Characteristics of Extreme Drought in Central and Western Asia and Its Relationship with Tropical Sea Surface Temperature

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 Severity Index （scPDSI） and ERA5 reanalysis data.The result has shown that the drought in CWA has a noticeable seasonal 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 results 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 layers of southern CWA have reduced water vapor transport from the Indian Ocean.At the same time， the atmospheric circulation in the meddle troposphere of the Eurasian continent is characterized by EU2 type teleconnection， 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 transport was not conducive to the precipitation in CWA， which led to the rapid development of drought in CWA.

Keywords

• the belt and road
• drought
• drought index
• atmospheric circulation