Long-term change in relative humidity across China from 1961-2018

Abstract

Using observational data of daily relative humidity obtained from 2479 meteorological stations from 1961-2018 and the homogenized monthly data set of national ground meteorological stations, this paper analyzes the climate change characteristics of average relative humidity across China as well as in 9 individual regions. From 1961-2018, the climate change trend in annual average relative humidity across China was negligible, but there were large differences among different regions. Overall, annual relative humidity in the Qinghai-Tibet Plateau and Xinjiang area showed a significant increase, while Northwest China, Northeast China and northern North China showed a significant decrease. Seasonally, average relative humidity in China chiefly decreased in spring, and there was no discernable trend in other seasons. The Qinghai-Tibet Plateau showed a significantly increasing trend in winter, spring and summer, especially in spring; Xinjiang exhibited a significant increasing trend in winter, summer and autumn; Northeast China presented a significantly decreasing trend in winter; Northwest China, North China, Central China and East China witnessed a significantly decreasing trend in spring; and South China and Southwest China showed a slightly decreasing trend across all 4 seasons. Large urban agglomerations exert an influence on relative humidity to some degree, with urban areas experiencing lower relative humidity than rural areas.