中文摘要：

城市是陆地生态系统中极为重要的地表覆盖类型，把握其热辐射特征对于研究城市地表能量平衡和城市热岛具有积极的意义。相对于自然地表，城市区域表现出更为显著的热辐射方向特征，但这方面的研究直到近年来才开始发展起来。对城市区域的航空遥感和地表观测试验均揭示，城市区域热辐射方向性与太阳一地面目标一传感器几何关系、城市形态与结构、地面目标物理性质等密切相关。同时，为描述城市区域热辐射方向性，辐射温度三维格局模型、几何模型以及辐射传输模型都相继建立起来。从热辐射方向性的试验观测、模型建立及其与城市热岛关系等角度入手，系统回顾了城市区域热辐射方向性的研究进展，并对已经取得的研究成果进行了总结。最后，指出了尚待解决的问题及今后应着重研究的方向。

英文摘要：

Urban surface is one of the most important land cover types in the land surface ecosystem. Investigations on thermal radiation features of urban surfaces are helpful for researches about energy balance in urban environments and urban heat islands （UHIs）. Thermal anisotropy in urban areas is more significant than that of natural surfaces. However, related researches have been slowed down. In recent years, observations onboard air-crafts and ground platforms have revealed that thermal anisotropy in urban area is related to the geometric conditions of sunground targets-sensor, the configurations and physical features of urban areas. In addition, models for describing the radiative temperature patterns, geometric relationships and radiative transfer schemes in urban areas have been proposed by literatures. In this study, the progresses of researches about thermal anisotropy in urban areas have been reviewed from several aspects, including experiments, modeling and the relationships between thermal anisotropy and surface UHI. It is also pointed out that the issues remain further investigation.