Updated @ 2021-01-17 22:24 utc
OSI SAF ASCAT-A 25-km monitoring
|Data from last 7 days|
DescriptionThis page provides monitoring information in near-real time concerning the wind product. Mean values of selected parameters are plotted as a function of time. The monitoring results of different parts of the satellite swath, corresponding to different across track locations or Wind Vector Cell (WVC) numbers, are plotted in different colours. The user may choose to view the data of the last seven days or the information of the previous quarter (daily averages) by clicking on the link on the right hand side.
The Maximum Likelihood Estimator (MLE) is a normalised measure of the minimum distance between the measurements and the Geophysical Model Function (GMF) surface (i.e. MLE of first-rank wind solution). It provides a good indication of the quality of the wind retrieval. Scatterometer winds are also compared with NWP model winds and information considering the timeliness of the wind production is provided.
The monitoring of relevant quality parameters as a function of time yields a sensitive method of detecting deviations of normal operation. However, one must be careful to regard the difference with reference background NWP model winds as the 'true' accuracy of the product, since both the NWP model winds and the scatterometer winds contain errors. 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 this product viewer. Updates of the ECMWF model are reported on the ECMWF website.
The incoming data at KNMI are processed into a wind product within 10 minutes. The end to end timeliness is measured from the end of satellite data acquisition until the availability of the wind product for the end user. Although this timeliness is to a great extent out of the scope and control of KNMI, it is of interest to the end users to have knowledge about the data age at the time of reception.
KNMI hosts the operational deployment of this product as part of the EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF), see related link or click on the OSI SAF logo above for more information.