Simulation of radar reflectivities using Hirlam forecasts
Günther Haase and Carl Fortelius
Abstract
The three-dimensional radar simulation model (RSM) developed at the
University of Bonn in cooperation with the German Weather Service (Haase
and Crewell, 2000) has been implemented at the
Finnish Meteorological Institute (FMI). Using predicted hydrometeors and
state variables from the High Resolution Limited Area Model (Hirlam), the
RSM is able to simulate radar reflectivity measurements of any weather
radar situated within the model domain. The RSM is expected to be useful
for (a) the validation, and hence improvement of mesoscale models, (b)
monitoring model forecasts in real time by comparing simulated radar images
to real ones, and (c) estimating some of the errors related to the
retrieval of the surface rain rate from radar reflectivity measurements. In
the future the RSM might be used in the context of the variational
assimilation of radar reflectivity observations. In this report we present
the RSM model, its installation and its use as an independent post
processing device to the Hirlam system. In addition we present briefly two
case studies, in which we compare simulated and real measurements for a
C-band radar in southern Finland. The purpose is not to draw general
conclusions about the RSM itself, nor indeed about the Hirlam system, but
to give examples of how the technique might be used in more extensive
studies.
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