West African Sahel has become wetter during the last 30 years, but dry spells are shorter and more frequent

ABSTRACT: Over the twentieth century, Sahel rainfall has undergone extreme variations on a decadal timescale. This study investigated the recent precipitation changes in West African Sahel using a high-resolution Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) product over the period 1981-2014. We found that the recent increase in precipitation results principally from an increase in the number of wet days (+10 d compared to the normal) over the entire West African Sahel band, along with an increase in the precipitation intensity over the central part of the West African Sahel (+3 mm d-1). However, this overall increase in precipitation is associated with dry spells that are becoming more frequent but on average shorter over the entire West African Sahel band (on average by 30%), and with precipitation intensity that is decreasing (around 3 mm d-1 during the study period) in the western part of the West African Sahel (Senegal). Such reorganization (i.e. weaker but more frequent precipitation) is expected to be beneficial for agriculture and society, reducing the likelihood of both flooding and droughts.