Abstract:

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.

Key words: Surface-air temperature difference, Spatiotemporal distribution, Climate change, China