New ASCAT Data Available

Date Added: 
Tuesday, April 15, 2014


We have just released the RSS ASCAT winds (version 1) from the scatterometer on the MetOp-A satellite. They were created using the C-2013 Geophysical Model Function, which was carefully designed using a methodology consistent with that used for the QuikScat scatterometer. The ASCAT winds have excellent agreement with RSS Ku-2011 v4 QuikSCAT data and with RSS V7 microwave radiometer data.

Comparison of ASCAT to other wind data

The figure above shows a time series of wind speed differences for the C-2013 ASCAT as compared to the Ku-2011 QuikSCAT (red line), V7.01 WindSat (blue line), V7 F17 SSMIS (green line) and NCEP GDAS model winds (black line).  Note the greater difference with NCEP exists for several reasons that include the different temporal and spatial resolution of the model, the tri-linear interpolation process, model design and limitations, and the fact that these 10-m winds are not neutral winds. The ASCAT-NCEP difference increases after 2009 likely due to the loss of QuikSCAT data as input to the GDAS model. The F17 SSMIS wind speeds have a known minor drift of less than 0.1 m/s starting in 2010.  We have confirmed that the drift is in the F17 SSMIS data and not the ASCAT data.  The seasonal variation in the microwave radiometer data, both WindSat and F17 SSMIS is likely due to some geophysical atmospheric/surface effect that impacts radiometers but not scatterometers.

The RSS C-2013 ASCAT data set currently exists for June 2007 to June 2011.  We are working on extending the data set to the current time.  We are waiting for reprocessed input data from EUMETSAT before we release more data and slight improvements.  

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