台山单站降水的多尺度振荡特征

应用功率谱、Morlet小波变换和Butterworth带通滤波处理等方法,对1954—2018年台山站的年降水序列和逐日降水序列数据进行多尺度振荡特征分析。研究表明:台山站年降水量存在11~13、准4、准25年的周期振荡,前汛期降水量存在准13、2~5年的周期振荡,后汛期降水量存在7~8、准20、3~4、准11年的周期振荡。台山站逐日降水振荡基本表现为天气尺度振荡、准单周振荡、准双周振荡、季节内振荡和季节变化振荡等5种尺度,季节内及以下尺度振荡强度相当,季节变化振荡强度较弱。5种时间尺度的标准差,天气尺度最大,季节变化尺度最小,除季节变化振荡外均呈现出周期性循环特征。在汛期雨量偏少年,逐日降水较易呈现出准单周振荡和天气尺度振荡,而汛期雨量偏多年较易呈现出准双周振荡。

Characteristics of Multiple Scale Oscillations of Site Precipitation in Taishan

Using the methods of power spectrum,Morlet wavelet transform and Butterworth band-pass filtering,this paper analyzes the 1954—2018 multiple scale oscillation characteristics of annual and daily series of precipitation at an observation station in Taishan.The result is shown as follows.For the annual precipitation amount,there are periodic oscillations at 11~13,quasi-4 and quasi-25 years.For the precipitation amount in raining seasons,periodic oscillations are at quasi-13 and 2~5 years April through June and at 7~8,quasi-20,3~4 and quasi-11 years July through September.For the daily precipitation amount,the oscillations are generally on the synoptic,quasi-single-weekly,quasi-biweekly,intraseasonal,and seasonal scales.The oscillations at the intraseasonal scale and below are comparable in intensity but those at the seasonal scale is quite weak.The standard deviation of the five temporal scales is the largest for the synoptic scale but the smallest for the seasonal scale,all showing periodic cycling except for the seasonal oscillation.In the years with relatively small raining-season precipitation amount,it is more likely for the daily precipitation to oscillate at the quasi-single-weekly and synoptic scales,and in the years with relatively large raining-season precipitation amount,it is more likely for it to oscillate at the quasi-biweekly scale.