Application of the NCAR regional climate model to eastern Africa: 1. Simulation of the short rains of 1988
Article first published online: 21 SEP 2012
Copyright 1999 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 104, Issue D6, pages 6529–6548, 27 March 1999
How to Cite
1999), Application of the NCAR regional climate model to eastern Africa: 1. Simulation of the short rains of 1988, J. Geophys. Res., 104(D6), 6529–6548, doi:10.1029/1998JD200051., , , and (
- Issue published online: 21 SEP 2012
- Article first published online: 21 SEP 2012
- Manuscript Accepted: 9 OCT 1998
- Manuscript Received: 4 FEB 1998
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 conformai projection, with a domain of 5580 km × 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 evapotranspiration 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.