Linkages of surface air temperature variations over Central Asia with large-scale climate patterns

Abstract

In this study, we investigate the dominant modes of surface air temperature variations of the cold season (from November through to the next March) and the warm season (from May to September) over Central Asia, and their associations with large-scale climate patterns for the period of 1979–2016. The first two modes of the cold season surface air temperature (CSAT) over Central Asia, obtained by empirical orthogonal function (EOF) analysis, feature the monopole structure and the north-south dipole pattern, respectively. For the warm season surface air temperature (WSAT), the leading two EOF modes are characterized by the homogenous structure and the northwest-southeast seesaw pattern, respectively. Further analysis indicates that the large-scale atmospheric circulation anomalies play key roles in the CSAT and WSAT variations over Central Asia. The CSAT variation over Central Asia is closely related to the Scandinavia pattern (SCAND) and the Arctic Oscillation (AO), while the WSAT variation is tightly tied to the East Atlantic/Western Russia pattern (EAWR) and the North Atlantic Oscillation (NAO). These large-scale climate patterns tend to cause the CSAT and WSAT anomalies over Central Asia via their effects on regional geopotential heights, warming advections, and other processes. Positive geopotential height anomalies and increased downward solar radiations generally favor positive SAT anomalies over Central Asia. Moreover, the warm advections are also conducive to the formation of positive SAT anomalies over Central Asia. Our findings are expected to facilitate the improvement of understanding and predicting the CSAT and WSAT variations over Central Asia.