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Chapter IV: Interactive Overlays

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Interactive Overlays

In this chapter you can make your own overlays for the last six ASCAT passes of this case study (between midday 26th February and 1st March). For all passes you can overlay ASCAT wind fields with MSG images - IR10.8, WV6.2 and Air Mass RGB. For the passes on 26th February (both at midday and at the end of the day) and on 1st March over the Baltic, there is also the possibility to overlay the closest analysis and forecasts of relevant NWP fields. Isobars are plotted every 5 hPa and isotachs are plotted every 5 kt for wind speeds larger than 30 kt.

The following questions/guidelines may help you in this task - for simplicity, the instants correspond to the MSG images closest to the ASCAT observations.

A) 26/02/2010 - 12:30 UTC

Find Xynthia in the North Atlantic using MSG images and ASCAT in sequence. Then see how the analysis fits both kinds of observations. Afterwards, analyse how the forecasts evolved with time. Forecasts and analysis are both for 12 UTC on 26th February.

B) 26/02/2010 - 22:00 UTC

Overlay ASCAT wind with ECMWF 10m wind fields from analysis and forecasts; then analyse regions of higher wind speed in the North Atlantic and relate them to MSG images and other analysis parameters. Forecast fields are valid for 21 UTC on 26th and analysis fields for 00 UTC on 27th February.

C) 27/02/2010 - 10:15 UTC

Identify how many depressions were affecting the North Atlantic and Europe together with Xynthia and compare the surface wind information that can be taken from ASCAT for each depression.

D) 27/02/2010 - 21:45 UTC

Look at the MSG Airmass RGB image in combination with ASCAT and describe the feature in the Bay of Biscay.

E) 28/02/2010 - 19:45 UTC

Compare ASCAT wind patterns for Xynthia over the North Sea with ASCAT wind speed patterns in the Baltic Sea, the Mediterranean and off the northern coast of Norway; analyse the corresponding MSG images.

F) 01/03/2010 - 09:30 UTC

Check the changes in consecutive forecasts of, for instance, mean sea level pressure and compare them to ASCAT wind observations for a measure of model uncertainty. Forecast fields are valid for 9 UTC and analysis fields for 12 UTC on 1st March.