Influence of Soil Moisture Anomaly on Temperature in the Sahel: A Comparison between Wet and Dry Decades

Abstract

The influence of the Sahelian drought and resultant soil moisture deficit on air temperature is explored, using a simple water balance model that was validated with multiyear observations of the root-zone soil moisture. A comparison between wet soil years in the 1950s to 1960s and dry soil years in the 1970s to 1980s demonstrated a series of processes by which precipitation anomalies during the rainy season of a few months influence the time-lagging temperature through soil moisture. These processes were clearly seen only during the beginning 1 or 2 months of the dry season, and then both the concurrent soil moisture and temperature anomalies disappeared. Thus, the timescale of the drying up of root-zone soil moisture anomalies was determined to be approximately 1.5 months. This suggests that the root-zone soil moisture does not act as a memory of rainfall anomaly into the following rainy season and is not related to the long-term persistence of the drought.