River discharge is an important quantity of the hydrologic cycle because it is essential for both scientific and operational
applications related to water resources management and flood risk prevention. Streamflow measurements are sparse and
for few sites along natural channels and, hence, they are not able to detect adequately the complexity of variation in
surface water systems. Therefore, in recent years, the possibility to obtain river discharge estimates through remote
sensing monitoring has received a great interest. In this context, the capability of the MODerate resolution Imaging
Spectroradiometer (MODIS) for river discharge estimation is investigated here. Thanks to a very short revisiting time
interval and a moderate spatial resolution (up to 250 m), MODIS has a significant potential for mapping flooded area
extent and flow dynamics. Specifically, for the estimation of river discharge, the ratio of the MODIS channel 2
reflectance values between two pixels located within and outside the river is used. Time series of daily discharge
between 2006 and 2010 measured at two gauging stations located along the Upper Tiber River basin (central Italy) are
employed to test the procedure. The agreement between MODIS-derived and in situ discharge time series is found to be
fairly good with correlation coefficient values close to 0.8.
In this work, a simple and robust technique, that allows for automatic identifying of surface materials by using Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) radiances was applied in order to recognize rocky outcrops in the area of the Pollino National Park (southern Apennines, Italy). Tests were made over an area which is topographically complex and geologically characterized by ophiolite-bearing units (Ligurian units), Meso-Cenozoic shallow-water carbonates (Pollino Unit) and Plio-Quaternary sediments. Among ophiolitic rocks, serpentinite was chosen as a test-rock as it is present in isolated outcrops in the test-area, besides subtending important environmental problems because it contains asbestos. Geological information, coming from field observations or geological maps, was used as input and in order to verify the results of the MIVIS data processing.
In southern Italy the Basilicata Region authorities are strongly active in monitoring the regional environment for planning actions to undertake. To this aim the Basilicata Region has been promoting dedicated remote sensing activities. The criteria adopted in starting the initiatives are based on the use of the best available technologies and their integration with standard methodologies (satellite and airborne data integrated with ground measurements) devoted to the best planning and management of the territory. Airborne surveys were deployed mainly to derive the main land cover and vegetative units to allows the outset of detailed studies of physical-chemical characteristics of the natural (geologic outcrop and vegetative species discrimination) materials in the park zones highly protected. The resulting thematic map at 1:10.000 scale is, in comparison with the available ones, has a better detail whether in term of number of classes depicted or in term of classes distribution. The spectral resolution of the data has also evidenced the aptitude of the land cover maps to describe local ecosystem and to derive local biophysical important variables useful for management implications and to allow a correct parameterization of the surface variables useful to the modeling community.
Physical parameters related to Earth surface and atmosphere show different behaviors when observed at different space-time scales by using both remote sensing or traditional ground based techniques. The main aim of this project was to investigate the information content degradation which results moving from the use of observations obtained by direct-punctual (ground-based), higher spectral/spatial resolution (airborne sensors), higher time-resolution, low cost and low spatial resolution (satellites), in the context of the activities related to natural and environmental risks monitoring in protected natural areas. Several observational techniques have been contemporary used during two fields campaigns in the Pollino National Park (Southern Italy): a) from ground by direct measurements of near surface parameters (from - 70cm of depth up to 200cm of height) as well as by radiosonde and radiometric measurements of surface and atmospheric parameters; b) using hyperspectral (MIVIS) and photographic aerial observations; c) from LANDSAT-TM, NOAAA/AVHRR and ADEOS/AVIRIS satellite sounders. Campaign data have been integrated on a GIS (including high resolution cartographic layers) and long term evolutionary trends (up to 20 years) also considered after the analysis of available historical, LANDSAT and NOAA, satellite records. This paper will present the main achievements of the project with special emphasis on the trade-off between expected performances and economical sustainability of different environmental monitoring strategies in an operational context.
Within the Pollino National Park environmental monitoring promoted by the Basilicata Region authorities (southern Italy), hyperspectral airborne data surveys were deployed to collect spectra images with higher spectral/spatial resolution. In order to define a standard atmospheric procedure to be applied to MIVIS data set, different radiative transfers code has been tested. Unfortunately generic correction procedures, like ATREM, widely applied to airborne hyperspectral data sets, could not be used for MIVIS data set because of the absence of the specific water absorption bands (0.94 and 1.14micrometers ) in its spectral region coverage. In this paper a technique to recover the right slope of the water absorption bands centered at 0.82micrometers , not measured by the MIVIS spectral resolution, is presented. The synthetic 0.84micrometers channel is spectrally recovered in place, by using the spectral behavior of each pixel. Channel simulations have been conducted on AVIRIS data sets resampled on the MIVIS NIR spectral channel curves and compared with the AVIRIS ones recorded at 0.84 micrometers . Data simulation has proved the efficiency of the method and the spectral coherence of the synthetic bands centred at 0.84(mu) +m. As a consequence the atmospheric correction code ATREM, with the help of appropriate contrivance to rescale the water vapour atmospheric amount, could be applied to the MIVIS data set by selecting, in the ATREM input file, only the water absorption band centred at 0.82micrometers .
In this paper we present an intercomparison between ground based lidar, radiosonde and satellite atmospheric water vapor measurements. Comparisons expressed in terms of water vapor profiles, obtained by Raman lidar and simultaneous ballonborne radiosonde, are reported and discussed. The deviation between the two profiles is smaller than 10 percent up to an altitude of 5 km. Furthermore, the intercomparison between lidar and radiosonde data and between lidar and satellite data is performed also in terms of water vapor columnar content. The agreement between lidar and radiosonde columnar content is better than 4 percent. Water vapor contour map are showed in order to demonstrate the high spatial and temporal variability of water vapor in the lower atmosphere. Difficulties in comparing lidar and satellite water vapor columnar contents associated to H2O spatial and temporal variability are discussed in the paper.
The main objective of this work has been to evaluate the potential of integration of satellite data and topographic factor, in order to achieve improved performance in forest fire danger estimation. Existing AVHRR-based fire danger estimation methods (a review is specifically made) aim at obtaining fire susceptibility classification exploiting, mainly, the temporal evolution of NDVI, and Surface Temperature (Ts). In this work fire danger estimation has been performed integrating satellite data with fuel type and topographic factors. In order to evaluate the reliability of the estimated indices, the time-space distribution of actual forest fires, provided by the Italian Forestry service, has been used. Preliminary results are very promising; they have shown that in the summer of 1996, a large number of forest fires occurred in the estimated higher danger areas.
Through this paper the authors propose a new approach for volcanic aerosols detection by satellite. By using only NOAA/AVHRR data at hands the proposed method seems able to detect eruptive volcanic clouds as well as long-period trends in stratospheric aerosol loading related to major eruptive events. Several examples of application to different events of volcanic emission are presented; some cases of Etna and Stromboli volcanoes have been investigated and an historical analysis has been performed in order to recognize stratospheric aerosols produced by Mount Pinatubo's eruption. In all cases the technique was able to detect anomalous particle loading in atmosphere, in an automatic way, without need of any specific transmittance model for the atmosphere or ancillary ground-based measurements. The main merit of this new approach is its effectiveness in recognizing field anomalies also in the presence of a highly variable background as well as its intrinsic exportability ensured by the use of thresholds which are local but automatically generate by using only satellite data at hands. By this way the proposed technique can be numbered among the others environmental applications of RAT approach in which it finds its origin.
The most commonly used fire detection methods based on AVHRR (Advanced Very High Resolution Radiometer aboard NOAA satellites) observations have been applied, in this work, to the Italian Peninsula, in order to assess their effectiveness and robustness in an operational scheme for fire monitoring in different areas. The analysis developed so far shows that unsuccessful results obtained from existing detection methods mainly depend on the use of generalized, fixed threshold values, in the fire-detection tests. A new fire-detection technique, based on the most general RAT (Robust AVHRR Technique) approach, is proposed in this work. It seems able to join good performances, typically associated with techniques based on locally tuned thresholds, with high operational exportability, achieved by an automated implementation scheme completely based on AVHRR data hands. Improvements achievable by using this new approach over the Italian Peninsula, have been evaluated (for several forest- fire events and different observational conditions) by comparison with the historical records of the Italian Forestry Service.
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.
Simultaneous water vapor measurements from satellite and ground based systems, have been performed in Napoli and Potenza throughout the last two years. Night-time water vapor profiles were provided by two lidar systems based on the Raman technique. The lidar system in Napoli, Italy is based on Xe:F excimer laser ((lambda) equals 351 nm), the system in Potenza, Italy is based on a Nd:YAG laser operating both on the 2nd (532nm) and 3rd (355nm) harmonics. Precipitable water (PW) measurements were provided during daytime by a grating spectrometer observing solar spectral irradiance at differentially absorbing channels in the wing of (rho) (sigma) (tau) water vapor band. Night and daytime PW measurements were provided using TOVS and AVHRR packages flying on NOAA satellites. Split window technique on two differentially absorbing AVHRR channels in the 11 micrometers region has been used in order to provide PW amounts with a spatial resolution of approximately 2 Km. The standard ITPP processing for TOVS package has been used in order to obtain PW estimates at lower spatial resolution (about 40 Km). Night and daytime radiosonde measurements have been performed during the last part of the campaign. All the simultaneous independent measurements have been analyzed and the results compared.
In order to produce temperature or water vapor profiles from infrared radiance measurements the detection of possible cloud contamination within the field-of-view is required. In most retrieval schemes a correction phase follows so that the inversion algorithm operates on clear column infrared radiances. In the present paper we describe an objective filtering scheme aiming at processing radiances, for each infrared measuring channel, to produce a field of cloud cleared values with sufficiently well defined statistical properties and error structures. Basically the method uses clear measurements only and treats cloudy data as unmeasured or missing data. Synthetic values of clear column radiances for HIRS/2 channel 4,7,13,8 are used as a test field. The results presented are retrieval of clear radiance fields from cloudy data sets, each consisting of the test field with instrumental noise added and a cloud mask defining whether each individual field of view is clear or not. Radiances defined as cloudy are consistently treated as missing data. The cloud masks used for the present exercise are obtained from processing of real data with a very high cloud content, in order to understand the behavior and quality of the algorithm in situations close as possible to worst real cases.
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