Dr Wim Verkley, KNMI

will speak on

Manually adjusting a numerical weather analysis: Application to a case of rapid cyclogenesis

Time: 2:15PM
Date: Thu 8th March 2007
Location: Mathematical Sciences Seminar Room [map]

Further information

Abstract: We will discuss a method by means of which a numerical weather
analysis can be modified by changing the potential vorticity field
of the analysis. The method is meant to be of use operationally, but
can also be applied to the study of weather phenomena such as rapid
cyclogenesis. The onset of rapid cyclogenesis has a clear signature
in water vapour satellite imagery. Due to a relationship between
potential vorticity and brightness temperature in the water vapour
absorption channel, it is sometimes possible to judge whether or not
a numerical weather analysis is on the right track in predicting its
future development. We will discuss a case in which the Dutch
version of HIRLAM (HIgh Resolution Limited Area Model) displayed
in its analysis a rather clear mismatch between water vapour
satellite imagery and potential vorticity in the beginning phase
of rapid cyclogenesis. HIRLAM underestimated the development
of the cyclone that ended up at the west coast of Ireland in the
afternoon of 7 November 2005. Our method is used to investigate
the effect of local shifts of the jet stream on the development
of the cyclone.

(This talk is part of the Meteorology series.)

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