On the Atlantic Multidecadal variability role on modulating Mediterranean impact on Sahelian rainfall

Warm events in the Mediterranean basin are associated with increased Sahelian rainfall mainly due to enhanced moisture transport across the Sahara desert. Nevertheless, Mediterranean teleconnections with the Sahel have changed throughout the 20th century showing a nonstationary behaviour, with periods in which the teleconnection is enhanced. The impacts of the Mediterranean in the Sahel appear to have recently intensified being a key factor in the recovery trend after the severe drought experienced in the 1970s. The changes in the interannual co-variability patterns could be the result of counteracting effects due to remote teleconnections or to changes in the underlying climatology. In this study, the S4CAST model has been applied to assess Mediterranean-Sahel teleconnection from observational statistical analysis. Evidence of the aforementioned nonstationary link is provided. The inferred hypothesis obtained from observations are tested performing AGCM simulations with a general circulation model with the aim of exploring the role of the low frequency variability of the Atlantic on the recently enhanced Mediterranean impacts on Sahelian rainfall. The results suggest a modulation by different patterns of Atlantic low-frequency SST variability