Abstract:
The latest version of RegCM4 with CLM4.5 as a land surface scheme was used to assess the performance
and sensitivity of the simulated West African climate system to different convection schemes. The
sensitivity studies were performed over the West African domain from November 2002 to December 2004 at a
spatial resolution of 50 km×50 km and involved five convective schemes: (i) Emanuel; (ii) Grell; (iii) Emanuel
over land and Grell over ocean (Mix1); (iv) Grell over land and Emanuel over ocean (Mix2); and (v) Tiedtke. All
simulations were forced with ERA-Interim data. Validation of surface temperature at 2m and precipitation were
conducted using data from the Climate Research Unit (CRU), Global Precipitation Climatology Project (GPCP)
and the Tropical Rainfall Measurement Mission (TRMM) during June to September (rainy season), while the
simulated atmospheric dynamic was compared to ERA-Interim data. It is worth noting that the few previous
similar sensitivity studies conducted in the region were performed using BATS as a land surface scheme and
involved less convective schemes. Compared with the previous version of RegCM, RegCM4-CLM also shows a
general cold bias over West Africa whatever the convective scheme used. This cold bias is more reduced when
using the Emanuel convective scheme. In terms of precipitation, the dominant feature in model simulations is a
dry bias that is better reduced when using the Emanuel convective scheme. Considering the good performance
with respect to a quantitative evaluation of the temperature and precipitation simulations over the entire West
African domain and its subregions, the Emanuel convective scheme is recommended for the study of the West
African climate system.
