科尔沁沙地奈曼旗1970—2010年降水的多时间尺度分析

利用回归分析、小波分析和Mann-Kendall （M-K）突变分析研究了1970—2010年奈曼旗的降水变化特征。结果表明：（1） 不同雨量级中，0~5 mm降水事件最多，占全年降水事件的70%以上，其降水量也最多，占全年降水量的18%；降水间隔期以0~5 d为主，占全年无降水期的73%。（2） 1970—2010年奈曼旗年降水及季降水波动较大，基本呈相对少雨期和相对多雨期相间分布的特征；年降水及春、夏、秋和冬季降水的倾向率分别为-12.4、0.8、-3.2、-1.3 mm/10a和-0.3 mm/10a； 年降水及春、夏和秋季降水在1990年左右以正距平为主，而在1985年之前和1995年以后以负距平为主；冬季降水基本随年份增加呈减少的趋势。（3） 1月降水量最少，7月最多。7月降水量约占年降水量的30%以上，且与其他各月相比均有显著差异。（4） 通过小波分析发现，奈曼旗年降水存在6~8年的较短周期和17年左右的较长周期变化；年降水和夏、秋及冬季降水在进入21世纪后都有减少趋势。（5） M-K突变分析表明，奈曼旗年降水减少及春季降水增加的突变点分别为 2004年和2006年。

Multiple-time-scale Analysis on Precipitation in Naiman Bannerof Horqin Sandy Land in 1970-2010

The change trends of Naiman's precipitation patterns during 1970-2010 were analyzed by using linear regression, wavelet analysis and Mann-Kendall (M-K) mutation analysis. The results showed that, (1) Precipitation in the research area was dominated by small precipitation events with 0-5 mm, accounted for 70% of the total events, and up to 18% of the total precipitation amount. The precipitation interval was dominated by 0-5 days, accounted for 73% of the total days without precipitation. (2) In 1970-2010, the annual precipitation and seasonal precipitation changed complex, shown a dry wet dry process; The tendency rate of annual precipitation and spring, summer, autumn and winter precipitation was 12.4, 0.8, 3.2, 1.3 and 0.3 mm/10a, respectively; Annual precipitation and spring, summer and autumn precipitation have been positive anomaly about 1990, and negative anomaly before 1985 and after 1995. Winter precipitation showed a decreasing trend generally. (3) The precipitation was least in January, while a greatest in July and the July's precipitation accounted for more than 30% of the total precipitation amounts. And there was a significant difference in precipitation amount between the July and the other month. (4) Morlet wavelet analysis found that annual precipitation had a shorter cyclical fluctuation of 6-8 years and a longer cyclical fluctuation of 17 years in this region. Annual precipitation and summer, autumn and winter precipitation decreased in the beginning of the 21^st century; (5) M-K mutation analysis showed that a reduce trend for annual precipitation and an increase trend for spring precipitation, and the start of abrupt time was 2004 and 2006, respectively.