Shallow circulation, advective drying and inter-annual variability of Sahel precipitation in present and future climate

Effects of local land surface heating and global convection on Sahel precipitation are examined by applying a novel moisture budget analysis methodology to present day and future (rcp4.5) CCSM4 simulations. Net precipitation over the Sahel is found to be a result of a competition between heat-low driven moistening and global convection driven advective drying. With a correlation of 0.88, much of the inter-annual variation in simulated Sahel precipitation can be explained by the shallow moistening. While drying associated with advection by global circulation has lower negative correlation of -0.44 with the net precipitation. This relationship of precipitation with local and global forcings carries over with 21st century simulation as well.