全球城市热辐射方向性制图揭示了城市气候遥感的潜在偏差  

Global mapping of urban thermal anisotropy reveals substantial potential biases for remotely sensed urban climates

作　　者：杜惠琳 占文凤 刘紫涵 E.Scott Krayenhoff TC Chakraborty 赵磊 姜璐 董攀 李龙 黄帆 王莎莎 徐于月 Huilin Du;Wenfeng Zhan;Zihan Liu;E.Scott Krayenhoff;TC Chakraborty;Lei Zhao;Lu Jiang;Pan Dong;Long Li;Fan Huang;Shasha Wang;Yuyue Xu(Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology,International Institute for Earth System Science,Nanjing University,Nanjing 210023,China;Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application,Nanjing 210023,China;School of Environmental Sciences,University of Guelph,Guelph N1G 2W1,Canada;Atmospheric Sciences and Global Change Division,Pacific Northwest National Laboratory,Richland 99352,USA;Department of Civil and Environmental Engineering,University of Illinois at Urbana-Champaign,Urbana 61820,USA;School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China)

机构地区：[1]Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology,International Institute for Earth System Science,Nanjing University,Nanjing 210023,China [2]Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application,Nanjing 210023,China [3]School of Environmental Sciences,University of Guelph,Guelph N1G 2W1,Canada [4]Atmospheric Sciences and Global Change Division,Pacific Northwest National Laboratory,Richland 99352,USA [5]Department of Civil and Environmental Engineering,University of Illinois at Urbana-Champaign,Urbana 61820,USA [6]School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China

出　　处：《Science Bulletin》2023年第16期1809-1818,M0004,共11页科学通报（英文版）

基　　金：the National Natural Science Foundation of China(42171306,42001270,and 42201337)for providing support for this current study;the support from the National Youth Talent Support Program of China;supported by Coastal Observations,Mechanisms,and Predictions Across Systems and Scales-Great Lakes Modeling(COMPASS-GLM),a multi-institutional project supported by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Research as part of the Earth and Environmental Systems Modeling program。

摘　　要：城市热辐射方向性限制了遥感地表温度反演精度,阻碍了对全球城市气候(如城市地表能量通量估算和城市热环境评估)的准确理解.然而,全球不同气候背景城市热辐射方向性时空特征及其造成的城市地表能量通量和热岛强度遥感估算偏差仍不清楚,在全球尺度是否存在与城市热辐射方向性密切相关且易获取的地表和气候参量尚不明晰.本研究结合多角度卫星观测地表温度和遥感云平台,分析了全球5500多个城市的热辐射方向性特征,量化了其造成的全球城市地表能量通量和热岛强度遥感估算偏差,厘清了全球尺度城市热辐射方向性与关键地表和气候参量的关系.研究发现全球城市平均热辐射方向性强度在夏季白天下午高达5.4 K.在极端情况下,当地表温度观测天顶角位于±60°时,热辐射方向性使得全球城市地表显热通量和热岛强度分别低估45.4%和43.0%.研究进一步发现全球城市热辐射方向性与地表不透水面百分比和空气温度具有良好的统计关系,这为卫星遥感城市地表温度角度纠正提供了新思路.Urban thermal anisotropy(UTA)drastically impacts satellite-derived urban surface temperatures and fluxes,and consequently makes it difficult to gain a more comprehensive understanding of global urban climates.However,UTA patterns and associated biases in observed urban climate variables have not been investigated across an adequate number of global cities with diverse contexts;nor is it known whether there are globally measurable factors that are closely related to the UTA intensity(UTAI,quantified as the maximum difference between the nadir and off-nadir urban thermal radiation).Here we investigate the UTAI over more than 5500 cities worldwide using multi-angle land surface temperature(LST)observations from 2003 to 2021 provided by Moderate Resolution Imaging Spectroradiometer(MODIS).The results show that the global mean UTAI can reach 5.1,2.7,2.4,and 1.7 K during summer daytime,winter daytime,summer nighttime,and winter nighttime,respectively.Using nadir LST observations as a reference,our analysis reveals that UTA can lead to an underestimation of satellite-based urban surface sensible heat fluxes(H)by 45.4%and surface urban heat island intensity(Is)by 43.0%when using LST observations obtained from sensor viewing zenith angles(VZAs)of±60°.Practitioners can limit the biases of H and Iswithin±10%by using LSTs from sensor VZAs within±30°.We also find that UTAI is closely related to urban impervious surface percentage and surface air temperature across global cities.These findings have implications for angular normalization of satellite-retrieved instantaneous LST observations across cities worldwide.

关 键 词：热岛强度 城市气候 地表能量通量 地表温度 显热通量 卫星观测 空气温度 卫星遥感 

分 类 号：TU119.4[建筑科学—建筑理论] P407[天文地球—大气科学及气象学]