基于Hurst指数的黑龙江省作物生长季降水趋势研究

A study on rainfall trend during the crop growing season in Heilongjiang province based on Hurst exponent method

基于黑龙江省78个气象站1971—2016年逐日降水资料,综合采用墨西哥帽小波分析、Hurst指数分析等方法,对黑龙江省作物生长季(5—9月)降水量变化和未来趋势进行分析及预测。结果表明:1971—2016年,黑龙江省生长季、5月、6月降水量存在7 a、14 a、7 a左右的主周期,7月、8月、9月降水量存在2 a、3 a、7 a左右的第1主周期及6 a、11 a、21 a左右的第2主周期,各月均存在最近几年降水偏多的趋势;作物生长季降水量年际间为波动式振荡变化,7月、8月振荡幅度相对较大。年代际变化总体存在增加—减少—增加趋势,20世纪80年代、90年代降水量普遍偏多,2010年以来出现急转升高变化;单站各月Hurst指数均在0.5以上,降水存在比较明显的赫斯特现象;降水主要出现在夏季且以7月最为集中,最近几年降水偏多、7月异常降水集中以及主要流域未来7月降水的持续增加趋势在农业防灾减灾上值得关注。

Based on daily precipitation data from the 78 meteorological stations in Heilongjiang province from 1971 to 2016,this paper analyzed the historical and future trends of precipitation change during the crop growing season(from May to September)in Heilongjiang province by using the methods of Mexican-hat wavelet transform and Hurst exponent.The results show that there are the major quasi-periods of 7 years,14 years and 7 years in the growing season,May and June,respectively,and the first quasi-periods of 2 years,3 years and 7 years as well as the second quasi-periods of 6 years,11 years and 21 years in July,August and September,respectively,for precipitation in Heilongjiang province during 1971-2016.Meanwhile,the precipitation in each month shows an increasing trend in recent years.The precipitation in growing season shows a fluctuant interannual variation and the change amplitudes are relatively large in July and August.In addition,the precipitation experiences an interdecadal change of increase-decrease-increase pattern.Specifically,the precipitation is above the normal level in the 1980s and 1990s and sharply increases since 2010.The Hurst exponent of each month is above 0.5 at each station,which means that there is an obvious Hurst Phenomenon for precipitation.Precipitation mainly occurs in summer,especially in July.The facts that the precipitation increases and concentrates abnormally in July in recent several years as well as persistently increases in main river basins in July in the future are worthy of attention in agricultural disaster prevention and mitigation.