甘肃张掖市冬季气温变化的时空特征

依据张掖市近50年来的冬季气温观测资料,运用Mann-Kendall法、小波分析、空间插值等方法,对张掖市冬季气温的时空分布规律和变化周期进行分析。结果表明:冬季气温总体上呈现增暖的趋势(β值为0.08),线性增长率为0.56℃/10a,相当于近50年冬季气温升高了2.8℃,冬季增温对全年升温的贡献率高达89%。1985年冬季气温发生突变,之后进入偏暖期,1987年后增温趋势更加显著。冬季气温存在10年左右和22年左右的振荡周期,其中22年左右的振荡周期较强。冬季气温空间分布不均,呈现出由东南向西北逐渐增温的趋势。冬季气温从20世纪70年代起就开始增温,东部增温速度明显高于西部,冬季气温增暖主要发生在最近的20余年内。

Spatiotemporal variation characteristics of winter temperature in Zhangye City

The meteorological data of 6 national stations covering the 49-year period from 1956 to 2004 were analyzed to understand the spatial-temporal characteristic about temperature variation in winter over Zhangye city,by employing the approach of linear trend analysis as well as Mann-Kendall rank analysis,wavelet analysis and spatial interpolation.It was observed that there was an obvious ascending tendency of winter air temperature from 1956 to 2004 at the α=0.1 significant level(β=0.08)in this region,or a warming rate of 0.56℃/10a in winter.The result indicated that the winter temperature of this region increased by 2.8℃ in the last five decades.Besides,it was also found that the winter warming contributed 89%to that of the whole year.Compared with Northwest China and the whole country,the warming rate was similar to the former but higher than the latter.During the study period,there was a lowest average winter temperature point in 1967 and a highest one in 1987 with an abrupt change point in 1985.prior to the point was a cool stage and after it a warm stage emerged especially after 1987,which was similar to the winter temperature variation of Hexi Corridor.In the last half century,there was typical oscillation such as 6a and 22a in winter temperature variation,particularly,the 22a oscillation dominated.Spatial variation of winter temperature indicated that there was an obvious ascending tendency from southeast to northwest in the study area.By Mann-Kendall analysis it was found that six subregions showed a similar warming trend at the α=0.1 significance level,compared with the other five.Shandan station experienced the highest warming trend with β=0.21 and a warming rate 0.94℃/10a.Generally speaking,winter temperature warming mainly appeared in the last 20 years and the warming rate of the eastern part was higher than that of the western.Additionally,some problems to be solved in future were briefly analyzed.