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Global Wind Speed Retrieval From SAR

Horstmann, Jochen and Schiller, Helmut and Schulz-Stellenfleth, Johannes and Lehner, Susanne (2003) Global Wind Speed Retrieval From SAR. IEEE Transactions on Geoscience and Remote Sensing, 41 (10), pp. 2277-2286. IEEE.

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The global availability of synthetic aperture radar (SAR) wave mode data from the European Remote Sensing (ERS) satellites ERS-1 and ERS-2, as well as ENVISAT, allows for the investigation of the wind field over the ocean on a global and continuous basis. For this purpose, 27 days of ERS-2 SAR wave mode data were processed, representing a total of 34 310 imagettes of size 10 km x 5 km, available every 200 km along the satellite track. In this paper, two methods for retrieving wind speeds from SAR imagettes are presented and validated, showing the applicability of ENVISAT alike SAR wave mode data for global ocean wind retrieval. The first method is based on the well-tested empirical C-band scatterometer (SCAT) models, which describe the dependency of the normalized radar cross section (NRCS) on wind speed and direction. To apply C-band models to SAR data, the NRCS needs to be accurately calibrated. This is performed by a new efficient method utilizing a subset of colocated measurements from ERS-2 SCAT and model winds from the European Centre for Medium-Range Weather Forecast (ECMWF). SAR wind speeds are computed from the calibrated imagettes and compared to the entire set of colocated ERS-2 SCAT and ECMWF model data. Comparison to ERS-2 SCAT winds result in a correlation of 0.95 with a bias of 0.01 ms-1 and an rms error of 1.0 ms-1. The second approach is based on neural networks (NNs), which allow the retrieval of wind speeds from uncalibrated SAR imagettes. NNs are trained using the mean intensity of ERS-2 SAR imagettes and colocated wind data from the ERS-2 SCAT and ECMWF model data. Validation of the NN-retrieved SAR wind speeds to ERS-2 SCAT and ECMWF model wind data result in a correlation of 0.96 with a bias of 0.04 ms-1 and an rms error of 0.93 ms-1.

Document Type:Article
Title:Global Wind Speed Retrieval From SAR
AuthorsInstitution or Email of Authors
Horstmann, JochenGKSS
Schiller, HelmutUNSPECIFIED
Schulz-Stellenfleth, JohannesUNSPECIFIED
Lehner, SusanneUNSPECIFIED
Journal or Publication Title:IEEE Transactions on Geoscience and Remote Sensing
Refereed publication:Yes
In ISI Web of Science:Yes
Page Range:pp. 2277-2286
Keywords:Calibration, neural network, scatterometer, synthetic aperture radar (SAR), wind speed
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Entwicklung und Erprobung von Verfahren zur Gewässerfernerkundung (old)
Location: Berlin-Adlershof , Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Marine Remote Sensing
Deposited By: Bärbel Bolowski
Deposited On:21 Nov 2005
Last Modified:14 Jan 2010 20:19

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