中国地气温差时空分布及变化趋势

利用中国825个气象站点1961—2016年的逐日地表温度和气温观测资料,系统分析了中国地区地气温差（地表温度减气温）的时空分布以及变化趋势。结果表明,中国多年平均的年地气温差西部大部地区及华南部分地区在2.5℃以上,而中东部大部地区在2.5℃以下。其中春、夏季全国各地地气温差均为正值,且总体呈经向型分布,西高东低;秋、冬季中国各地地气温差总体呈纬向型分布,南高北低,尤其是冬季北方部分地区为负值。年内,中国区域平均各月地气温差均为正值,其中1月份和12月份相对较小,6—8月份（夏季）相对较大。不同地区地气温差的年内分布特征有所不同,西藏地区地气温差年平均值为全国最大,最大值出现在雨季来临前的5月份;东北、华北、黄淮、西北及内蒙古地区最大值均出现在雨季来临前的6月份;江淮、江汉、江南、华南地区地气温差最大值均出现在雨季过后的7月份或8月份;西南地区年内各月地气温差变化相对较小,在雨季之前的5月和雨季之后的8月出现2次峰值,呈双峰型分布。1961—2016年,中国区域平均地气温差4月和4—10月上升趋势较明显,而7月和10月变化趋势不明显或略有上升趋势。空间分布上,东北、西北及内蒙古、西藏西部等地平均地气温差有增加趋势,而中东部地区有减小趋势。

The spatiotemporal characteristics and long-term trends of surface-air temperatures difference in China

In this study, we analyzed the temporal and spatial distributions and long-term linear trend of surface-air temperatures difference (ΔT) in China. The values of ΔT were calculated based on the daily surface and air temperature measured at 825 weather stations from 1961 to 2016. The results showed that the annual ΔT was above 2.5℃ in most of western China and parts of South China, while below 2.5℃ in most of central and eastern China. In spring and summer, the ΔT was positive and generally distributed meridionally, high in western China and low in eastern China. In autumn and winter, the ΔT was generally distributed zonally, high in southern China and low in northern China. Especially in some areas of northern China, ΔT was negative in winter. The average monthly ΔT in China was positive, but it was relatively low in winter (January and December) and high in summer. The intra-annual distribution characteristics of ΔT varied across regions. The annual ΔT in Tibet was the highest in China with the maximum in May prior the rainy season. The regional average ΔT in the Northeast China, North China, Huanghuai region, Northwest China and Inner Mongolia reached the peak in June before the arrival of the rainy season. The maximum ΔT appeared in July or August after the rainy season in Yangtze-Huaihe region, Jianghan, south of the Yangtze River and South China. The monthly ΔT in Southwest China had smaller change and had two peaks respectively in May before the rainy season and August after the rainy season. From 1961 to 2016, the countrywide mean ΔT displayed an upward linear trend in April and from April to October, while there was no significant linear trend in July and October. The ΔT had an increasing trend in Northeast China, Northwest China, Inner Mongolia, and western Tibet, while a decreasing trend was identified in central and eastern China.