Wind Field from Satellite Scatterometer: data set description page


Data set source
Data use
Information on available Data
Data Processing
Data format
References
Data selection page
The ERS WiNd Fields (WNF) are distributed by the CERSAT . CERSAT wind processing facility produces ERS WiNd Fields based on the AMI level 1.5 product.

Data set source

  • ERS-2 polar satellite

    • Data use

    CERSAT-IFREMER consents that the FASTEX Central Archive distributes its products to the FASTEX scientists. The following Data Use has to be applied on the WiNd Fields (WNF).
  • Use of WiNd Fields are exclusively limited to the scientific community.
  • When using CERSAT-IFREMER data products in a publication, please cite the origin of the data and the handbook describing the product.

    Information on available data in the FASTEX Central Archive

  • native binary format
  • between 19970101:00Z and 19970301:00Z


    • Data processing:

    The processing is performed on the scatterometer (AMI-Wind) real time products (WSC.FDC). The processing unit is the acquisition pass made with WSC.FDP products. These products contain, for each point of measurement, three different values of the backscattering coefficient (Sigma naughts) taken at different incidence angles. The wind fields, WNF products, are computed from those data.
    Using the Sigma naughts, the wind speed and direction are estimated for each point of measurement by following three processing steps:
    • The different wind solutions fitting the sigma naughts are found. This process involves a backscattering model.
    • An ice mask is build up directly related to the error between measurement and backscattering model prediction.
    • To choose one wind solution, among those obtained in step 1 discarding the ice points, two general methods are used. This is called the ambiguity removal, this is done:
      1. By comparaison with meteorological wind fields.
      2. Or by probability of each measurement resulting from the comparison with the theorical results of the backscattering model


    Data format

    The format of data files follows a convention called CCSDS. It is a format convention largely used in satellite data distribution. The User manual for WNF products, and software to read the data, both provided by CERSAT, are sent with the data.

    Product size is 500km x 500km. Sigma naughts data are sampled every 25 km for the usual resolution products. Each product contains a header and 361 data records. It corresponds to 19 lines in the along track direction, each line containing 19 points.

    A data file contents the data from one satellite pass. The maximun number of products per pass is 88.

    Each data record includes the position, azimuth, incidence angle and Kp value for the 3 beams, speed and direction for the four first alias winds and for the interpolated meteorological wind, and the rank of the dealiased wind vector.


    References

  • information for ERS-2 Wind Fields, CERSAT on Internet: http://www.ifremer.fr/cersat/english
    acces to the CERSAT home page
  • For scientific contact on algorithms: Mr Yves Quilfen IFREMER-DRO/OS/LOS, BP70, 29280 PLOUZANE, France email: Yves.Quilfen@ifremer.fr
  • For ordering WNF products or get more information on CERSAT archiving and processing facility (PFAF): Mrs Sylvie POULIQUEN, IFREMER - CERSAT, BP70, 29280 PLOUZANE, France email: fpaf@ifremer.fr
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    Updated: 6 Nov 1998