The Role of Moisture Scheme in Regional Climate Modelling of Precipitation over the Horn of Africa
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Date
2011-06
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Addis Ababa University
Abstract
This study aims to improve the capability of the latest Regional Climate Model version
4 (RegCM4) to simulate the precipitation over the Horn of Africa. Although there are
several aspects in which the model can be improved, the focus of this study is to tackle
the problem of its moisture scheme. RegCM4 moisture scheme has fourteen moisture
scheme parameters, which can be tuned within the allowed physical limits. Each of the
14 moisture parameters have been varied around the current default setting and over 80
model runs have been performed, for a domain de ned by 60km resolution, 18 vertical
levels covering nearly the whole Africa geographycally and major circulation patterns
that derive climate over the region. We have found physical sound set of parameters
to be used in the fourteen moisture scheme parameters that have sigini cantly reduced
bias in RegCM4 pricipitation; improved correlation of RegCM4 precipitation with respect
GPCP and CMAP; and captured seasonal and interannual variations over most of the 12
delineated homogeneous regions of Horn of Africa
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Keywords
Precipitation over the Horn of Africa