Weather and climate models requires global precipitation measurements because their performance are affected by the release of latent heating. Such kind of measurements is also required to facilitate management strategies for hydrology, transportation and agriculture. In the last three decades most of our understanding of global precipitation has been provided by the measurements of spaceborne passive microwaves radiometers and Ku-band radars, such as the Precipitation Radar (PR) aboard the Tropical Rainfall Measurement Mission (TRMM) satellite. Unfortunately microwave radiometers are very sensitive to the scattering of ice in the upper regions of precipitating clouds which is poorly related to surface rainfall rates, and have a reduced resolution of several kilometers. Also PR has a resolution of a few kilometers so it can miss relative small precipitation cells. A new opportunity to investigate the structure of precipitating clouds is offered by Synthetic Aperture Radars (SARs) operating at X band. Their nominal spatial resolutions is of the order of meters even if it is degraded to the order of hundreds of meters when observing precipitating clouds, due to the turbulent motion of the storm hydrometeors. X-band SAR are traditionally considered all-weather sensors but since many years spaceborne platforms has provided experimental evidences that this kind of sensor is sensitive to rainfall. The interest towards X-band SARs is witnessed by several new platforms that are currently or will soon be placed in orbit, such as COSMO-SkyMed (CSK) and the TerraSAR-X (TSX). To the purpose of characterize spaceborne X-SAR precipitation response, we have developed a theoretical and numerical model accounting for the side-looking SAR geometry in which precipitation cells are produced by simulations of the System for Atmospheric Modeling (SAM) model. This framework will be used for sensitivity analysis and calibration of our X-SAR inversion framework in which quantitative rainfall signatures are estimated by X-SAR data. In this work we will introduce our forward model framework and we will show quantitative retrievals obtained by our inversion routines on a TSX 2008 case study, verified with co-registered weather radar (WR) imagery available during the TSX overpass.
Evidence of rainfall signature on x-band spaceborne synthetic aperture radar response by model analysis and spaceborne imagery / Mori, Saverio; Marzano, FRANK SILVIO; Pulvirenti, Luca; Montopoli, Mario; Chini, Marco; Weinman, James A.. - ELETTRONICO. - (2010). (Intervento presentato al convegno IEEE GOLD Conference tenutosi a Livorno nel 22 -23 May).
Evidence of rainfall signature on x-band spaceborne synthetic aperture radar response by model analysis and spaceborne imagery
MORI, SAVERIO;MARZANO, FRANK SILVIO;PULVIRENTI, Luca;MONTOPOLI, MARIO;
2010
Abstract
Weather and climate models requires global precipitation measurements because their performance are affected by the release of latent heating. Such kind of measurements is also required to facilitate management strategies for hydrology, transportation and agriculture. In the last three decades most of our understanding of global precipitation has been provided by the measurements of spaceborne passive microwaves radiometers and Ku-band radars, such as the Precipitation Radar (PR) aboard the Tropical Rainfall Measurement Mission (TRMM) satellite. Unfortunately microwave radiometers are very sensitive to the scattering of ice in the upper regions of precipitating clouds which is poorly related to surface rainfall rates, and have a reduced resolution of several kilometers. Also PR has a resolution of a few kilometers so it can miss relative small precipitation cells. A new opportunity to investigate the structure of precipitating clouds is offered by Synthetic Aperture Radars (SARs) operating at X band. Their nominal spatial resolutions is of the order of meters even if it is degraded to the order of hundreds of meters when observing precipitating clouds, due to the turbulent motion of the storm hydrometeors. X-band SAR are traditionally considered all-weather sensors but since many years spaceborne platforms has provided experimental evidences that this kind of sensor is sensitive to rainfall. The interest towards X-band SARs is witnessed by several new platforms that are currently or will soon be placed in orbit, such as COSMO-SkyMed (CSK) and the TerraSAR-X (TSX). To the purpose of characterize spaceborne X-SAR precipitation response, we have developed a theoretical and numerical model accounting for the side-looking SAR geometry in which precipitation cells are produced by simulations of the System for Atmospheric Modeling (SAM) model. This framework will be used for sensitivity analysis and calibration of our X-SAR inversion framework in which quantitative rainfall signatures are estimated by X-SAR data. In this work we will introduce our forward model framework and we will show quantitative retrievals obtained by our inversion routines on a TSX 2008 case study, verified with co-registered weather radar (WR) imagery available during the TSX overpass.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
