Fernando Consalvi

Atmospheric water vapor effects on spaceborne interferometric SAR imaging: Comparison with ground-based measurements and meteorological model simulations at different scales

Spaceborne Interferometric Synthetic Aperture Radar (InSAR) is a well established technique useful in many land applications, such as monitoring tectonic movements and landslides or extracting digital elevation models. One of its major limitations is the atmospheric variability, and in particular the high water vapor spatial and temporal variability, which introduces an unknown delay in the signal propagation. On the other hand, these effects might be exploited, so as InSAR could become a tool for highresolution water vapor mapping. This paper describes the approach and some preliminary results achieved in the framework of an ESA funded project devoted to the mitigation of the water vapor effects in InSAR applications. Although very preliminary, the acquired experimental data and their comparison give a first idea of what can be done to gather valuable information on water vapor, which play a fundamental role in weather prediction and radio propagation studies.

Cloud liquid models for propagation studies: Evaluation and refinements

The Salonen cloud model currently in use in propagation and remote sensing simulations is analyzed at two independent sites: the ARM SGP site in USA, and the FUB site in Pomezia, Italy. The humidity threshold function is evaluated by using a ceilometer located at SGP and an otimization of such threshold is proposed. The cloud water model is assessed by comparing simulated brightness temperatures (TBs) with those measured by a dual-channel radiometer at 23.8 and 31.4 GHz. At SGP, the Salonen model is also tuned to the radiometer TBs. Then, the Salonen model, its modifications, and a model developed based on the outputs of numerical simulations are all evaluated at the site of Pomezia, in Italy, by comparing simulated TBs with measurements from a dual-channel radiometer at 23.8 and 31.65 Ghz.

Validation of MERIS water vapour in the central Italy by concurrent measurements of microwave radiometers and GPS receivers

This paper concerns the validation of the atmospheric integrated precipitable water vapour (IPVW) product of the MERIS instrument on board of ENVISAT satellite. The validation is performed both at specific locations and over an extended area. The first comparison is performed with respect to the measurements of ground based instruments (microwave radiometers, GPS receivers, radiosoundings). The second assessment is based on IPWV maps of the Tyrrhenian area that are produced by geostatistical interpolation of the measurements of a network of GPS receivers (over land) and measurements of Special Sensor Microwave Imager Radiometer (over sea). The preliminary results show that the standard ESA algorithm for MERIS underestimates IPWV values both over land and sea backgrounds.

Inversion techniques for ground-based microwave radiometric retrieval of precipitation columnar contents and path attenuation

Nonlinear inversion algorithms are developed to invert ground-based radiometric measurements for different sets of frequency channels and precipitation regimes. Both statistical regression estimators and feedforward neural networks are applied and compared using synthetic data sets from 6 to 50 GHz. An experimental validation is carried out using data collected by the ITALSAT ground-station (near Rome, Italy) equipped with 3 beacons at 19.7, 39.6, and 49.5 GHz together with a multi-channel radiometer at 13.0, 23.8, and 31.6 GHz. Results in terms of comparison between measurements and predictions for a rain event are finally discussed.