Abstract: S drought index was established and analyzed by using MannKendall drift test method and Morlet small wave transformation, based on monthly precipitation and nonprecipitation day′s number from 7 meteorological stations in warm season (April to October) from 1961 to 2009 in Altay, Xinjiang. The results showed that S drought index accorded with drought condition in Altay. There were 3 extreme drought years and 1 extreme wetness year in last 49 years, there were extreme drought years except for 2 east stations. There were 1 extreme wetness year in Burgin and 2 extreme wetness years in Jimunai, and not in other stations. There were 2 extreme drought years in spring and 1 extreme drought year in autumn, but no extreme wetness years. There were 2 extreme drought years and 3 extreme wetness years in summer. Wetness dominated in warm season during 1980s and 1990s, and drought usually in other time; drought dominated in spring during 1960s and wetness usually in other time. Decadal change in summer was similar to warm season, wetness dominated during 1960s and 1980s, and drought usually in other time. Small wave analysis results indicated that S drought index changed as decadal and annual cycle.

Key words: font-size: 10.5pt, mso-bidi-font-family: 宋体, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA" lang="EN-US">Altay in Xinjiang, Warm season, S drought index, Climate change