科尔沁沙地乌兰敖都地区降水特点分析

Analysis on Rainfall Characteristics at Wulanaodu Region, Inner Mongolia

分析了科尔沁沙地西部乌兰敖都地区 2 1年的降水特点和降水趋势。年平均降水量为 31 1 .4mm ,降水集中在 5 - 9月份。夏季占全年降水量的 70 .1 % ,年平均降水日数约 76天。≥ 5 .0mm、≥ 1 0 .0mm的降雨日数全部集中于 3— 1 0月份。历年最长连续降水日数多发生于夏季 ,占 85 %。相对于年平均降水量 31 0mm而言 ,本地正常降水年份占 43%。异常降水年份占 5 7%。最长干旱持续期出现在冬春两季 ,约占 80 %。 2 1年平均降水量波动较大 ,并存在总体下降的趋势 ,可能与 1 999- 2 0 0 2年的年降雨量低于多年平均降雨量有关。

An analysis on rainfall characteristics during 1981-2002 at Wulanaodu Region was carried out. The mean annual rainfall was 311.4 mm,most of which falling between May to Sept. Rainfalls occurringin summer accountedfor 70.1% of the total in a year. There were 76 raining days in a year. The rainfall with the mount ≥5.0mmand ≥10.0mmconcentrated in the period from May to Oct.. Rainfalls lasting for more than one day mainly occurredin summer, accounting for 85% of the total. Compared with mean annual rainfall (310mm), years with normal annual rainfall occountedfor 43% of the total years, and ones with abnormal rainfall accounted for 57%. Drought lasted longer usually accurred in winter and spring, which accountedfor 80% of the total drought . In the period 1981-2002, the annual rainfall showed a fluctuating and decreasing trend, but the annual rainfall of 1999-2002 lower than the mean annual rainfall of 21 years.