Drought variations in the eastern part of northwest China over the past two centuries: evidence from tree rings

Drought reconstruction from 1794 to 2003 in the eastern part of NW China was developed by calibrating tree rings of Picea wilsonii on Xinglong Mountain with the Palmer drought severity index (PDSI).The reconstruction explains 40% of the actual PDSI variance during the period from 1951 to 2003.The most significant drought period over the reconstructed time span occurred during the 1920s to 1930s.The drought reconstructions show a climate transition in 1921 on a decadal scale and significant cyclic patterns that were identified in intervals of 10.5, 7.9-8.3,~3.5, 3.0-3.2,2.7-2.8 and ~2 yr.This reconstruction is representative of regional drought patterns in eastern NW China and demonstrates that they are different from patterns in western NW China.