. The potato leaves were taken as the research objects. Leaf radiation spectropolarization characteristics were received for the different potato sorts during two vegetation seasons. The relationship between spectral and polarization characteristics and potato sorts was studied by applied statistic methods. The connection between the position and magnitude of the polarization degree angular dependence maximum of reflected radiation and the potato sorts was discovered. It was shown that the ontogenetic development stage and sort or hybrid of potato may be diagnosed from analysis of the polarization degree angular functions.

Monitoring net primary productivity (NPP) and assessing site potential at the landscape level are central issues for sustainable landscape management practice. One of the foundations of classical forestry is the computation of forest productivity at the stand level. This computation of growth potential is usually based on a site index derived from measurements of height and age taken on dominant trees. The site index thus integrates the effect of the three main components of forest productivity: vegetation characteristics, climatic environment and site properties. However useful, site index-based methods cannot discern which part of the overall productivity is due to any of these three components. With an increasing demand for ensuring the sustainability of our forest practices, and with the uncertainty engendered by the possibility of climatic change, we now need tools to quantify the intrinsic productivity of a site, and the effect of external factors on this productivity. The ECOLEAP (extended concentration to link ecophysiology and forest productivity) project address these concerns. The overall objective of the ECOLEAP project is to develop a knowledge base from which tools to predict and monitor forest productivity and health will be developed. More specifically, the project will focus on three specific aspects. The first is the measurement of net primary productivity (NPP) in major eastern forest ecosystems, and, within each ecosystem, across a climate or fertility gradient. The second is the determination of functional relationships between specific biophysical factors, related to site, climate and species composition, and ecosystem NPP. The third is to develop tools to predict and monitor the sustainable potential NPP of major forest ecosystems under natural and managed scenarios. The three major forest types under study in ECOLEAP are the sugar maple, balsam fir and black spruce forests.

In this paper, a model based recognition and classification method for surface texture of vegetation from aerial sequence of images is presented. The image sequences are assumed to be acquired by a video camera (RGB-CCD system) from an aeroplane, which moves linearly over the scene. The objects in the scenes being considered in this paper, are agricultural fields. The classes of agricultural fields to be distinguished are determined by the type of crop, e.g. potatoes, sugar beet, what, etc. In order to recognize and classify these fields from aerial sequence of images, a common approach is in the use of surface texture. Here the circular symmetric auto- regressive (CSAR) random model is used for texture analysis. By manipulating the estimated value against its real value, the characteristics of a texture image may be determined. A hypothesize-and verify algorithm is used for model recognition. Based on all kinds of models, classification for surface texture of vegetation from aerial sequences of images is realized.

This study analyzed a natural site located in Central Italy which is a part of the Circeo National Park. An integrated approach was developed to correlate remote sensing TM data with field measurements of Leaf Area Index (LAI). Six vegetation types were discriminated by a supervised classification of the Circeo forest. Approximately 80% of the surface of the territory analyzed is dominated by natural mixed oak woody communities. Pine reforested areas are also present. LAI field measurements were correlated with normalized difference vegetation index (NDVI) obtaining a high correlation (y equals 15.587X^2.2967; r² equals 0.88). An estimation of LAI for the entire forest was performed and an LAI map created. The correlation between the measured and the estimated LAI was also high (r² equals 0.91). The study shows the potential of spatial scale integration to analyze and to monitor plant coenosis in Mediterranean areas.

Experimental investigations of the fluorescence intensity of plants in red and ultraviolet spectral ranges induced by the laser radiation have been carried out during one year. Dependence of the quantum yield of chlorophyll a fluorescence on plant species has been established and investigated. The largest range of seasonal variations of the fluorescence intensity was observed for the deciduous trees. Seasonal variations of the fluorescence intensity have the tendency to insignificant variations for the coniferous trees. Application of the fluorescence method to the remote specific categorization of the plant tissue and determination of the chlorophyll content is shown to be promising.

Remote sensing technology requires fast and sufficiently accurate devices to take repetitive and less destructive soil moisture measurement techniques for validation of remotely sensed data. This study was conducted at Winfred Thomas Agricultural Research Station (WTARS) in Hazel Green, Alabama. The objectives of this study were to compare volumetric water content values measured with the time domain reflectometry (TDR) and water content reflectometry (WCR) instruments to the values obtained by the standard gravimetric technique for the upper soil depth and to examine the performance of the different types of soil moisture sensors and the effect of the probe length on the accuracy of soil moisture determination. From Huntsville '96 field research, we found that the emitting depth is 5 cm or less, possibly as low as 1 cm. This suggests that, in order to validate remotely sensed data, it is necessary to have fast and sufficiently accurate instruments to take repetitive and non-destructive soil moisture measurement to measure soil moisture. Our results indicated no significance difference between the Delta-T 6 cm probe output with GSM, MESA 10 cm probe output with GSM, and WCR30 and 20 cm probe output with GSM measurements. Even though the standard gravimetric technique is very reliable to measure soil moisture content, it is relatively time consuming and very destructive. Therefore, it may not be used for repetitive measurement at exactly the same location. The different types of TDR and WCR probes we tested can be used for measuring the moisture content. Except the WCR 5 and 10 cm probes, all probes tested in this experiment provided similar results. Therefore, this probe can replace the traditional gravimetric technique as long as the proper calibration is performed for a range of soil moisture and soil types.

Emerging techniques for estimating soil moisture profiles combine inverse radiative transfer models (RTMs), constrained using soil hydrology models, with microwave brightness temperature (T_B) observations. The objective of this study is to simulate T_B with a coherent wave forward RTM and test the model's accuracy in estimating T_B and its sensitivity to measurement uncertainties. The field research was conducted in Huntsville, Alabama, USA during July 1996. A ground-based S- and L-band microwave radiometer (SLMR) was deployed to measure near-surface soil moisture while soil temperature and moisture measurements were made at five depths to 90 cm. Soil moisture profiles are estimated for bare and grass plots using the soil hydrology model (SHM) run at 20- minute time steps based on meteorological, soil and vegetation inputs. Sensitivity of the RTM to vertical resolution of input profiles and to uncertainties in input data and model parameters is assessed using five model simulation modes. These experiments permit evaluation of differences between measured and model profiles (simulations 1-2), enhanced vertical resolution (simulation 3), and the impact of remotely-sensed surface moisture content (simulations 4-5). The simulation modes are based on: (1) Measured moisture profiles. (2) Moisture profiles from SHM at the same vertical spacing as the measurements. (3) Same as (2) except with 1 cm soil layers. (4) SHM moisture profiles in which the upper 1 cm soil layer is adjusted using SLMR soil moisture estimates. (5) Same as (4) except the upper 5 cm soil moisture is adjusted by blending SLMR and SHM moisture values.

The objectives of this study were (1) to evaluate soil moisture variability under different land cover conditions and (2) to explore the effectiveness of geographic information system (GIS) technology in assessing the spatial and temporal soil moisture variability. The research was conducted on four 60 by 50 meter plots located on bare smooth soil, bare rough soil, mixed vegetation, and grass. From each plot, 5 cm depth soil samples were taken on a 10 by 10 meter grid at three different dates. Soil samples were oven dried to obtain the gravimetric soil moisture content. This study showed that GIS technology can be a valuable tool in accurately representing and examining the spatial and temporal variability of soil moisture under different soil cover conditions. Visual inspection of the 3-dimensional (3-D) representation of the soil moisture data showed notable variations within each plot among the different fields, and over time. Mean comparison was performed using the T-test to statistically evaluate and confirm the significance of these differences. Because the soil moisture measurements were taken on a relatively small area and within short time periods, although notably different, the spatial and temporal moisture variability was not statistically significant.

Soil moisture is an important component of analysis in many Earth science and related disciplines. Information about the entire profile can find a wide range of applications in many disciplines. Hydrological models can simulate soil moisture profiles, but there is usually limited subsurface information to constrain the models. Emerging science and technology to measure soil moisture with remote sensing offers a potential source of additional information from which to constrain soil hydrology models. Because passive remote sensing can provide soil moisture information for a thin surface layer of soil, the question becomes one of how to use this information to improve estimates of the soil moisture profile. This study attempts to shed light on this question by using a simple hydrology model (SHM) and with data collected during a microwave remote sensing experiment in Huntsville, Alabama during July 1996 (Huntsville '96). This study shows how the errors in the estimation of soil moisture increase as the sampling interval of meteorological data increases. The root mean square error (RMSE) from the baseline almost triples (i.e. from 0.0352 to 0.0810), as the sampling interval is increased from 6 hr to 12 hr. These errors can be reduced by half if we periodically update the modeled soil moisture estimates with a method that assimilates microwave remote sensing soil moisture estimates with the SHM soil moisture profile. Thus, this study attempts to extend the soil moisture information on the surface layer by microwave remote sensing to the entire profile using SHM.

The objective of this paper is to investigate the possibility of soil moisture retrieval from radar backscatter data in sugar beet fields. The analysis is based on a simulation study using two models capable of computing electromagnetic backscattering from a vegetated surface, viz. the model developed by Karam et al. and the model developed by Lang. First, we validate the models based on data from the AGRISCATT'88 field campaign, held in Flevoland, The Netherlands. The data collected during this campaign allows us to test the model predictions under different soil surface and canopy conditions and for different radar configurations. In general, both models are capable of mimicking the change in backscattering due changes in radar configuration and surface- vegetation characteristics. Next, both models are subjected to a sensitivity analysis with respect to different surface and canopy parameters. Based on this sensitivity analysis it is concluded that estimates of surface soil moisture content under a medium sugar beet cover (15 cm high crop) from L-band radar observations is only possible within 10% accuracy. For a fully developed sugar beet field (50 cm high crop), soil moisture retrieval is not possible.

Knowledge about soil moisture is important for a number of applications and synthetic aperture radar systems have been shown to be a useful source of data for this information. RADARSAT, with its steerable antennae and operational status, can provide timely coverage at a variety of swath coverages and resolutions. However, to make effective use of these various products careful consideration of the differences between the various beam modes and positions is needed. This paper describes work being done at the Canada Centre for Remote Sensing and the Universite de Sherbrooke to establish an approach to utilize retro-calibration information together with current information inherent in RADARSAT products to calibrate Standard mode data for soil moisture estimation. Work is also described which is leading to a first order correction for incidence angle as a function of land-cover in an agricultural environment to further develop this capability of RADARSAT for soil moisture estimation.

The results of experiments for soil erosion determination with the use of dual-polarization radar set at wavelengths of 3 and 0.8 cm are presented. It is shown that the specific radar cross-section (RCS) is a function of soil erosion at the range of incidence angles from 35 degrees to 60 degrees. The sensitivity of soil backscattering to erosion is more high when the ratio of RCS for HH and VV polarizations is used. The best description of surface roughness spatial spectra is fractal one. The results of image processing obtained by airborne radar remote sensing system of K_u-band with dual- polarization reception are discussed and the comparison of results of soil erosion determination by radar remote sensing techniques with in situ measurements is made.

Many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture and portray the spatial heterogeneity of hydrologic processes and properties that one encounters in drainage basins. The hydrologic procesess that may be detected include ground water recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential ET, and information about the hydrologic properties of soils and heterogeneity of hydrologic parameters. Microwave remote sensing has the potential to detect these signatures within a basin in the form of volumetric soil moisture measurements in the top few cm. These signatures should provide information on how and where to apply soil physical parameters in distributed and lumped parameter models and how to subdivide drainage basins into hydrologically similar sub- basins.

In this study spatially distributed and semi-distributed hydrological-related parameters, such as the Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), albedo and surface temperature, were evaluated by means of multitemporal optical remotely sensed data and field radiometric measurements acquired in different hydrologic conditions of the Virginiolo catchment (Italy). Land use land cover classifications were performed using Landsat Thematic Mapper (TM) data of spring and summer seasons. Digital counts were converted into calibrated radiance values and, after atmospheric correction, reflectance measurements were obtained. To estimate the spatially distributed LAI values and their changes related to the modifications of environmental and agrometeorological conditions within the catchment area, an empirical relationship between NDVI and LAI for Mediterranean areas reported in literature was used. Broadband surface albedo was estimated from spectral reflectance measurements obtained from the TM narrow bands following Brest & Goward's approach, and surface temperature was derived from the TM channel 6. Radiometric and thermoradiometric measurements, collected over selected fields were used to estimate the same hydrological-related parameters. When satellite images are not available, due to the presence of clouds, such parameters may be used in a semi-distributed hydrological modeling.

One of the present efforts in the field of microwave remote sensing is to estimate soil water status throughout the soil profile using radiometers. This study describes a simple, ideal algorithm relating microwave brightness temperature (T_B) and soil water status in the upper (10 cm) and lower (greater than 10 cm) soil depths. The algorithm description considers a simple, homogeneous, and sandy soil system with negligible amounts of capillary-stored water, organic matter content, and surface roughness. The microwave T_B was estimated from the dielectric constant, k, as a function of the amount of water remaining in the soil during drainage. The effect of downward fluxing, free water on the value of T_B was greater and occurred over a shorter period than that of the slower draining water near field capacity. The predictability of the algorithm decreased as the moisture content decreased to that of approximately field capacity.

An understanding of the behavior of land surfaces at microwave frequencies is important for the purpose of rainfall estimation. This paper presents the results of the RISMOP experimental campaign (radiometric impact of surface moisture after precipitation). In an initial ground experiment soil and vegetation samples were observed from a height of 2 m at 23.8 and 50.1 GHz and at both horizontal and vertical polarizations. The observations were made under both dry and wet conditions. The emissivity of soil was observed to decrease by up to 0.35 between dry and saturated soil conditions. The Met Office research aircraft made passive microwave measurements over Central Spain at 23.8, 50.1, 89 and 157 GHz. The flights were coincident with ground observations of soil moisture and cover type. Three of the flights took place under dry conditions and the fourth occurred shortly after rainfall. The flight data indicates an increase in surface emissivity with vegetation cover of up to 0.1 under dry conditions and 0.2 under wet conditions. Significant decreases in surface emissivity were observed between dry and moist soil conditions.

At present there are two global wetlands datasets that define the areal fraction of wetlands in a grid. The dataset developed by Cogley was presented in ISLSCP Initiative 1. The other dataset was developed by Matthews and Fung and has been widely used in climate modeling. Both datasets are available at 1 degree by 1 degree resolution. The two datasets are similar for many areas of the world, but for certain regions there are large differences, particularly in Alaska, Siberia and Eastern Asia. With a view to improving the performance of our global hydrological discharge model for the lateral flow of water on the continents, we have tested several parameterizations which include the influence of fractional wetlands area within a gridbox. In order to be able to judge the representativeness of the two datasets we have derived two sets of global parameters for the hydrological discharge model. The discharge model was then applied to five years of daily values of runoff and drainage which are taken from an ECHAM4-T42 simulation using climatological SST. The discharge of several large rivers was simulated with these different parameter sets. From the comparisons between the simulated discharges and the observed discharge of the considered rivers we judge the quality of the two datasets.

This paper describes a method and results for the investigation of the recent hydrological changes in Aral Sea and Lake Balkhash of Central Asia using multi-temporal satellite data. Landcover change of the lakes and their vicinity from 1960s to 1990s were analyzed by comparing the landcover classification images. Using the analyzed satellite images, a bathymetric map and the meteorological observations, change estimation of water volume and levels, and analysis of water balance in lakes were carried out. It is presumed that the change in Aral Sea has been affected by human activities. Contrary to this, the change of lake Balkhash has been affected by both human and natural dimensions.

The aim of this study was to compare satellite Landsat-5 Thematic Mapper (TM) data with Airborne Thematic Mapper (ATM) data, for the detection of the trophic status of water masses. Study area is the Lake Iseo, one of the most important freshwater basin in northern Italy, located in the sub-alpine ecoregion. In accordance with the Organisation for Economic Cooperation and Development (OECD) the Iseo waters are defined as meso-eutrophic. Airborne Daedalus ATM AADS-1268 data were acquired on 14th July 1992 and Landsat-5 TM data on 1st September 1992. Multi-temporal comparison required adjustment of scene radiance due to atmospheric variations. To achieve this an integrally image-based method was employed. Airborne and satellite data were used to estimate turbidity, chlorophyll and suspended sediment load, by means of chromaticity analysis. Processing of thermal images for lake surface temperature determination was also addressed. The results confirmed previous knowledge on the trophic state of Lake Iseo, in agreement with traditional investigations. Remotely data were able to separate chromaticity of the waters, discriminating different turbidity patterns distribution and emphasizing the behavior of shallower waters infected by macrophytes.

The research problem is to reveal location and estimate total intensity of the filtration flows, that pass under the dam body from the reservoir-cooler and unload to the Pripyat River. With this aim the CARTE airborne-laboratory has provided remote sensing survey of the radiation temperature fields on the ground surface, the soil surface layer moisture and the underground water level depth. As a result of the survey data processing the zones of the wet soil with underground water level higher than ground surface level have been located. Within these zones the low value of T_rad was observed. The value of T_rad was determined on day time by increased heat debit on evaporation and large thermal inertia of the wet soil, retarding its heat by insulation. Such coincidence of positive W anomalies and negative T_rad anomalies made possible to draw conclusion that they were confined to the areas of the underground water unloading from the reservoir-cooler under the dam to the Pripyat River. By resulted data the estimation of the filtration loss value under the dam has been performed.

Approximately two-thirds of the tropical forest destroyed each year are caused by small-scale farmers that slash and burn the forest vegetation to plant crops and pastures. Characterization and diagnosis of these land-use systems are the main theme of this <<VEGETATION Preparatory Programme >> project based on three regions of the equatorial areas: Brazil, Peroo and Cameroon. To fulfill the requirements of the project, forest cover proportion was assessed from high (SPOT, Landsat) and low (NOAA-AVHRR) resolution images. Classification of high resolution images in forest/crop land classes gave good results, but with some confusions between classes (open forest/dense forest for example). These confusions were reduced when the short wavelength infrared was included in the classification process. In comparison, classification of the low resolution images gave a poor estimation of the forest cover which is all the more over- estimated that the forest is fragmented. Forest cover proportion was then estimated from low resolution images, using spatial modeling and spectral mixture modeling, namely the 'TREES' and 'COCKTAIL' methods respectively. These two methods gave very close global values of deforestation at a regional scale, but the 'COCKTAIL' method had the advantage to provide maps of forest cover, while 'TREES' provided only a regional value.

The potential of remote sensing to monitor indices of forest health was tested by examining the spectral separability of plots with different balsam fir, Abies balsamea (L.) Mill, vigor. Four levels of vigor were achieved with controlled experimental manipulations of forest stands. In order of increasing vigor, the treatments were root pruning, control, thinning and thinning in combination with fertilization. Spectral reflectance of branchlets from each plot were measured under laboratory conditions using a field portable spectroradiometer with a spectral range from 350 - 2500 nm. Branchlets were discriminated using combinations of factor and discriminant analyses techniques with classification accuracies of 91% and 83% for early and late season analyses, respectively. Relationships between spectral reflectance measurements at canopy levels, stand vigor, and foliage quality for an insect herbivore will be analyzed further in support of future large scale monitoring of balsam fir vulnerability to insect disturbance.

Applying remote sensing techniques in a humid area variety of data were utilized, i.e., scanned high resolution KFA-1000 optical images, Landsat TM data, ERS radar data, digital elevation data, and aerogeophysical data (magnetics, resistivity). Lithological classification was performed by regional structural analysis (ERS-radar, DEM), regional distribution of land use (Landsat TM, KFA-1000), and integration of geophysics (radiometrics, resistivity). Structural analysis was substantially enhanced by the integration of aeromagnetic data to trace fault zones in the basement underneath sedimentary cover.

Reflectance (0.4 - 2.5 micrometer) and transmittance (2.5 - 25 micrometer) laboratory spectra of sedimentary and metamorphic rocks from different geologic settings were analyzed and classified, and used for the simulation of hyperspectral (MIVIS) response. The analysis regarded both freshly cut and exposed rock surfaces. Classification was based on absorption features forming significant associations that fully characterized groups of rocks. In carbonate rocks, the dominant spectral features in the VIS-NIR resulted from the fundamental mineralogy, whereas within overall silicatic rocks the discrimination was based on secondary mineralogic phases, that resulted spectrally dominant. In transmission spectra of silicatic rocks, spectrally dominant features, due to different bounding of Si⁴⁺ ion, allowed further differentiation between rocks not discriminated in the reflectance spectra. Classification of spectra of exposed surfaces did not significantly diverge from that of the freshly cut surfaces, apart from heavy lichen coating.

Long Valley caldera, California, is a site of extensive volcanism, persistent seismicity, and uplift of a resurgent dome, currently at a rate of approximately 3 cm/year. Airborne laser altimetry was used to determine the surface topography of the region in 1993. A repeat mission occurred in 1995. Three different laser altimeters were flown, dubbed ATLAS, SLICER and RASCAL. Data processing consists of the combination of the aircraft trajectory and attitude data with the laser range, the determination of an atmospheric delay, laser pulse timing errors, laser system biases, and data geolocation to obtain the position of the laser spot on the ground. Results showed that using the ATLAS and SLICER instruments, the elevation of an overflown lake is determined to precisions of 3.3 cm and 2.9 cm from altitudes of 500 m and 3 km above the ground, and approximately 10 cm using the RASCAL instrument from 500 m above ground. Comparison with tide gauge data showed the laser measurements are able to resolve centimeter- level changes in the lake elevation over time. Repeat pass analysis of tracks over flat surfaces indicate no systematic biases affect the measurement procedure of the ATLAS and SLICER instruments. Comparison of GPS and laser-derived elevations of easily-identifiable features in the caldera confirm the horizontal accuracy of the measurement is within the diameter of the laser footprint, and vertical accuracy is within the error inherent in the measurement. Crossover analysis shows that the standard error of the means at track intersection points within the caldera and dome (i.e., where zero and close to the maximum amount of uplift is expected) are about 1 cm, indicating elevation change at the 3 cm/year level should be detectable. We demonstrate one of the powerful advantages of scanning laser altimetry over other remote sensing techniques; the straightforward creation of precise digital elevation maps of overflown terrain. Initial comparison of the 1993 - 1995 data indicates uplift occurred, but filtering is required to remove vegetation effects. Although research continues to utilize the full potential of laser altimetry data, the results constitute a successful demonstration that the technique may be used to perform geodetic monitoring of surface topographic change.

In this study geological and geomorphological remote sensing investigation methodologies were applied to define the role of tectonic and neotectonic features in controlling the evolution of the Triest Karst territory, located at the Italian- Slovenian border. A Landsat TM image of the study area, has been visually interpreted using different products, with different information content, resulting from standard processing, in order to recognize main textural and structural characteristics of the area. The processing was aimed to enhance morphological (drainage networks, landmass denudation stages) and structural features (lineament pattern), as well as to identify main land-systems. Morphological, structural and landform elements were integrated to define some geomorphological-structural units having their own specific attributes. Structural trends have been recognized by means of rose diagram representations of lineament azimuth-frequency and cumulative-length distributions. Analysis of lineament frequency data, performed individually one each geomorphological-structural unit and on the study area as a whole, reveals that structural trends are strictly unit- dependent, and generally in agreement with regional structural models and focal mechanisms solutions reported in literature, with NE-SW dominant meso-alpine thrust faults reactivated with transpressive components during the neo-alpine phase and with more relevant dextral strike-slip movements recently, consistently with a NNW movement of the subthrusting Adria Plat, and an hypothetical counterclockwise rotation of the Istria peninsula.

The synthetic aperture radar (SAR) data acquired from the satellites ERS-1 and ERS-2 facilitate the extensive and astonishingly precise investigation of small displacements of the Earth's surface. Measurements of displacements are possible by differential SAR interferometry (D-InSAR) with centimeter accuracy. A detailed description of the D-InSAR system is presented to clarify the basic observation procedure. The D-InSAR system is an extension of the operational InSAR processor 'GENESIS' developed by the German Aerospace Research Establishment (DLR). The modular concept of the D-InSAR system permits a choice of different algorithms. Accordingly, the displacement can be extracted from an interferogram using a digital elevation model (DEM) as well as from two interferograms. Both techniques are illustrated and compared by a common data set. The geocoding and the various visualizations of the resulting data set support an easy application of this monitoring procedure in geosciences. Iceland is an especially suitable test site for differential SAR interferometry, because of its active tectonics, volcanism and flowing glaciers. Results of two Icelandic test sites are presented as applications.

In the North Western sector of the Alps an intense brittle tectonics overprints the nappe stack and related ductile deformations. On a regional scale, different brittle structural sets can be identified. The main purpose of this work was to test the reliability of optical and SAR data to identify new lineaments and to test their mutual interference in a collisional orogenic belt. ERS-1 Geocoded Terrain Correct data, provided by the Italian Processing and Archiving Facility (I-PAF) were analyzed and compared with optical data. These products were verified to be essentially complementary by geological interpretation. As an integrate result, the lineament length and orientation fit well the kinematic model of the study area, obtained through field analysis and apatite fission track datations (AFT) on differential uplift. Moreover it was also identified a close relationship between lineament sets and deep-seated gravitational slope deformations.

As part of our ongoing multisource data research program a groundwater vulnerability model was implemented within Arc/Info^TM, for the Lachute Area, near Montreal in Quebec, Canada. The model used was the DRASTIC model, initially developed in the United States and now recognized by Canadian and American government agencies (Aller et al., 1987). The objective of the present project was to develop an error propagation model for the evaluation of the reliability of the DRASTIC model. DRASTIC uses seven different parameters which influence groundwater vulnerability. These parameters are: depth to water, recharge, aquifer media, soil type, impact of the vadose zone and hydraulic conductivity. Each element is weighted according to its own influence on vulnerability. The DRASTIC index is obtained by the weighted summation of the rating attributed to the different parameters according to the relations incorporated in the DRASTIC model. For a homogeneous area: Index equals D_wD_r plus R_wR_r plus A_wA_r plus S_wS_r plus T_wT_r plus I_wI_r plus C_wC_r where X_w is the weight attributed to each parameter and X_r is the rating attributed to each parameter according to DRASTIC charts. The necessary data used for evaluating each model parameter originates from various sources including point data from drill holes, digitized maps, a digital elevation model and a Landsat TM image classification. As a final product, a vulnerability surface of the area in raster format is obtained. Two different approaches could have been considered for the characterization of error: a stochastic simulation of the model or analytical error propagation. In this paper, the second approach is presented because the DRASTIC type of model contains too many parameters for straightforward simulation.

An object-based approach for land use change detection at urban-rural fringe areas has been built and implemented in this research. This approach was used to generate knowledge from (1) thematic data: historical land use, slope, and contour data, (2) land cover and land use data produced from the Landsat TM data, and (3) image texture measurements: correlation and entropy. The generated knowledge was then used to provide evidence for inferring land use changes. Results obtained from the research area, namely the Tameside District, shows this approach has successfully identified land use object changing from agricultural land use to a mixture of residential and agricultural land use.

Stone surface monitoring of historical buildings is of interest in the planning of restoration work, both for assessing biodeteriogen growth and for detecting the spectroscopic features of the surface itself. Laser-induced fluorescence (LIF) analysis yields strong signals in the near IR region due to algal depositions while signals through the visible region are useful for the characterization of the stone materials. This paper reports on the first experiments carried out in the framework of a joint project of LTH and IROE-CNR aimed at the fluorescence imaging of historical buildings. We have used a fiber-optical fluorosensor for performing point measurements, and a mobile fluorescence imaging lidar system for remote measurements at a typical distance of 60 m.

In the frame of the Territorial Planning the interaction between the physical and human systems and the interdependence of the second one is a newness, still now never explored. The central-easter territory of the Veneto Plain and the adjacent lagoon strip East of Venice have been investigated by RS- multispectral satellite SPOT images. The final aim was to reconstruct the physical dynamic characters and the system interactions to know better their significance in relation with the ancient human presence. Hitherto, particular attention has been dedicated to the geomorphological change phenomena and to the consequent location of the natural resources, considered as potential monitors of the human settlements. In this framework the Piave, Tagliamento and Isonzo rivers result to be the most making and modeling agents of the region. Besides, the territorial analysis has put in evidence a brittle tectonic model, explaining the lowering of the area as a result of Plio-Quaternary faulting. The model clearly has controlled and controls the morphological evolution of the plain and lagoon systems, with particular reference to the eastwards fluvial trend. In the plain region the land stability, certainly consolidate since pre-historic age, and the presence of abundant natural resources have permitted to the ancient man a complete use of the territory. This strong model is now too testified by the sins of different agrarian Roman networks, interacting and oriented in order to provide the maximum hydraulic functionality. In the lagoon basins, instead, the ancient anthropic settlements appear to be mainly controlled by the effects of the estuarine river dynamics, so that the site or settlement spread depends on the limited areas, that is islands and salt marshes.

This paper moves from the results of RADATT (rapid damage assessment telematic tool), a project funded by the European Commission -- DG XIII. The final goal of the developed system architecture was to sensibly reduce the effects of a devastating seismic event by providing the responsible agencies a rapid and reliable damage detection and estimation of the extent and location of the suffered area. This result has been accomplished by the integration, within a single user interface environment, of data access and standardization techniques, image processing tools, GIS technology, analytical modeling and communication tools. A two-phase operating model has been conceived. In the pre-event era, images and data about building and infrastructures are collected and analyzed exploiting GIS capabilities. Immediately after the occurrence of the earthquake, the system must be ready to receive near- real time satellite imagery of the affected area to be compared with the pre-event imagery data set. A correspondence between the integrated databases, within the GIS environment, and the real-time imagery is also established. The post-event imagery is then compared with the pre-event one, by means of different digital processing techniques to exploit the different resolution of satellite images. In this paper the capability of this quick change detection analysis, given the availability of the pre-event information in the GIS environment, is discussed.

TOPEX/Poseidon and ERS-1 altimeter data have successfully been used to study the mesoscale field in the Mediterranean Sea and to investigate the seasonal variability of the Sea Level and eddy statistics in this basin. The comparison between the two altimeter performance is very good and underline importance to combine the information of TOPEX/Poseidon and ERS-1 to study the Mediterranean mesoscale eddy field. Sea level anomalies maps every five days were produced using the both data sets by means of sub-optimal interpolation. A comparison between mesoscale features detected by the two altimeters and contemporaneous features observed using Sea Surface Temperature maps definitively proves the direct relation between sea level anomalies and the Mediterranean eddy field. The data collected ERS-SYMPLEX cruise have been used to verify the performance of ERS-1/2 and TOPEX/POSEIDON altimeters in the Mediterranean Sea. The ERS-SYMPLEX experiment has been carried out in the channel of Sicily during spring 1996 in order to make a direct comparison between SLA from ERS1/2 and TOPEX/POSEIDON altimeters and in situ data. During the cruise CTD and XBT casts have been done in the central and eastern regions of the channel, and particularly densely along selected altimeters' tracks at the same time of the satellite pass. Sea level anomalies have been computed and compared with the dynamic heights and with the main circulation features resulting from SYMPLEX cruise. The results definitively prove the capability of the two altimeters to correctly detect both basin and mesoscale features of the Mediterranean circulation. Collinear analysis along a repeated T/P track has also suggested potential use of SLA in order to detect barotropic component of currents in the channel of Sicily.

This paper describes the concept of implementation of a multipurpose high-transmission lidar based on a raster-type diffraction spectrometer designed for detection of a weak radiation of the ocean upper layer. The lidar technique of multiangular sounding without a priori setting of the lidar light scattering ratio was used for diagnostics of plane scattering hydrosol layers and thermocline.

The casi has the spatial resolution of about 3 m X 3 m at the ground level and its spectral resolution is about 6 nm. The wavelength range for the measurement is from 430 to 870 nm and the number of the bands is 72 bands. An airplane carrying casi flew over Kuroshima Island, Okinawa and acquired image data of Kuroshima Island and the surrounding sea area. The flight courses were 6 courses at the altitude of 9,000 feet and 2 courses of 6,000 feet. At the same time, spectral measurements of the sea surface and several coral reefs underwater were carried out at an area of coral reefs off Kuroshima Island. The supervised and unsupervised classification were applied to the casi imageries to extract and classify the area of coral reefs off Kuroshima Island. The produced classification maps of the coral reefs were compared with the ground truth map of coral reefs made by the professional divers to evaluate the results. The results showed significant similarity of the distribution pattern of corral reefs.

Seasonal and interannual variability of the sea surface temperature field in the Adriatic Sea is analyzed using a five years time series of daily AVHRR (advanced very high resolution radiometer) data. The data used are the 9 km resolution sea surface temperature maps obtained in the framework of the Pathfinder project. This spatial resolution allowed analysis of only basin and sub-basin scale features. Average monthly sea surface temperature maps for the entire studied period (1987 - 1991) are discussed. The analysis shows the absence of any permanent surface feature in the Adriatic Sea. The cyclonic circulation of the south Adriatic Sea is marked by a surface temperature minimum that recurrently appears in late autumn or early winter, i.e. in the preconditioning and deep water formation phase. During autumn the surface inflow of Ionian water is observed while the Adriatic outflow is more evident in winter. Results of an EOF analysis suggest that the intensity of the western coastal cold water plume and the north Adriatic thermal front vary from year to year. Other sub-basin features like the south Adriatic gyre also display year-to-year variability.

The value of the yellow substances absorption coefficient in the visible-light spectrum is a very important characteristics used in the optical classification of sea waters. This quantity also needs to be included in algorithms for the remote detection of optically-active sea water constituents. An extensive data base of measurements of optical parameters has been collected during series of cruises since 1993 in different water masses of the southern Baltic. The yellow substance absorption coefficient at wavelength 400 nm and yellow substance absorption spectrum slope coefficient were calculated, and the statistical distribution of values of those parameters in the three various waters masses (bay waters, coastal and open sea waters) is presented. The seasonal variability of both parameters in the three regions is analyzed. Results are discussed and compared of with published record of yellow substance properties and variability pattern of other optical properties in the Southern Baltic.

A remote sensing methodology for monitoring the coastal zone of the Black Sea is proposed. Aiming to assess different water quality parameters and to map their spatial distribution, several studies have been carried out in the Institute of Optoelectronics, Remote Sensing Department. The main steps of the synthesized methodology are presented in detail, insisting on some original algorithms. To illustrate the described methodology, Landsat MSS and TM images, together with SAR-ERS- 1 data, gathered over two different coastal areas of the Black Sea, have been used. The results are promising, in the sense that the methodology extracted was tested on several remote sensing data and the results obtained showed a good concordance with the 'in-situ' data.

An analytical solution of the two flow irradiance equations are presented and described for exploring applications regarding the spectral response signatures of water surface reflectance due to the conversion of direct collimated light to the diffuse irradiance field by elastic and inelastic scattering and absorption processes and effects. The conversion efficiency or rate of conversion of a collimated beam is modeled and results presented in terms of model sensitivity results to describe the (1) general effects of a collimated beam due to a source function undergoing inelastic scattering, (2) model results without the collimated component and the resulting model effects on predicted sensor derived water surface reflectance. The model results indicates the important role of bottom reflectance on the returned signal in relatively shallow water where scattering and dissolved constituents are in low concentrations. In deeper water or where the constituents are at higher concentrations, the fluorescence effect on reflectance will be small, depending on the conversion rate of the collimated light to the diffuse light and collimated source intensity. The model has potential applications to near nadir viewing geometry of a water column in estuarine and coastal waters or waters overlying coral reefs. The analytical solution to the two-flow equations developed by Bostater, et al. are thus shown to have transferability to problems in fluorescence research.

The successive orders of scattering method is used to solve the transfer equation in the ocean-atmosphere system including the polarization. The code is made fast by the use of the Fourier series expansion of the radiance. Through runs for conservative cases, we can assess that the relative accuracy of the code is of the order of few percent. We first applied to satellite radiance simulations the classical algorithm to determine for ocean case 1 waters the chlorophyll concentration showing that we can decouple the ocean and the atmosphere, first to apply atmospheric corrections assuming the water body as a Lambertian reflector, second to normalize the water leaving radiance Then, we emphasized the need to include the polarization to achieve correct estimates of the water leaving radiances; otherwise, the chlorophyll determinations are strongly affected.

A spectral model of downwelling and upwelling irradiance reflectance from and transmittance through a wind-ruffled sea surface is developed. Dependences for sea surface slope distribution based on Cox and Munk (1954) and the foam coverage of the sea surface based on Gordon and Jacobs (1977), both these distributions having been modified by the author, were used in modelling. Being direct functions of a dynamic factor, i.e. mean height of wind waves, they take the influence of environmental (hydrometeorological and geometrical) factors into account. Snell and Fresnel laws were applied to the light transmission through the surface. Spectral dependences of light refraction in the 350 - 18,000 nm range were taken into account. Polarization effects were neglected. On the basis of this model, a simplified polynomial method for calculating the real surface reflectance and transmittance of downwelling and upwelling irradiance is presented.

Vertical rainfall profile retrieval based on reflectivity data collected by spaceborne rain radars can be improved through the techniques that exploit an estimation of the sea surface normalized radar cross section (NRCS) as an additional information. However, errors that can currently be made in predicting the sea surface NRCS may significantly affect their performance. Therefore in this paper we first address the problem to evaluate the NCRS of the sea surface perturbed by rain, when observed at nadir. For this purpose, the dominant effect of ring waves generated by rainfall is considered. The joint effect of wind is also considered. The proposed model is based on the full wave model (FWM) theory. Some comparisons are made with an alternative, less flexible model based on the Integral Equation Model (IEM) theory, and partial comparisons are also made with experimental data, which authorize to consider the proposed model well grounded and exploitable for application. Then, we show that the model can be usefully exploited to improve rainfall rate vertical profile retrieval over the sea surface, in the case of nadir looking, single frequency radars.

The paper describes the results of experimental investigations and instrumental realization of remote method of laser induced breakdown spectroscopy (LIBS) for express diagnostics of highly toxic and radioactive elements in the water. As an example the samples of oxides of non-ferrous metals and uranium are used. The emission spectrum of materials is excited in non-equilibrium plasma of a laser spark. A laser source provides in the radiation focusing range at a wavelength of 10.6 mm the peak radiation density 10⁸ - 5 X 10⁷ W/cm², the pulse duration at half-altitude is 0.3 ms. On the atmospheric experiments the radiation focusing is performed using the Cassegrainian telescope with a large mirror 0.45 m diameter. Statistical data on laser spark initiation have been obtained at distances up to 250 m - - on the solid and liquid targets.

A model of marine primary production with a set of statistical relationships linking physiological parameter of the photoplankton with abiotic factors of the sea has been developed. The study is based on empirical data analyzed from about 3,500 stations of various ocean regions. The data comes from Polish and Russian expeditions as well as from literature.

The possibility of using natural fluorescence -- sun-induced chlorophyll a fluorescence (SICF) in remote sensing and/or contact investigations of chlorophyll a concentration (C_a) has often been discussed in recent years. The relationship between chlorophyll a concentration (C_a) and chlorophyll a fluorescence at 683 nm seems to evident and suggests a method of obtaining the C_a concentration on the basis of SICF intensity. Unfortunately this relationship is not as direct as we would like because SICF depends on numerous physiological properties of phytoplankton like fluorescence quantum yield and light absorption capacity which depend on an environmental factors. The influence of these parameters on SICF is shown in this paper and the relationships are presented. Using these we made attempt to achieve the direct functional dependence between the natural fluorescence (obtained from the upward reflectance coefficient spectrum measured at 665, 683 and 710 nm) and the chlorophyll a concentration. The analysis carried out in this study shows that the possibility determining C_a concentrations is limited to great optical depths in the sea ((tau) greater than 3). However using SICF for estimation C_a in the surface layer is probably impossible.

The influence of the illumination by the direct sun light and the diffuse light of the sky on the spectral structure of the apparent optical properties of seawater is studied. The resulting formula of this paper couples the sea diffuse reflection coefficient with the angular distribution of the natural light and the inherent optical properties of the seawater. This work uses a self-consistent approach to solve the radiative transfer equation. That approach was developed earlier to calculate the apparent optical properties including the diffuse reflection coefficient. A model of the inherent optical properties of seawater is proposed. This model expresses the inherent optical properties through the concentrations of chlorophyll, yellow substance, and biogenic and terrigenic hydrosols. The transformations of sea optical signatures, due to the changes in illumination and concentrations of suspended and dissolved matter, are analyzed. It is shown that the atmospheric optical parameters and the sun elevation angle significantly influence optical signatures of the upwelling light. The effective wavelength -- the parameter that is weakly dependent on the conditions of illumination -- is proposed.

The spectral values of remotely obtained radiance reflectance coefficient (RRC) are compared with the values of RRC computed from inherent optical properties measured during the shipborne experiment near the West Florida coast. The model calculations are based on the algorithm developed at the Naval Research Laboratory at Stennis Space Center and presented here. The algorithm is based on the radiation transfer theory and uses regression relationships derived from experimental data. Overall comparison of derived and measured RRCs shows that this algorithm is suitable for processing ground truth data for the purposes of remote data calibration. The second part of this work consists of the evaluation of the predictive visibility model (PVM). The simulated three-dimensional values of optical properties are compared with the measured ones. Preliminary results of comparison are encouraging and show that the PVM can qualitatively predict the evolution of inherent optical properties in littoral waters.

Differential equations for the transmittance and the diffuse reflection coefficients of the stratified sea are obtained. To simplify starting radiative transfer equation, the approach uses experimental dependencies between mean cosines of underwater angular radiance distribution. The resulting equation for the diffuse reflectance coefficient is of a Riccati type. For the homogenous sea with arbitrary combination of inherent optical properties, that equation is solved analytically. For vertically inhomogeneous sea it is solved approximately. The resulting formula expresses diffuse reflection coefficient through the profiles of inherent optical properties of seawater and bottom depth and albedo. The results of calculations with main formula are compared with the Mont Carlo computations. It was found that the precision of this theory is about 15% and it is comparable with the precision of contemporary in situ measurements.

The Arcachon tidal inlet (France) is a sandy place where tidal currents, swells and storms produce important sand movements. For example the emerged sand banks move several tens of meter a year. To study and understand these movements traditional methods are often inefficient. Remote sensing seems to be the best means to follow and quantify year after year sand movements. Two SPOT scenes have been processed to carry out bathymetric maps. From these maps we extrapolated both channels' and sand banks' movements and computed the sediment volumes between the water surface and a depth of 5 meters. Below this depth, the radiances keep a constant value whatever the depth change.