Interannual Variability in August Drought in Northern China and the Corresponding Climate Shift

Abstract

AbstractThis study examines August droughts in northern China (north of 35°N) at interannual and interdecadal timescales. During the period from 1968 to 1992, the precipitation in the western and eastern regions of northern China showed an out‐of‐phase pattern. During the period from 1994 to 2018, the climate in the Tarim Basin became wetter, but there was no significant connection with drought in North China. Further studies demonstrated that the Atlantic sea surface temperature (SST) and regional soil moisture anomalies were related to drought changes in northern China. Before the early 1990s, the east‐west standardized precipitation index dipole mode in northern China was physically linked with the wet soil in central Asia in the preceding June; moreover, the wet land surface could persist until August and cause anticyclonic and cyclonic systems over Mongolia and the subtropical northwestern Pacific, thus contributing to precipitation surplus in northwest China and a deficit in North China. After the early 1990s, however, wet conditions over the Tarim Basin were related to wet soil in the East European Plain in the preceding July: the wet soil could persist into August and generate anomalous circulation over the Tarim Basin, leading to abnormal humidity. Additionally, the SST conditions in the North (South) Atlantic are key sources of climate predictability for northern China drought at the interseasonal scale after (before) the early 1990s.