Atlantic and Mediterranean-Sourced Precipitation over the Maghreb: Trends and Spatiotemporal Variability

The Mediterranean basin is recognized as a potential focal point of global warming, marked by a rising incidence of both droughts and floods. Nevertheless, uncertainties persist regarding the precise impact of climate change on the water cycle in this region. Therefore, this study endeavors to scrutinize the recent precipitation trends and fluctuations across the Maghreb (Morocco, Algeria, and Tunisia) and their connection to both the Atlantic and Mediterranean moisture sources. To spatialize these trends and variations, we used a satellite precipitation product that we have beforehand evaluated at different time scales. Furthermore, we employed two influential teleconnection patterns: the NAO index, representing Atlantic influence, and the WeMO index for theMediterranean influenceThe statistical assesment of the satellite-based rainfall data demonstrated strong correlations with ground-based rainfall, ranging from 0.45 to 0.8. The median Percentage Bias was found to be 10%. The median Mean Absolute Error was approximately 12 mm, while the Root Mean Square Error averaged around 18 mm. Overall, all chosen criteria yielded satisfactory outcomes, providing a suitable level of confidence for conducting spatio-temporal trend analysis at the pixel level. At temporal scale, the trend results showed some upward trends in precipitation in certain areas during the months of March, April, August, September, and October. However, for the remainder of the year, the dominant trend is a decrease in precipitation across most of the North African territories. At spatial scale, the findings unveiled a decline in precipitation levels in the central and southern regions, while showcasing an increase in precipitation across the northern Maghreb. Moreover, the sphere of influence exerted by the WeMO exhibited expansion, along with a notable amplification in its modulation of precipitation patterns, particularly from September to April. Conversely, the NAO exerted a more pronounced influence during the winter months.