This page provides monitoring information on a monthly basis concerning the product
calibration for the near-real time 25 km ASCAT winds on Metop-A, Metop-B and Metop-C.
Mean monthly values of selected parameters are plotted as a function of time. The wind
speed bias is computed against the wind forcasts of the operational ECMWF Numerical
Weather Prediction model. For the NWP Ocean Calibration residuals, a separate plot is
shown for each antenna. The user may choose to view the plots of the last year (here below)
or the long term plots since 2013 (further below, click here).
For the Cone Metrics residuals, a plot of the residuals of last month is shown below
Residuals are calculated against a reference, for which ASCAT-B data of 2013 is chosen.
Other than NWP Ocean Calibration, Cone Metrics relies only on backscatter data, and does
not depend on ECMWF winds and GMF. The advantage is that any anomaly seen by Cone Metrics
can be attributed to an instrumental cause.
The monitoring of relevant quality parameters as a function of time yields a sensitive
method of detecting deviations of normal operation. Deviations in product quality usually
appear as a step in one or more of the plots. It can be checked if they are connected to
an update of the wind product in the 'Modifications/anomalies' section on the main page
of the specific product viewer (see links on the right hand side).
The NWP Ocean Calibration method is described in:
Verspeek, J., A. Stoffelen, A. Verhoef and M. Portabella,
Improved ASCAT Wind Retrieval Using NWP Ocean Calibration IEEE Transactions on Geoscience and Remote Sensing, 2012, 50, 7, 2488-2494,
The Cone Metrics method is described in:
Belmonte Rivas, M., A. Stoffelen, J. Verspeek, A. Verhoef, X. Neyt and C. Anderson,
Cone Metrics: A New Tool for the Intercomparison of Scatterometer Records IEEE Journal of Selected Topics in Applied Earth Observations and
Remote Sensing, 2017, 10, 5, 2195-2204,