浙江丽水市降水特征多时间尺度周期变化规律的探究

Multi-time-scale Characteristic of Precipitation Cycle Evolution in the Past 58 Years in Lishui of Zhejiang Province

根据丽水市1953～2010年逐月降水量资料,在利用趋势分析方法对年际、年代际、季度、月份降水变化趋势进行分析的基础上,运用多窗口谱分析方法对降水的周期特征进行研究,并将显著周期信号进行MTM重建,寻找不同时间尺度上的显著周期随时间的振荡演变规律。结果表明:近58 a来,丽水降水量呈下降趋势,约每10 a降水减少10.19 mm,其中春季5月和秋季9月降水量减少最为显著,夏季8月增多最明显。降水周期特征的多窗口谱分析表明,降水在年代际尺度上的12 a周期最显著,且周期振幅随时间变化分布均匀,同时在年际尺度上2～4 a的周期也较明显,且振幅具有缓变包络的特征。

Based on the monthly precipitation data from 1953 to 2010 in Lishui of Zhejiang Province,the change tendency method was used to analyze monthly,seasonal,annual and decadal variation characteristics of precipitation in Lishui,then the precipitation cycle characteristic was analyzed by multi-taper method in order to investigate the cycle evolution of precipitation.The results showed that the precipitation in Lishui presented a decreasing trend with the rate of 10.19 mm/10 a in the past 58 years,in May and September precipitation reduced obviously,but increased in August.It was found that the precipitation was characterized by obvious cycle change with 12 years on decadal scale,and 2-4 years cycle was also obvious with slowly varying envelope characteristics.