THE IMPORTANCE OF SCATTEROMETER WINDS IN THE EXTRACTION OF WIND FIELD FROM SAR IMAGES (Abstract/Poster in convegno)

Type
Label
  • THE IMPORTANCE OF SCATTEROMETER WINDS IN THE EXTRACTION OF WIND FIELD FROM SAR IMAGES (Abstract/Poster in convegno) (literal)
Anno
  • 2011-01-01T00:00:00+01:00 (literal)
Alternative label
  • FRANCESCO DE BIASIO;STEFANO ZECCHETTO; (2011)
    THE IMPORTANCE OF SCATTEROMETER WINDS IN THE EXTRACTION OF WIND FIELD FROM SAR IMAGES
    in EUMETSAT/ ESA Scatterometer Science Conference, Darmstadt, Germany, 11-13 April 2011
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • FRANCESCO DE BIASIO;STEFANO ZECCHETTO; (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto
  • The wind field extraction from SAR images is still problematic due to the difficulty of inferring the wind direction from single look radar measurements without external information. This parameter may be inherited from the wind field simulated by numerical models, or directly retrieved from the backscatter signatures in the images using spectral analysis, spatial local gradient, or wavelet related methods. All the methods need validation, since the variety of the geophysical phenomena imaged by SAR could interfere with the selection of the features related to the wind. Even more it is true when the application of the wind retrieval from SAR is made in coastal areas and regional seas, where meteorology may be strongly influenced by local circulations and orography. In this framework it is of paramount importance to have a reliable wind data set, to cope with the validation of the methodology and the related algorithms. In our opinion, the only reliable data set available to carry out this fundamental validation is represented by the scatterometer data which, despite their resolution coarser than that of SAR winds, have been demonstrated to be reliable, sometimes more than the atmospheric hindcasts by Limited Area Models. This is why our automatic procedure of downloading ASAR wide swath images and computing the wind field by the 2-D wavelet methodology we developed includes in the results the available scatterometer winds. Examples of SAR and scatterometer wind fields will be shown and commented. (literal)
Note
  • Poster (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • ISAC-CNR (literal)
Titolo
  • THE IMPORTANCE OF SCATTEROMETER WINDS IN THE EXTRACTION OF WIND FIELD FROM SAR IMAGES (literal)
Abstract
  • The wind field extraction from Synthetic Aperture Radar (SAR) images is still problematic due to the difficulty of inferring the wind direction without external information. The wind direction may be inferred by means of numerical models, or retrieved from the backscatter signature in the SAR image, using spectral analysis, spatial local gradient, or wavelet related methods [1,2,3,4]. Unfortunately, the variety of geophysical phenomena imaged by SAR often interferes with the selection of the features related to the wind, and even more in coastal areas and regional seas, where meteorology may be strongly influenced by local circulations and orography [5]. Thus, the validation of the wind fields obtained from SAR images against a truth data-set is the premise to acknowledge SAR winds methodologies. In our opinion, the only realistic data set to carry out this fundamental validation is delivered by scatterometer observations. Despite their resolution is coarser than that obtainable from SAR, they have been proved to be reliable, sometimes more than the atmospheric hindcasts by Limited Area Models [6]. An automatic near real time system to perform SAR wind evaluation from ENVISAT Advanced SAR (ASAR) Wide Swath (WS) SAR images has been set up at the premises of the Institute of Atmospheric Sciences and Climate (ISAC) in Padua, Italy. Here the ASAR images, downloaded from the European Space Agency (ESA), are analyzed and the sea surface wind vector computed by the 2-D Continuous Wavelet Transform (2DCWT) methodology, while scatterometer data are also collected to verify the SAR wind against remote sensing observations. (literal)
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