Spatiotemporal drought variability for central and eastern Asia over the past seven centuries derived from tree-ring based reconstructions

摘要

The availability of the first tree-ring based drought reconstructions for the entire central and eastern Asia (CEA) allowed comprehensive investigation of its spatiotemporal hydroclimate features for the past seven centuries. Drought variability of ten factors in the context of Asian monsoon and westerlies was analyzed. The Angkor drought (the 1350-60s and the 1420s-30s) and the Ming Dynasty drought (1630s -40s) occupied much area of the CEA, which may be related to the decay of both the westerlies and Asian summer monsoon. The drought during the late 15th century are mainly found over the eastern part of the CEA, possibly due to the weakening of the western North Pacific summer monsoon (WNPSM) and the East Asia summer monsoon (EASM). The dry epoch during the 1720s-30s is widespread over the high Asia and northeastern Asia, possibly due to the weakening of the westerlies and the EASM. The 1950s wetting trend may be related to the warming-induced strengthening of Asian monsoon, while drying tendency since the 1980s may be associated with the strengthened Hadley cell and intensified human activities. Teleconnections between droughts in northeastern Asia and regions of Afghanistan, Pakistan and Tajikistan may be explained by the positive associations of the Indian summer monsoon (ISM) and EASM with the strength of the anticyclone in northeastern Asia.