近54 a三江平原地区初霜冻指标特征研究

利用1961—2014年国家基本(准)站初霜冻日资料,对三江平原地区初霜冻日进行从长时间序列趋势线性变化、多重周期性变化以及长时间序列突变性3个方面的特征研究。表明:(1)三江平原地区的初霜冻日均值沿东南方向逐渐递增,全区域初霜冻日均值纵跨尺度约为5 d。三江平原各地区的综合初霜冻日时间总体上开始延后,这可能与全球整体变暖的温室效应有相关性。(2)54 a中三江平原地区初霜冻日变化倾向率空间分布展现出"两峰值中心,两谷值中心"的变化特征。两峰值中心是指以佳木斯、双鸭山地区为高增量中心,呈现初霜冻日变化倾向率幅度由此向外逐步递减的趋势。两谷值中心则是指以富锦、宝清地区初霜冻日变化倾向率由此向外递减的低值中心。峰值中心较谷值中心的倾向率幅值相差约1.5 d/(10 a)。综合小波分析法与HHT-EEMD法中对三江平原地区近54 a初霜冻日均值变化周期分析结果表明三江平原主要存在两个尺度周期:2~5 a的年际周期、28 a左右的年代际周期。(3)初霜冻日均值突变指数的交叉点出现在1969年,通过α=0.05显著性水平检验,此突变点时间可作为将来进行气候背景场的研究点。

Study on the characteristics of early frost in Sanjiang plain area in recent 54 years

By using the first frost date data of national basic (quasi) station during 1961 to 2014, the characteristics of first frost date in Sanjiang plain from three aspects:long time series trend linear change, multiple periodic change and long time sequence were analyzed. The results show that:(1)The initial frost days in Sanjiang plain area are gradually increasing along the southeast direction, and the average vertical span of the whole region is about five days. The overall early frost date of the various regions of Sanjiang plain is delayed, which may be related to the global warming. (2)The spatial distribution of the diurnal variation tendency of the first frost in the Sanjiang plain in 54 years shows the characteristics of "two peak centers and two valleys centers". The two peak centers refer to Jiamusi and Shuangyashan areas as the high incremental centers, which presents the trend of the beginning of the first frost on the gradual decline in the rate of outward trend. The two valleys centers refer to the low-value centers in which the diurnal variation tendency of the first frost in Fujin and Baoqing areas is decreasing outward. The amplitude of the center of the peak is about 1. 5 d/(10 a). The analysis on the variation cycle of daily average early frost days in nearly 54 years in Sanjiang plain areas by integrated wavelet analysis method and HHT-EEMD method show that the Sanjiang plain had two main scale period:the interannual cycle of 2-5 a and the decadal cycle of about 28 a. (3)The crossing point of mean mutation index of the first frost day appeared in 1969, which is tested by 95% significance level and can be used as the research point of the climatic background field in future.