Recent climatological trend of the Saharan Heat Low and its impact in West African climate

Abstract : The saharan Heat low (sHl) plays a crucial role in the West african Monsoon in spring and summer. the recent trend in sHl activity has been analysed using two sets of numerical weather prediction reanalysis. a local increase during the 90’s has been found in the two sets of temperature. this increase is stronger within the heat low region than the surrounding areas. this change is accompanied by a modification of the large scale and slow increase of temperature, but we do not observe a change in the filtered signal under 25 days. Despite a large variability of the temporal trends between 15 climate models from the CMip5 project, the trend is observed using the ensemble mean. nevertheless, the spatial and temporal evolutions of the Hl activities display a large difference between the reanalysis and climate models. the impacts and atmospheric variabilities have been compared in reanalysis and climate models and reveals different behaviours of the climate models to represent the west african monsoon interactions with Hl pulsations.