Factors responsible for the increase of winter low temperature extremes from the mid-1990s to the early 2010s in northern china

Abstract

It is argued that the occurrence of cold events decreases under the background of global warming. However, from the mid-1990s to the early 2010s northern China experienced a period of increasing occurrence of low temperature extremes (LTE). Factors responsible for this increase of LTE are investigated in this analysis. The results show that the interdecadal variation of the winter mean temperature over the middle and high latitude Eurasia acts as an important thermal background. It is characterized by such two dominant modes as the “consistent cooling” pattern and the “Warm high latitude Eurasia and cold middle latitude Eurasia” pattern from the mid-1990s to the early 2010s. And the two patterns jointly provide a cooling background for the increase of LTE in northern China. Meanwhile, though the interdecadal variation of Arctic oscillation (AO), Ural blocking (UB) and Siberian high (SH) are all highly correlated to the occurrence of LTE in northern China, the AO is found to play a dominant role. On one hand, the AO affects directly the occurrence of LTE for its dynamic structure; on the other hand, it takes an indirect effect by affecting the intensity of Ural blocking (UB) and Siberian high (SH). Further analyses show that, the winter temperature over the middle and high latitude Eurasia has a close relationship with the AO, but they are believed to be the independent influential factors of the increase of LTE in northern China from the mid-1990s to the early 2010s.