丽水市四季起始日期的气候演变特征

The Variation Characteristics of Seasons Start Dates in Lishui

根据丽水市国家气象观测站1953—2010年逐日气温资料,运用趋势分析、Morlet小波变化和Mann-Kendall检验对四季起始日期的气候变化特征、趋势演变规律和突变转折情况进行了研究。结果表明:四季起始日期,春季约在3月中旬,夏季在5月底,秋季在9月下旬,冬季在11月下旬,且春、秋季的长度较短,只有2个月左右,夏、冬季的长度较长,长达4个月。Morlet小波分析四季起始日期的周期变化特征,主要体现在年代际时间尺度上,且各周期强度有所差异,预测春、夏季起始日将按照提前趋势发展,秋、冬季起始日继续延后状态。MannKendall检验得出,春、夏两季起始日期在21世纪初发生由推后转向提前的突变,而秋、冬两季起始日突变点都体现在20世纪60年代。

Based on the daily temperature data supplied by Lishui National Meteorological Observatory from 1953 to 2010, the trend analysis, Morlet wavelet transform and Mann-Kendall test were used to analyze the climate variation, time-frequency characteristics and abrupt change of seasons start dates. The results showed as follows. Spring started at mid-March, summer started at the end of May, autumn at late September and winter at late November. The length of spring and autumn were shorter, only two months, the length of summer and winter were longer, about four months. There were different periodic oscillations mainly on decadal scales and cycles varied in intensity. The trends of seasons start dates presented that springs and summers started earlier, and autumns and winters started later. The result of Mann-Kendall test showed that spring and summer start dates became earlier because of the abrupt change in the early 21th century, while autumn and winter start dates had the mutation in the 1960s.