By using precipitation and temperature data of 124 stations in Yunnan during 1961 -2011, drought strength in Yunnan since 1961 are analyzed based on integrated meteorological drought index and daily precipitation. Extreme droughts could be appropriately chosen with drought process intensity index - 50 in Yunnan and above -100 of regional representative stations. Four extreme drought events in Yunnan, respectively in 1962 -1963, 1968 -1969, 1978 -1979 and 2009 -2010, are chosen as extreme drought year, and analysis on which indicate that the drought from autumn 2009 to early summer 2010 is the most serious one in the historical meteorological recording, and those in 1978 - 1979, 1968 - 1969 and 1962 - 1963 follow. High frequency, long duration and consistent distribution are main characteristics of droughts in Yunnan. Droughts appear in winter, spring and early summer most but autumn droughts happen most in recent years. Due to uneven distribution of precipitation, drought strength different places in Yunnan are different, extreme droughts are less in some areas in the west and southwest for more rainfalls, extreme droughts happen mostly in most places especially in the middle and east of Yunnan. Since 1970, intension and duration of extreme drought aggravated consistently.%应用云南124个站点1961-2011年的旬、日、月降水和气温资料,采用综合气象干旱指数和逐日降水分析云南1961年以来的干旱强度.以云南的干旱过程强度指数为-50、区域代表站的干旱过程用强度指数为-100以上选取极端干旱较为合适,选取干旱强度最大1962/1963、1968/1969、1978/1979和2009/2010年为极端干旱年进行分析表明,在4次极端干旱过程中,强度最强的是2009/2010年出现的秋冬春初夏连旱,是有气象记录以来最强的,其造成的危害及经济损失也最大,其次是1978/1979年、1968/1969年和1962/1963年出现的冬春初夏连旱.云南干旱灾害出现频繁、持续时间长,其分布具有一致性的特点,干旱出现的时段大致在冬、春及初夏季,而近年来秋季干旱呈频发之势.由于云南降水分布极不均,造成各地干旱强度指数存在差异.除滇西、滇西南局部边沿地区降水偏多,出现极端干旱相对较少外,云南大部,特别是云南中部及东部地区最容易发生极端干旱.从1970年代以来,云南出现严重干旱的强度及持续时间呈加重趋势.
展开▼
