中国西北近46a夏季气温的时空变化特征分析

为了整体分析中国西北干旱半干旱区夏季(6~8月)气温的时空变化特征,利用该区137个测站1961-2006年历年夏季平均地面气温资料,采用线性趋势分析、多项式拟合、EOF、REOF、Mann-Kendall、滑动t-检验、子波分析和功率谱分析等方法,分析该区夏季气温异常的空间分布、时间演变特征及对气候变暖的响应。结果表明:1)中国西北干旱半干旱区夏季近46a平均气温19.5℃,且年际变化较小。2)在20世纪70年代中期发生由降温到升温的转变,1994年以后变暖趋势更加明显,并在1996发生了增温的突变。全区温度变化存在7a和4a左右的周期,目前,气温仍处于偏高周期。3)根据EOF分析,夏季气温异常可分为全区一致型、准东西向差异型、准南北差异型。经REOF分析,进一步突出局地特征细分为6个区:高原区、蒙陕甘宁区、北疆区、南疆区、蒙新甘区、东部区。4)全区夏季46a增温率为0.24℃/10a,近10a变暖趋势更加明显,其中高原区、蒙陕甘宁区、蒙新甘区对全区夏季增温贡献最大。南、北疆区和东部区增温较小,局地有下降趋势,表明大部分区域增温显著,同步响应全球变暖。

Analysis of temporal and spatial variation characteristics of summer surface air temperature in northwest China over the recent 46 years

To analyse the temporal and spatial change features of the summer air temperature in arid and semi-arid area of northwest china as a whole,Using the summer mean surface air temperature data over the years of 1961-2006 of 137 stations and the methods of linear regression analysis、multinomial fitting、EOF、REOF、Mann-Kendall、Glide T-examination、Wavelet analysis and power spectrum analysis etc,we analyzed the characteristics of spatial distribution and temporal evolvement for temperature abnormality and the response of the averaged air temperature of summer to climate warming.The result shows that: 1)The mean air temperature of summer was 19.5℃ and the annual variation was small.2)The summer temperature changed from reducing to increasing in mid-1970s,the ascending tendency was more evident from 1994 and the abrupt change occurred in 1996.There were about 7or 4 years periodic change for the summer temperature and the current cycle was still higher.3)According to the EOF analyses,the summer temperature anomaly distribution was divided into three main modes: with the same temperature variation in all areas,with the different ones in the east and west or in the south and north.According to the REOF analyses,divided the area into six subregions further.4)The rates of change of summer mean temperature reached 0.24℃/10a for the pass 46 years and warming trend more evident in the past 10 years.The temperature changing trend was increasing obviously in most of the area with the exception of parts area of Xinjiang,and synchronized response to global warming.