降水波动是气候变化研究的主要内容之一, 同时是一个环境变化的重要指标和植被生产力预测的首选因素。本文以科尔沁地区18个气象观测站点1961-2015年逐日降水数据为基础, 根据多年平均降水量将科尔沁地区划分为4个区, 分别为Ⅰ、Ⅱ、Ⅲ和Ⅳ区, 并且综合运用小波分析方法, 分析了科尔沁地区近55年来降水变化的时空特征。研究表明, 在统计学特征上Ⅰ、Ⅱ、Ⅲ和Ⅳ区在研究期内年均降水量分别为337.4±76 mm、369.2±73.2 mm、422.6±68.8 mm和483.4±97.1 mm, 波动空间分异特征主要表现在降水量从东南（Ⅳ区）到西北（Ⅰ区）逐渐减少, 变化趋势逐渐复杂；从降水年代际变化特征来看, 降水距平值增加时Ⅰ区降水距平百分比最大, 为12.95%；降水距平值减小时Ⅰ区偏离平均值最大, 距平百分比为-19.26%。从小波分析结果来看, 降水量年际波动存在多个主周期, 其中最显著的周期为5~11年和23~32年, 且从东南到西北其周期震荡性逐渐减弱, 周期变化时间缩短。从周期性的强弱来看, 在具有共性23~32年周期内, 26~32年时间尺度模值较大, 说明该时段是降水量周期变化较明显时期；5~11年时间尺度的周期变化次之, 其他时间尺度的周期性变化较小。从空间分区的小波方差分析结果来看, Ⅰ、Ⅱ、Ⅲ区的降水主周期在10~11年之间, 而Ⅳ区为25年, 说明科尔沁地区在年降水量小于450 mm的区域降水波动特点一致, 大于此值则变化规律明显不同。从年降水量多-少的周期性变化规律可以推测, 科尔沁地区在2016-2020年期间将一直处于降水偏少期。
Annual precipitation pulse is one of the principal factors in climatic change research.It is not only an important indicator of that, but also a dominant factor for vegetation production prediction.In order to realize the recognition of the annual precipitation pulse characteristics, the research focused on the Morlet wavelet analysis method to analyze the temporal and spatial change based on eighteen meteorological station data during past decades in Kerqin sandy land region.The results showed that the annual precipitation were 337.4±76 mm, 369.2±73.2 mm, 422.6±68.8 mm and 483.4±97.1 mm in Ⅰ, Ⅱ, Ⅲ and Ⅳ sub-area during study period, respectively.The characteristics were gradually decreased from the southeast (Ⅳ sub-area) to the northwest (Ⅰ sub-area) in spatial scale and the complexity enhanced in temporal scale.On the aspects of interdecadal mean precipitation, the Ⅰ sub-area had the maximum percentage as 12.95% when the precipitation increased and the minimum percentage as -19.26% when the precipitation decreased.In addition, the Morlet wavelet analysis showed that there were double significant milt-temporal changing periods of 5~11 years and 23~32 years, and oscillation period was weak gradually in the above mentioned spatial scale and the periodic duration was gradually decreased simultaneously.However, the periodic intensity was more in 23~32 years than in 5~11 years and the most modulus value emerged in 26~32 years among 23~32 period, which indicated the precipitation periodic changed most significantly in this period.There were rest temporal scale periods too, but had less periodic change.Due to sub-area's wavelet variance results, we also indicated that Ⅰ, Ⅱ and Ⅲ sub-area had same dominant period at 10~11 year cycle and Ⅳ sub-area emerged at 25 years.So, it could be concluded that the regional precipitation fluctuation characteristics had same regime when annual precipitation is less than 450 mm and the regime was significantly different when the annual precipitation is more than 450 mm.According to the period oscillation change trait of the annual precipitation, we also predicted that the precipitation could be less than normal from 2016 to 2020 in Kerqin sandy land region.
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