中国84个主要城市大气热岛效应的时空变化特征及影响因子

Spatiotemporal Variations in Atmospheric Urban Heat Island Effects and Their Driving Factors in 84 Major Chinese Cities

日益加剧的城市化致使我国城市热岛效应日趋严重,进而严重影响区域环境和人类健康.目前有关我国城市热岛效应的研究多基于卫星遥感获取的辐射温度,有关大气热岛效应时空变化格局的认识相对薄弱.本文选取84个代表性城市,基于1960~2017年逐日气温观测数据,分析了我国大气城市热岛的地理分布特征及其昼夜、年内和年际变化趋势.结果表明,所有城市平均热岛强度为(0.9±1.1)℃,不同地区热岛强度差异明显,北部地区明显高于南部地区,华北地区最大,年均强度达(1.4±1.4)℃;不同时间和季节热岛强度差异大,尤其东北和西北地区,整体表现为夜晚[(1.2±1.1)℃]明显高于白天[(0.5±1.2)℃],白天夏季高于冬季,夜晚冬季高于夏季;从年际变化来看,大部分城市年平均热岛强度呈明显增加态势,平均增长速率达到0.040℃·(10 a)^(-1),但在2009年后出现明显减弱趋势;通过分析热岛强度与局地气候和不透水面的关系,结果发现大气热岛强度空间分布受气候背景和气象站点位置影响较大,而长期变化受不透水面比例影响较大.本研究将深化对我国大气热岛效应变化规律的认识,为制定缓解高温热浪的城市土地利用策略提供参考.

Accelerating urbanization seriously intensifies urban heat island effects in China,which in turn affects regional environment and human health.However,the spatiotemporal patterns of atmospheric urban heat island effects remain poorly understood in China as previous research is mostly based on satellite-sensed radiation temperatures.Using long-term daily meteorological observations from 1960 to 2017,this study explored the geographical distribution of atmospheric urban heat islands over diurnal,intra-annual,and inter-annual timescales in 84 major cities in China.The results show that on average,the intensity of the urban heat island reaches(0.9±1.1)℃,although large geographical variations were detected.The intensity was,overall,larger in northern China than in southern China;North China showed the largest annual intensity of(1.4±1.4)℃,and seasonal intensity variations were high in northeast and northwest China.Here,significantly higher intensity effects were measured at night[(1.2±1.1)℃]than during the day[(0.5±1.2)℃],and in summer than winter during the day,and in winter than summer during the night.Inter-annually,the annual mean urban heat island effect has increased by an average of 0.040℃per decade,although this trend weakens after 2009.Furthermore,we found that the spatial patterns of atmospheric heat island intensity was greatly affected by climatic background conditions and the location of meteorological stations,while the long-term trends were strongly influenced by the impervious surface area.This study improves understanding of the atmospheric urban heat island effect in China and provides important insights for formulating urban land-use strategies to alleviate high temperatures and heatwaves.