RESTRICTED only accessable in CEN/MPI network or via CliSAP login What does that mean?
Radar backscatter data measured by the EUMETSAT MetOP-ASCAT sensor are used to compute the wind vector over ice-free open water surfaces. The ASCAT sensor is a C-Band scatterometer which measures the surface radar backscatter along two about 500 km wide swaths parallel to its orbit with about 25 km spatial resolution at the Earths's surface. The ocean surface radar backscatter is a function of the ocean surface roughness which is in turn a function of the wind speed.
Remote Sensing Systems (REMSS, http://www.remss.com) used the EUMETSAT MetOP-ASCAT data to compute the surface wind vector at 10 m height above the ocean surface. This is done by using a so-called Geophysical Model Function (GMF) which has been developed specifically for MetOp-ASCAT (C-2015 GMF) paying special attention to extend the ocean surface wind speed data set produced from QuikSCAT Ku-Band data which ends in 2009. We refer to data set web page at REMSS: http://www.remss.com/missions/ascat and the references section for details. We refer further to the section about the data quality to learn more about potential limitations.
The product offered here is a modified version of the daily EUMETSAT MetOp-ASCAT ocean surface wind vector product v02.1 released by REMSS in April, 2016. The modification applied by ICDC is the conversion from flat binary into netCDF file format, the computation of the u- and v-wind vector components from wind speed and direction, and translation of the bit-wise to be read rain flag / rate information into two separate layers: a rain flag and a rain rate.
Last data set update at ICDC: May 10, 2019.
Period and temporal resolution:
Missing days: 2017: Jan. 2-4 & 12-19
Coverage and spatial resolution:
The data set offered here does not include any explicit uncertainty estimates for the variables themselves but a quality flag is included which allows to judge how successful the retrieval was.
Precipitation influences the measured radar backscatter intensity either directly by scattering of the microwave radiation by the precipitation particles or indirectly by adding to the water surface roughness due to precipitation particles impinging on the water surface. These areas are flagged invalid in this data set. The rain flag relies directly on ASCAT measurements while the precipitation rate is computed from brightness temperature measurements of other satellites taken within 3 hours to the ASCAT overpass. We note that ASCAT is less sensitive to precipitation and/or attenuation of RADAR radiation in the atmosphere / clouds than QuikSCAT because it uses C-Band instead of Ku-Band.
We refer to the section references for further information.
Remote Sensing Systems
When using the data please cite as follows:
Ricciardulli, L., Wentz, F.J., April 2016. Remote Sensing Systems ASCAT C-2015 Daily Ocean Vector Winds on 0.25 deg grid, Version 02.1, Santa Rosa, CA: Remote Sensing Systems. Available at www.remss.com/missions/ascat. Accessed from www.remss.com:, last access date: 2019-05-02. Downloaded in netCDF file format from the Integrated Climate Data Center (ICDC, icdc.cen.uni-hamburg.de) University of Hamburg, Hamburg, Germany.
In addition please add to the acknowledgements:
C-2015 ASCAT data are produced by Remote Sensing Systems and sponsored by the NASA Ocean Vector Winds Science Team. Data are available at www.remss.com.