2018/2019年冬季北半球大气环流特征及对我国冬季气温异常的影响

Northern Hemisphere Atmospheric Circulation Characteristics in Winter 2018/2019 and Its Impact on Temperature Anomalies in China

2018/2019年冬季,东亚冬季风较常年同期偏强,西伯利亚高压偏强。在北半球500 hPa高度距平场上,乌拉尔山地区为高度场正异常,贝加尔湖-巴尔喀什湖地区为高度场负异常,欧亚中高纬整体以经向型环流为主。冬季冷空气活动较频繁且强度偏强,受其影响,除东北地区、西南地区及华南地区中东部等地气温较常年同期偏高外,全国其余地区气温偏低。此外,欧亚中高纬环流季节内调整明显,导致我国气温异常表现出明显的阶段性特征。前期秋季巴伦支海-喀拉海海冰密集度偏低是造成东亚冬季风偏强的重要原因。

The East Asian winter monsoon and the Siberian high were both stronger than normal during the2018/2019 winter. For geopotential height anomalies at 500 hPa in Northern Hemisphere, the Ural Mountain Area was positive anomaly, and Baikal Lake-Barkash Lake Area was negative anomaly. The mid-high latitudes of Eurasia were mainly dominated by meridional circulation. In winter 2018/2019, the cold air processes occurred frequently and the intensity was strong. The temperature in the northeastern, southwestern and central and eastern parts of South China were higher than normal, but the other parts were on the low side due to the influence of the cold air processes. In addition, the intraseasonal variation of circulation of the mid-high latitudes of Eurasia was significant, which leads to the periodic characteristics of temperature anomaly in China. The lower concentration of sea ice in the Barents Sea and Kara Sea in the early autumn is the main reason for the strong East Asian winter monsoon.