Application of the NCAR regional climate model to eastern Africa 1. Simulation of the short rains of 1988
Date
1999Author
Sun, L Q
Semazzi, Fredrick H M
Giorgi, Filippo
Ogallo, Laban
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
The National Center for Atmospheric Research (NCAR) Regional Climate
Model (RegCM2) is employed to investigate the physical mechanisms that govern the
October-December rains over eastern Africa. The model employs the Mercator conformal
projection, with a domain of 5580 km X 5040 km centered at 31°E, 4°S, and a horizontal
grid point spacing of 60 km. The simulation period is October-December 1988, and the
model initial and lateral boundary conditions are taken from ECMWF reanalysis. A
number of month-long simulations have been conducted to optimize various
parameterizations of the model which include the following factors: cumulus convection,
moisture parameterization, radiative transfer formulation, surface processes, boundary
layer physics, and the lateral boundary conditions. The model was successfully customized
over eastern Africa. The model simulates the large-scale circulation characteristics over
the region as well as local features such as the dominant precipitation maxima, the
Turkana low-level jet, and the diurnal reversal in the lake/land breeze circulation over
Lake Victoria. Several model deficiencies are also identified. They include a negative
rainfall bias over the western portions of the domain and the Kenya Highlands and a
temperature bias over the tropical forest regions. Systematic analysis of surface water
budget reveals that evapo-transpiration is a major sink in the water budget over the regions
where precipitation is moderate or small, while the role of runoff and drainage becomes
important over the regions where precipitation is abundant. The model simulations also
suggest that during the short-rains season, the large-scale circulation anomalies play the
most important role in shaping ,the precipitation anomalies.
URI
http://onlinelibrary.wiley.com/doi/10.1029/1998JD200051/abstracthttp://opensky.library.ucar.edu/collections/OSGC-000-000-013-548
http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/38520
Citation
Journal of Geophysical Research, Vol.104, No. 06, pages 6529-6548, March 27,1999Publisher
Department of Meteorology, University of Nairobi