北京1951—2008年升温趋势和季节变化

采用均一化订正的北京南郊地面日平均气温资料,分析了北京地区1951—2008年气温变化趋势。结果表明,年平均最高和最低气温的升高呈明显的不对称性,其中年平均最低气温升高较为明显,升温趋势为0.46℃/10a。根据1951—2008年日平均气温计算北京春、夏、秋、冬四季的季节长度和起始日期,发现北京地区冬季最长,秋季最短;夏季在逐渐延长,冬季在逐渐缩短,夏、冬两季长度变化的线性速率分别为4.4d/10a和-4.7d/10a。春、夏两季逐渐提前,趋势分别为3.0d/10a和2.5d/10a;而秋、冬两季在逐渐推迟,趋势分别为2.0d/10a和1.7d/10a。将季节起始日期与年平均气温进行相关性分析发现,春、夏两季的起始时间与年平均气温存在显著负相关,而秋、冬两季起始时间与年平均气温存在显著正相关。

Warming Trend and Seasonal Variation in Beijing During 1951-2008

The warming trend in Beijing was analyzed based on the homogenized land surface air temperature data at Nanjiao weather observatory during 1951-2008. The analysis shows that the mean maximum and minimum temperatures increased asymmetrically at a rate of 0.26℃/10a and 0.46℃/10a, respectively. It is found that among four seasons winter is the longest season and autumn is the shortest season; summer is getting longer at a rate of 4.4 d/10a, and winter is becoming shorter at a rate of 4.7 d/10a; since 1951 the starting dates of spring and summer have become earlier at a linear rate of 3.0 d/10a and 2.5 d/10a, and on the contrary, the starting dates of autumn and winter have gradually become later at a rate of 2.0 d/10a and 1.7 d/10a respectively. The correlation analysis suggests that the starting dates of spring and summer are significantly negatively correlated with the annual mean temperature; while those of autumn and winter are remarkably positively correlated with the annual mean temperature.