Page 59 - 《高原气象》2022年第5期

高 原 气 象 41 卷
1152

Characteristics of Extreme Drought in Central and Western Asia and

Its Relationship with Tropical Sea Surface Temperature

1
1
WU Zhiwen ，QIN Zhengkun ，LIN Zhaohui 2
（1. Data Assimilation Research and Application Joint Center of Nanjing University of Information Science
and Technology，Nanjing 210044，Jiangsu，China；
2. International Center for Climate and Environment Sciences，Institute of Atmospheric Physics，
Chinese Academy of Sciences，Beijing 100029，China）

Abstract：As a hub of the“Belt and Road”（B&R），Central and West Asia（CWA）was significantly threatened
by droughts. The study of drought that occurs in CWA is of great value to the successful implementation of B&R.
This work analyzed the main characteristics of drought in CWA using the self-calibrating Palmer Drought Severi‐
ty Index（scPDSI）and ERA5 reanalysis data. The result has shown that the drought in CWA has a noticeable sea‐
sonal difference. The drought almost started from the boreal winter，rapidly intensified in spring，and reached
the peak at the end of spring，then relieved slowly in summer. By using the composite analyses method，this
work examined the differences in climate systems between extreme droughts and humid events in CWA. The re‐
sults show that the tropical Pacific Sea surface temperatures anomaly（SSTA）exhibited a La Niña pattern in the
early stage of extreme drought events，which results in the continued northwards winds anomaly in the lower lay‐
ers of southern CWA have reduced water vapor transport from the Indian Ocean. At the same time，the atmo‐
spheric circulation in the meddle troposphere of the Eurasian continent is characterized by EU2 type teleconnec‐
tion，resulting in positive height field anomaly in the region and continuous enhancement. The air movement
driven by the positive height field anomaly was mainly subsidence. Besides，the reduction of water vapor trans‐
port was not conducive to the precipitation in CWA，which led to the rapid development of drought in CWA.
Key words：The Belt and Road；drought；drought index；atmospheric circulation