Interdecadal variations in persistent anomalous cold events over Asian mid-latitudes

Abstract

Based on the Japanese 55-year reanalysis daily data, this study finds that the frequency of persistent cold events from Lake Balkhash to Lake Baikal exhibits a clear interdecadal variation. Circulation characteristics, such as interdecadal variations in regional persistent cold event frequencies, are the focus of this study. During the 57-year period, a subperiod from the mid-1980s to the late 1990s exhibits inactive characteristics compared with those before and after during the study period. On a subseasonal timescale, the typical circulation patterns of persistent cold events are characterized by wave-train anomalies across the Atlantic Ocean and Eurasian continent, with significantly positive height anomalies that persist over the Ural Mountains in the upper troposphere, positive SLP anomalies over Eurasian mid- to high latitudes and cold SAT anomalies from Lake Balkhash to Lake Baikal. The changes in background circulation at the interdecadal timescale correspond well with the typical circulation patterns at the subseasonal timescale, indicating their important role in modulating the frequency of persistent cold events. Interdecadal changes in the background circulation can be partially explained by transient eddy feedback forcing.