Science Service System

Summary of Proposal OCE2822

TitleAssessment of the dependence of the X-band TerraSAR-X co-polarized and cross-polarized normalized radar cross sections and related parameters on the sea surface wind vector and on the acquisition geometry
Investigator Grieco, Giuseppe - Agenzia Spaziale Italiana, Center for the Interpretation of Earth Observation Data (CIDOT)
Team Member
Senior Milillo, Giovanni - Agenzia Spaziale Italiana, CIDOT
Senior PORTABELLA, MARCOS - INSTITUT DE CIČNCIES DEL MAR (ICM-CSIC), Physical Oceanography Department.
Full Professor Migliaccio, Maurizio - University of Naples, Parthenope, Department of Engineering
Senior Scientist Stoffelen, Ad - Royal Netherlands Meteorological Institute ( KNMI) , R&D weather
SummaryIn this announcement of opportunity, we propose toinvestigate the dependence of the Polarization Ratio (PR), the PolarizationDifference (PD) and the X-band TerraSAR-X Cross Polarized Normalized RadarCross Section (CP-NRCS) on the wind speed, the incidence angle, the wind direction and the sea state with the final aim of fitting a GMF for wind speed retrieval purposes, with a particular focus on high wind regimes. Furthermore, we want to investigate the dependence of the Doppler centroid on the wind vector and on the incidence angle with the aim of fitting a GMF. In addition, we propose to assess the dependence of the wavelength cut-off on the wind speed, on the sea state and on the incidence angle in order to fit another GMF. All this information will finally be used to retrieve the wind vector for the different wind regimes. In order to pursue these objectives, we need a large amount of dual polarized and single polarized images (both vertical and horizontal) acquired in StripMap and/or ScanSAR mode in the period going from the beginning of the TerraSAR-X mission up to 18 months ago. We are mainly interested in images acquired on the Western Mediterranean basin, on the Gulf of Mexico, on the East and West coasts of the US and Canada and on the tropical Atlantic and Western Pacific Oceans. These data will be collocated with all the available ancillary observations, such as the National Data Buoy Center (NDBC) buoy data, the Tropical Atmosphere Ocean (TAO)/TRITON and Prediction and Research Moored Array in the Atlantic (PIRATA) buoy data, the airborne Stepped Frequency Microwave Radiometer (SFMR) derived wind speeds provided by the NOAA HurricaneResearch Division (HRD), the wind and sea state information coming from the ECWMF ERA Interim reanalysis. A data subset will be used for the assessment of the dependence of PR and PD on wind speed, wind direction, incidence angle and sea state, as well as for fitting an X-band CP GMF. The availability of SAR images on the Mediterranean Sea will be used also to test and eventually revisit the XMOD2-GMF developed by Ren et al. 2012 for vertical co-polarized SAR images. Another data subset will be used to fit a GMF that relates the wavelength cut-off to the wind speed, the SWH or the wave age and the incidence angle and a GMF that relates the Doppler centroid to the wind vector and the incidence angle. The GMFs and Bayesian wind retrievals will be validated both under low to moderately high wind regimes and under extreme wind events by means of other useful data subsets. A particular emphasis will be given to the coastal areas. It is well known that scatterometer-derived wind fields are of lower resolution than those derived by SAR and that they lack observations near the coast (within 20 km off the coast approximately). SAR can potentially complement scatterometer data by covering the coastal gap and in addition provide validation of coastal scatterometer winds. As such, strong efforts will be spent in order to retrieve more reliable coastal wind fields. This project will not use any additional funding. NDBC, TAO/TRITON, PIRATA, SFMR and ECMWF data are free and no fund will be requested for human resources.

Back to list of proposals

© DLR 2004-2016