Influence of atmospheric and oceanic circulation patterns on precipitation variability in North Africa with a focus on Morocco.

There is growing demand for increased accuracy in sub-seasonal weather forecast. This calls for understanding of characteristics of precipitation variability in association with global teleconnections. This study analyzes the influence of major global teleconnections on spatial and temporal variability of precipitation in Morocco in the wet season over the period 1980-2015. We consider a suite of climate indices (CIs), including the North Atlantic Oscillation (NAO), various forms of the El Niño-Southern Oscillation (ENSO), the East Atlantic Oscillation (EA), the Mediterranean Oscillation (MO), and the Western Mediterranean Oscillation (WeMO). In addition, we analyze the Pacific Decadal Oscillation (PDO), the Atlantic Multidecadal Oscillation (AMO), the Scandinavian (SCAND) pattern, and the East Atlantic/Western Russia (EATL/WRUS) pattern. We identify the dominant teleconnections and examine their seasonal and regional impacts across Morocco using regression analyses, empirical orthogonal function (EOF) analysis, and wavelet coherence. Linear regression of sea surface temperature (SST) and geopotential height fields onto three identified precipitation zones reveals varying patterns of oceanic and atmospheric variability, with significant differences between winter and spring. Additionally, regressing precipitation against natural climate variability modes (CIs) indicates a complex interplay of global teleconnections. The NAO and MO emerge as the primary drivers of winter precipitation, whereas spring precipitation is more strongly modulated by the EA pattern and the WeMO. Secondary patterns such as SCAND and EATL/WRUS also exert region-specific influences. Notably, the influence of ENSO on precipitation evolved over the study period. ENSO-related impacts have strengthened post 2000, coinciding with enhanced Pacific-Atlantic coupling. Wavelet coherence analysis reveals that since 2000, Pacific signals (ENSO/PDO) have become more in phase with Atlantic variability (NAO/AMO), amplifying their effect on precipitation. These findings clarify the seasonal and regional teleconnection dynamics governing precipitation in Morocco and highlight an emerging influence of Pacific climate variability in the twenty-first century. This improved understanding can inform seasonal forecasting to support climate adaptation efforts in North Africa.