近百年东亚冬季气温及其大气环流变化型态

摘要

利用最新20世纪近百年再分析气象资料,研究近百年东亚冬季气温变化型及其相关的大气环流型态.结果表明近百年内东亚冬季气温主要有两种变化型:第一是东亚西南与东北相反气温变化型,表现在40°N以南及105°E以西地区(西南地区)气温变化与40°N以北及105°E以东地区(东北地区)变化相反；第二是40°N以南气温一致变化型.与第一种气温变化型耦合的大气模态是500hPa欧亚型遥相关、西伯利亚高压及北大西洋涛动.当欧亚型遥相关负位相,北大西洋涛动正位相及西伯利亚高压减弱时,有利于蒙古和我国105° E以东的区域增温而我国西南地区和青藏高原降温,反之亦然.第二种气温变化型耦合大气模态是500hPa西太平洋型遥相关,北太平洋涛动.当西太平洋型遥相关及北太平洋涛动处于正位相时(北太平洋北负南正),东亚40°N以南地区增温,东亚40°N以北地区降温.耦合的大气模态的型态差异,影响各阶段气温的年际变化.近一百年中,欧亚型遥相关和北大西洋涛动在1984～2010期间的型态最显著,是20世纪80年代东亚显著增暖的原因之一.研究还发现20世纪中期后东亚气温的年际变化与极地环流的变化联系紧密,表现在西伯利亚高压范围东扩并与极地环流联系,也是近百年气温趋势上升的一个原因.%Two patterns of winter temperature variability over East Asia and their association with the atmospheric circulation patterns for the last 100 years are documented based on the 20th century reanalysis datasets. In one pattern, the changes in temperature over the southwest of East Asia (south of 40°N and west of 105°E) are opposite to those over northeastern East Asia (north of 40°N and east of 105°E). The other pattern is characterized by consistent changes in temperature over East Asia south of 40°N. The Eurasian atmospheric circulation teleconnection pattern, the North Atlantic Oscillation (NAO), and the Siberian high are associated with the first type of East Asian temperature variability. The Eurasian pattern in a negative phase at 500 hPa, the NAO in a positive phase, and a weaker Siberian high are favorable for an increase in winter temperature over Mongolia and east of 105°E in China (Southwest China and the Tibetan Plateau), and vice versa. The western Pacific pattern (WP) at 500 hPa and the North Pacific Oscillation (NPO) correspond to the second type of East Asian temperature variability pattern. When WP and NPO were in a positive phase (negative values in the north and positive values in the south of the Pacific Ocean), the winter temperatures over the area south of 40°N in East Asia increased (decreased). The differences in the spatial pattern of the atmospheric modes can impact on the winter East Asian temperature interannual variability. During the last 100 years, the Eurasian pattern and the NAO were most notable during 1984-2010, contributing to the rapid warming over East Asia after the 1980s. We also found that the correlation between the East Asian winter temperature variability and polar circulation has increased since the middle of the 20th century and that the eastward extending Siberian high has a strong link to the polar circulation, which could also be responsible for the warming over East Asia during the last 100 years.