不同时间尺度下中国舒适度时空分布变化及成因研究OA

Based on the daily mean temperature,wind speed,and relative humidity data from 585 national meteorological stations across China for 1961-2020,using the Body Comfort Meteorological Index(BCMI)and GIS-based spatial interpolation,the spatiotemporal variations of human climatic comfort across China were systematically analyzed at annual,seasonal,monthly,and solar-term scales.Sensitivity analysis and contribution-rate methods were used to identify the drivers of changes in human comfort and to quantitatively compare the relative roles of temperature,wind speed,and humidity across regions and seasons.The main findings are as follows.From 1961 to 2020,China experienced an annual average of 180 comfortable days,with lower values in the northwest and higher values in the southeast.This pattern broadly reflected the combined effects of latitude,elevation,and monsoon circulation,with arid and high-altitude inland areas having fewer comfortable days and humid monsoon regions having more.Over the past 60 years,the national annual average number of comfortable days increased at a rate of 2.8 days per decade,indicating an overall improvement in climatic comfort.The increases were more pronounced in Southwest and North China,whereas decreases in comfortable days were concentrated in the south-central part of South China,reflecting marked regional heterogeneity in the long-term evolution of comfort.In spring and autumn,14.9％and 6.6％of the national meteorological stations shifted from cold discomfort to comfort,indicating a widespread reduction in cold-related discomfort during the transition seasons.In summer,parts of Central China,North China,South China,among other regions,shifted from comfort to heat discomfort,suggesting an intensified warm-season thermal burden in densely populated areas.Rising temperature was the dominant factor driving changes in BCMI values,followed by decreasing wind speed,and their combined effects explained most of the observed station-level transitions.In addition,some stations in Hubei,Hunan,Sichuan,and Chongqing experienced increased wind speed and a slight decline in summer temperature,leading to a shift from heat discomfort to comfort and further demonstrating the spatial non-uniformity of climatic forcing mechanisms.The Grain Buds solar term had the largest comfortable area nationwide,with comfortable stations accounting for 93.2％of all national stations,indicating that late spring to early summer is generally the most favorable period for human climatic comfort in China.By contrast,the periods from Minor Heat to Major Heat and from Minor Cold to Major Cold showed the greatest nationwide extent of heat discomfort and cold discomfort,accounting for 28.1％and 92.3％of total national stations,respectively.This result reveals a clear intra-annual contrast,with heat stress concentrated in midsummer and cold stress dominating in midwinter at the national scale.Compared with period I(1961-1990),period Ⅱ(1991-2020)showed an extended comfortable period:the onset of the spring comfortable period advanced from the Beginning of Summer to Grain Rain,while the end of the autumn comfortable period was delayed from Autumn Equinox to Cold Dew.Moreover,summer heat discomfort increased,whereas winter cold discomfort weakened notably.Overall,although the annual comfort window has expanded,intensified summer heat discomfort indicates growing climate-health risks in warm seasons,highlighting the need for region-specific adaptation strategies and season-targeted risk management.