Characterizing variability of spatial patterns of annual and seasonal precipitation of Turkey and identifying the probable driving factors including teleconnection patterns

This study aims to delve into the spatial modes of Turkish precipitation variability using a rotated empirical orthogonal function (EOF) method and describe the resulting variability patterns in association with atmospheric and non-atmospheric influences. The varimax rotation of the EOF determines modes that are more localized in space than the conventional EOF modes. The primary modes of the annual, wet season, and dry season precipitation from 213 stations for the 1975-2021 period were extracted and described concerning atmospheric processes, prominent teleconnection patterns, orography, and continentality. The first three EOFs accounted for approximately 67 and 62% of the total variance in the annual and wet season precipitation series, respectively, whereas only 50% of the variance was captured by the first three EOFs for dry season precipitation. The spatial coherence of the highest negative and positive EOF1 loadings of the annual data was observed in the western, southern, and north-eastern regions. The contribution of atmospheric moisture advection in precipitation variability diminishes in summer, whereas the role of local land surface processes increases. Some regional teleconnection patterns, such as Arctic oscillation (AO) and North Atlantic oscillation (NAO), also contributed to the annual variability in precipitation.