Dominant patterns of winter surface air temperature over Central Asia and their connection with atmospheric circulation

The dominant patterns of the winter (December-February) surface air temperature anomalies (SATAs) over Cen-tral Asia (CA) are investigated in this study. The first two leading modes revealed by empirical orthogonal function (EOF) analysis represent the patterns by explaining 74% of the total variance. The positive phase of EOF1 is char-acterized by a monopole pattern, corresponding to cold SATAs over CA, while the positive phase of EOF2 shows a meridional dipole pattern with warm and cold SATAs over northern and southern CA. EOF1 is mainly modulated by the negative phase of the Arctic Oscillation (AO) in the troposphere, and the negative AO phase may be caused by the downward propagation of the precursory anomalies of the stratospheric polar vortex. EOF2 is mainly in-fluenced by the Ural blocking pattern and the winter North Atlantic Oscillation (NAO). The SATAs associated with EOF2 can be attributed to a dipole-like pattern of geopotential height anomalies over CA. The dipole-like pattern is mainly caused by the Ural blocking pattern, and the NAO can also contribute to the northern part of the dipole.

Automated summary

This study investigates the dominant patterns of winter surface air temperature anomalies over Central Asia. It identifies a cold monopole pattern and a warm-cold meridional dipole pattern as the dominant modes. The cold pattern is mainly influenced by the negative phase of the Arctic Oscillation, while the dipole pattern is primarily caused by the Ural blocking pattern and winter North Atlantic Oscillation.