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利用1981-2013年西藏山南地区月降水、连续无雨日数等资料,分析山南地区不同季节干旱等级、年季变化及发生频率。结果表明,近30 a山南地区最长无雨日数春季和初夏沿江一线和西部呈增多趋势,而盛夏沿江一线和西部减少,南部增多;春季、初夏干旱20世纪80年代为高发期,21世纪春旱和初夏干旱明显减少,盛夏干旱在20世纪80-90年代中期及2005年后呈高发期;春季干旱一般集中出现在西部和沿江中段一带,初夏干旱出现在隆子、沿江一线南部和西部一带,盛夏干旱主要出现在沿江中西段、西部和南部措美一带,而山南地区南部错那等边缘地区基本没有出现干旱。
Based on the data of monthly precipitation and continuous non-rainy days in Shannan Prefecture in Tibet during 1981-2013, the variation of drought level, annual variation and frequency in different seasons of Shannan were analyzed. The results showed that the maximum rainy days in Shannan in the recent 30 years showed an increasing trend in the first and the western part of the Yangtze River in spring and early summer, while the decrease in the first and the western part of the Yangtze River in summer and the increase in the south during spring and early summer. In the early 1980s, Drought and drought in early summer decreased significantly. Drought in midsummer was high in the mid-1980s to the mid-1990s and later in 2005. Spring drought generally occurred in the middle part of the west and along the Yangtze River. Early summer drought appeared in the southern and western parts of the Yangtze River, Drought in midsummer mainly occurred in the central-western part of the Yangtze River, in the western part and in the southern part of the Cuomei area, while no drought occurred in the marginal areas such as the southern part of the Shannan area.