Contribution From the Occurrence and Intensity of Wet Days to the West African Rainfall Variability in CMIP6 Models

Abstract We analyze the relationship between total precipitation change and change in occurrence and intensity of wet days across West Africa using simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6). While both changes in the intensity and occurrence of wet days contribute to the projected decrease of total precipitation over the West Sahel, there is a larger contribution from changes in the number of wet days, associated with a shorter precipitation season. The projected increase of total precipitation over the Central‐Eastern Sahel is connected primarily with changes in the intensity of wet days. Over the Guinean Coast, models disagree in how total precipitation will change, since they tend to show a decrease in the number of wet days combined with an increase in intensity of wet days. Evaluation of the models during the historical period shows they do not reproduce several key features of the observed relationships.