Abstract:
This modeling study is conducted to examine the potential impact of the reforestation (greenbelt) location (either in Sahel or in
Guinean region) on West African summer climate system. To this end, three simulations using the regional climate model
RegCM4 driven by ERA-Interim reanalysis were performed at 50 km horizontal resolution over a West African domain for
the period 2000–2011. The first experiment, namely the control (CTRL), uses the standard vegetation cover, while the two others
incorporate throughout the model integration, a zonal reforestation band of evergreen broadleaf over different locations: (i) over a
13° N–17° N band latitudes in a Sahel-Sahara region (experiment hereafter referred to as GB15N) and (ii) between 8.5° N–11.5°
N in the Guinea Coast region (experiment hereafter referred to as GB10N). A comparison of the CTRL experiment with
observation reveals a faithful reproduction of the mean boreal and summer seasonal precipitation pattern, though substantial
dry/wet biases remain, especially in the Atlantic Ocean. In addition, the seasonal cycle over sub-regions matches satisfactory the
observed pattern. The GB15N reforestation leads to a precipitation increase in the range of 2–4 mm/day over the forested areas,
whereas in the GB10N reforestation, precipitation increase is weaker and not necessarily located in the forested areas.
Temperature cooling is observed over the reforested area and may be explained by a decrease of ground heat flux related to a
reduction of the surface albedo.
