Research on the spatial and temporal evolution characteristics of perpetual spring climate in China based on quantitative evaluation indicators

Based on daily observation data by 1815 national meteorological stations in China from 1961 to 2024, focused on the core elements of perpetual spring climate - temperature and climate comfort, 15 meteorological evaluation indicators were selected and perpetual spring climate evaluation index system was developed. The normalization and weight coefficient methods were used to construct t perpetual spring climate index, and this index was used to quantitatively evaluate the temporal and spatial evolution characteristics of perpetual spring climate in China. The results show that perpetual spring climate is mainly distributed in most of Yunnan, southern Sichuan, and southwestern Guizhou. The resource advantages of perpetual spring climate in most of Yunnan and southern Sichuan were obvious. From 1961 to 2024, perpetual spring climate index showed a significant increasing trend, and the interannual variation of perpetual spring climate index became more stable after 1985. Within the evaluation index system, trends in winter indicators, as well as in annual comfortable days and annual temperature range, are favorable for perpetual spring climate resources, whereas trends in summer indicators and spring and autumn comfort days exert adverse effects. The formation of perpetual spring climate in China is influenced by the combined effects of low latitude and high altitude, with stations typically located at elevations between 600 and 2,200 meters, and the change trend of perpetual spring climate index is significantly correlated with the altitude. Based on perpetual spring climate evaluation index system and perpetual spring climate index, this provides a quantitative and precise assessment of perpetual spring climate resources. The findings can offer scientific support for the development and utilization of climate resources, thereby better serving tourism, wellness, and other related industries.