中国夏季干湿型热浪天气时空分布及环境舒适度评价

Spatial-temporal variation of summertime dry/wet heat wave events and evaluation of environmental comfort level in China

基于中国气象局对热浪天气的定义并参考地理分区和热浪日湿度分级标准,定义连续3 d以上地面最高气温≥35℃的天气过程为热浪,选取1960-2018年476个地面气象站观测数据研究中国夏季干热型和湿热型热浪日数的时空分布特征及其变化趋势。结果表明,中国夏季热浪日数除新疆外呈现东南高、西北低的空间分布格局,江南地区夏季热浪发生日数最多(年均15 d)。温湿指数和人体舒适度指数评价结果表明江淮地区热浪天气期间环境舒适度最差,热浪天气对人体的不利影响更显著。相对于内陆地区,沿海地区因海风影响午后气温显著降低,有利于缓解热浪天气的影响,因而沿海站点夏季热浪日数比邻近的内陆站点偏少。除黄淮地区外中国大多数站点热浪日数均呈现增加趋势,江苏、浙江沿海、广东、重庆、海南、新疆及广西东部热浪日数增加趋势显著(1~5 d·(10 a)^(-1),α=0.05);中国东部和东南沿海湿热型热浪增加趋势显著,增幅达1~5 d·(10 a)^(-1);浙江、江西北部、甘肃、新疆等地区干热型热浪日数显著增加(α=0.01)。1990年以来全国夏季热浪天气发生更为频繁;其中2000-2009年间干热型热浪日数偏多,而2010年之后强湿热型热浪日所占比例增加。

According to the definition of heat wave by China Meteorological Administration,geographical zones,and grading standard of humidity in heat wave days,a heat wave event is defined to be a process when the surface maximum air temperature equal to or higher than 35℃in three consecutive days in the study.The spatial-temporal distribution and variation trend of the number of the summertime dry/wet heat wave(HW)days from 1960 to 2018 are investigated using the data from 476 meteorological stations in China.It is found that the number of the summertime HW days decreases from Southeast China to Northwest China(except for Xinjiang)and the Jiangnan region experiences the most frequent HW events(about 15 d per year).The evaluation results of temperature-humidity index(THI)and the comfort index of human body(ICHB)identifies the worst environmental comfort level during HW over the Jianghuai region,where the adverse effects of HW on human body are more significant.The sea breeze can significantly reduce the afternoon air temperature and alleviate the impact of the summertime HW in the coastal areas,and the number of HW days in the coastal stations is less than that in the adjacent inland stations.Except for the Huanghuai region,the number of HW days increases at most stations in China and the increasing trend is significant(1-5 d·(10 a)^(-1),α=0.05)in Jiangsu,the coastal areas of Zhejiang,Guangdong,Chongqing,Hainan,Xinjiang,and the east of Guangxi;the number of wet HW days increases significantly by 1-5 d·(10 a)^(-1) over the east and southeast coast of China;the number of dry HW days also increases significantly(α=0.01)in Zhejiang,the north part of Jiangxi,Gansu,and Xinjiang.The summertime HW events have been more frequent in China since 1990;the number of dry HW days is more from 2000 to 2009,while the proportion of strong wet HW days have increased since 2010.