双月刊

ISSN 1006-9895

CN 11-1768/O4

1980-2019年中亚夏季地表气温的异常增暖
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1.浙江大学地球科学系;2.浙江大学地球科学学院;3.浙江省气象科学研究所(中国气象科学研究院浙江分院)

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42075050


The abnormal warming of summer surface temperature in Central Asia from 1980 to 2019JIA Xiaojing1, Liu Xuke1 and QIAN Qifeng2
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    摘要:

    本文利用1980-2019年NCEP/NCAR全球再分析资料、CRU地表气温资料、积雪覆盖率资料和全球海温资料,分析了中亚夏季地表气温的气候突变及其和北大西洋海温、青藏高原积雪之间的关系。结果表明:中亚夏季地表气温在2005年发生明显的气候突变。标准化的中亚区域平均的气温指数从之前的负位相为主变为之后的正位相为主,表示中亚地区夏季地表气温显著增温。和中亚夏季地表气温异常增温相联系的大气环流场的分析表明,2005年之后,中亚地区西侧的反气旋性环流系统异常增强,该反气旋异常对应的大气下沉增暖以及反气旋异常增强引起的云量减少进而导致向下的短波辐射增加均有利于中亚夏季气温异常升高。进一步的合成分析表明,中亚夏季地表气温在2005年的气候突变和北大西洋中高纬度地区的海表温度的增暖和青藏高原西部积雪的减少有着密切关系。北大西洋中高纬度海表温度增温能激发一个向下游传播的罗斯贝波,青藏高原西部积雪减少能够通过积雪的反照率效应对上空的大气有增温作用,两者均能增强中亚地区上空的反气旋系统,从而有利于中亚夏季地表气温异常偏高。

    Abstract:

    Based on NCEP / NCAR reanalysis data, CRU surface air temperature (SAT), snow cover and global sea surface temperature (SST) data from 1980 to 2019, the current work analyzes the abrupt change of summer SAT in Central Asia (CA) and its relationship with SST in the North Atlantic and snow cover in the Qinghai Tibet Plateau. The results show that the summer SAT in CA experiences significant climate shift at 2005. The standardized regional average temperature index in CA shifts from the previous negative phase to the subsequent positive phase, indicating that the summer SAT in CA has increased significantly. The analysis of the anomalous atmospheric circulations related to the interdecadal changes of summer SAT in CA shows that after 2005, the anticyclonic circulation system in the west of CA is abnormally enhanced. The atmospheric subsidence associated with the anomalous anticyclone can cause warming. Meanwhile, the reduction of cloud amount caused by the enhancement of this anticyclone anomaly leads to the increase of downward short wave radiation and therefore is favorable for increase of summer temperature in CA. Further analysis shows that the interdecadal changes of summer SAT in CA at 2005 is closely related to the warming of SST in the middle and high latitudes of the North Atlantic and the reduction of snow cover in the west of the Tibet Plateau (TP). The increase of SST in the middle and high latitudes of the North Atlantic can stimulate a Rossby wave propagating downstream. The reduction of snow cover in the west of the TP can cause warming to the above atmosphere through the albedo effect of snow. The changes of both the North Atlantic SST and the TP snow can strengthen the anticyclone over CA, resulting in an abnormally high summer SAT over there.

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  • 收稿日期:2022-03-25
  • 最后修改日期:2022-06-15
  • 录用日期:2022-08-01
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