青藏高原雪灾是该地区破坏力最大的气象灾害, 其变化成因一直备受关注。利用青藏高原72个台站逐日积雪资料及Hadley中心海温月平均资料, 采用广义平衡反馈分析与主成分分析相结合的最优反馈模分析方法, 研究了青藏高原雪灾频数对关键区海温异常模态的响应关系, 探讨了海温异常对雪灾频数的贡献度及产生的可能机制。结果表明: 青藏高原雪灾频数对赤道中东太平洋海温异常的El Ni?o型模态和热带印度洋海温偶极子模态响应显著, 两个模态对雪灾频数的贡献为45.9%。雪灾频数对海温异常的响应主要通过与之相联系的大气环流异常实现, 热带太平洋第一模态(TP1)海温强迫时, 500 hPa高度场上亚欧大陆中高纬自西到东呈现“+-+”形势, 形成典型的两脊一槽型; 热带印度洋第二模态(TI2)强迫时, 主要引起中低层水汽异常, 阿拉伯海暖湿气流进入高原南部, 西北太平洋湿润气流进入高原北部, 为降雪提供了水汽条件, 在此高低层配置下易出现多雪灾年。
The snow disaster over the Qinghai-Xizang Plateau is the most destructive meteorological disaster in the region, and the causes of its changes have been receiving much attention.In this paper, the daily snow cover data of 72 stations over the Qinghai-Xizang Plateau and the monthly mean sea surface temperature data of the Hadley Center were used, and the optimal feedback mode analysis method combining generalized balanced feedback analysis with principal component analysis (GEFA-EOF) was adopted.We studied the response relationship between the frequency of snow disasters in the Qinghai-Xizang Plateau and the modes of SST anomalies in critical areas, and discussed the contribution of SST anomalies to the frequency of snow disasters and the possible mechanism of their occurrence.The results show that the frequency of snow disasters over the Qinghai-Xizang Plateau responds significantly to the El-Ni?o mode (TP1) and the tropical Indian Ocean temperature dipole mode (TI2) in the equatorial Middle East Pacific Ocean SST anomalies.The contribution of the two modes to the frequency of snow disaster is 45.9%.The response of the snow disaster frequency to the sea temperature anomaly is mainly realized through the atmospheric circulation anomaly associated with it.When the TP1 sea temperature is forcing, the mid-high latitude of Eurasia presents a "+-+" situation from west to east at the height of 500 hPa, forming a typical pattern of two ridges and one trough; when the TI2 is forcing, it mainly causes low-and middle-level water vapor anomalies, the warm and wet air flow from the Arabian sea enters the southern part of the plateau, and the wet air flow from the northwest Pacific enters the northern part of the plateau, providing moisture conditions for snowfall.Under the configuration of this high and low layer, it is prone to snowy years.
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