Abstract:

Based on the daily observed meteorological data from 585 meteorological stations in mainland China from 1961 to 2020, this study analyzed the spatiotemporal distribution and variability characteristics of the temperature on the twenty−four solar term scale. The interdecadal differences in temperature within solar terms were also clarified, as well as the changes in the onset and duration of climatological seasons under the background of climate change. The results showed that the highest temperature occurred during the Lesser Heat and Greater Heat solar terms in mainland China from 1961 to 2020, which was 24.1℃ and 24.4℃, respectively. A noticeable coolness appears in the North China Plain during the White Dew and Autumnal Equinox solar terms, marking the onset of the climatological autumn. The Lesser Cold and Great Cold solar terms showed the lowest average temperature with the mean value of −2.8℃ and −2.5℃, respectively. The average temperature of the whole country showed a significant change characteristic of stronger in north than south of China, with drastic changes in spring and autumn during the transition of solar terms. The Pure Brightness−Grain Rain and Awakening of Insects−Spring Equinox solar terms exhibited the highest temperature increases (3.6℃and 3.4℃, respectively), while the Beginning of Winter−Lesser Snow solar term showed the largest temperature decrease (−3.9℃). The temperature changes during spring and autumn solar terms were significantly more pronounced in Northeast and North China compared to other regions. Under the background of climate change, the isotherms of the threshold temperatures (0℃, 10℃and 22℃) have shifted northward, while the duration of climatological summer becoming longer and winter shorter. These changes were more pronounced in northern regions compared to southern regions. Compared to the period from 1961−1990 (period I), the average temperature increase during winter and spring solar terms in 1991−2020 (period II )(0.6−1.9℃) was greater than that in summer and autumn solar terms (0.5−0.9℃), and the Rain Water solar term showed the largest increase. The changes in the duration of climatological seasons were most significant in Northeast, North and Northwest China, where summer duration increased by 6.7−8.6 days, and winter duration decreased by 7.1−9.3 days. The findings provide scientific evidence for optimizing regional agricultural climate resource allocation and formulating differentiated agricultural adaptation strategies to enhance climate resilience under the changing climate. 

Key words: Twenty?four solar terms, Mean temperature, Spatiotemporal distribution, Climate change