1~3月鄂霍次克海海冰对我国冬春季气温的可能影响

Possible Influence of Jan.-Mar. Sea Ice over the Sea of Okhotsk on Air Temperature in China

本文利用Hadley气候预报中心提供的海冰浓度数据(SIC),分析了1979~2018年共40年1~3月鄂霍次克海海冰浓度时间变化特征及分布特征;利用NCEP/NCAR再分析资料提供的近地面温度数据和环流场数据,分析了1~3月中国气温变化特征;使用相关分析方法讨论1~3月鄂霍次克海冰异常与同期及后期中国气温的关系;使用合成分析方法讨论1~3月海冰异常与大气环流的关系。得出以下结论:近40年1~3月中国气温总体上呈增温状态,增温幅度最大在青藏高原地区。总体来看,冬季海冰变化与3~5月中国气温相关性较好。1~3月鄂霍次克海海冰偏多时,阿留申低压加深,500 hPa上极涡减弱,欧亚大陆中高纬存在异常气旋性环流,经向活动增强,引导极涡南下,配合贝加尔湖地区横槽及其上游乌拉尔山地区的阻塞高压存在,表现为经典寒潮形式,加强冷空气自西向东向中国的输送,造成中国北方地区同期及后期温度偏低。海冰偏少时,情况基本相反。

Based on the Sea Ice Concentration (SIC) provided by Hadley Climate Prediction Center, the tem-poral variation and distribution characteristics of Sea Ice Concentration in the sea of Okhotsk in January-March during the time period from 1979 to 2018 are analyzed. Based on near-surface temperature data and circulation field data provided by NCEP/NCAR reanalysis data, the charac-teristics of air temperature change in January-March in China are also analyzed in the thesis. The correlation between JFM Sea Ice anomaly over Okhotsk in January-March and air temperature in China during the same period and in the later period is discussed by correlation analysis method. The correlation between winter Sea Ice anomaly and atmospheric circulation in January-March is discussed by synthetic analysis method. The main conclusions of this paper are as follows: In the past 40 years, the winter temperatures all over the China are increasing, with the largest over Tibet Plateau. Overall, the JFM Sea Ice has significant correlation with the temperature in China in the Mar.-May. In the Mar.-May, when the Sea Ice in Okhotsk is abnormally heavy, the Aleutian low deepened;the 500 hPa upper polar eddy weakened;the abnormal cyclonic circulation existed in the middle and high latitudes of Eurasia continent, and the meridional activity increased, leading the polar eddy to the south, cooperating with the existence of the transverse trough in Lake Baikal and the blocking high in the Ural Mountains upstream of the region, which showed the classical circulation pattern of cold wave and enhanced the transmission of cold air from west to east to China. The temperature in the northern part of China was low during the same period and later. When the sea ice is too small, the situation is basically the opposite.