Utilizing Tree Ring Chronologies to Reconstruct 300-Year Drought Days in Eastern Tianshan Mountains

The major local tree ring chronology (1665~1989) in the Eastern Tianshan Mts was obtained by averaging 6 tree ring chronologies. The response surfaces of tree ring to climate indicate that growth of spruce in the Eastern Tianshang Mts is nonlinear correlated with precipitation and temperature. This interaction makes it unreasonable to reconstruct either precipitation or temperature, separately, using regression methods. Drought days during tree growth season were estimated from regression model including both temperature and precipitation which would influence tree-ring growth. The relationship between tree ring and drought days is significant. As a result, the local past drought days back to 1665 A. D. at Miquan and Fukang, Eastern Tianshan, were reconstructed based on spruce tree-ring chronologies. The results are coincided with the actual situation.