Influence of slab-ocean parametrization in a regional climate model
(RegCM4) over Central Africa
Abstract
The study aims to assess the local response of the regional climate
model version 4.6 (RegCM4.6) to the coupling of ocean-atmosphere
interaction in Central Africa. The ability of the model is evaluated
over six years (first January 2001, to thirty-first December 2006) by
conducting two different experiments with the Grell convective scheme.
The experiments are carried out monthly with a spatial resolution of 40
km. The model was forced by ERA-Interim reanalyses and validated by GPCP
(Global Precipitation Climatology Project) observational data, ERA 5 and
ERA-Interim reanalyses. To evaluate the influence of the slab-ocean, we
carried out two different experiments: The first experiment is designed
to produce the climatology and force the surface limits of RegCM with
the sea surface temperature. The second experiment is designed to couple
RegCM with the slab-ocean, which provides mutual interaction between the
ocean and the atmosphere. Using statistical tools, we evaluated the
model’s ability to simulate precipitation, surface temperature and wind.
Both experiments reasonably reproduce the main characteristics of the
rainfall regime, temperature and wind. A comparative analysis of the
different experiments reveals that the performances of the experiments
are similar in Central Africa and in the different homogeneous
sub-regions as far as rainfall is concerned, but there are subtle
differences. Slab-ocean improvement varies from season to season and
from the sub-region to sub-region. However, we note a significant
improvement in temperature and rainfall over the Indian Ocean.