TWO METHODS FOR REMOTE ESTIMATION OF COMPLETE URBAN SURFACE
TEMPERATURE
Complete urban surface temperature (<i>T</i><sub>C</sub>) is a key parameter for evaluating the energy exchange between the urban surface and atmosphere. At the present stage, the estimation of <i>T</i><sub>C</sub> still needs detailed 3D structure information of the urban surface, however, it is often difficult to obtain the geometric structure and composition of the corresponding temperature of urban surface, so that there is still lack of concise and efficient method for estimating the <i>T</i><sub>C</sub> by remote sensing. Based on the four typical urban surface scale models, combined with the Envi-met model, thermal radiant directionality forward modeling and kernel model, we analyzed a complete day and night cycle hourly component temperature and radiation temperature in each direction of two seasons of summer and winter, and calculated hemispherical integral temperature and <i>T</i><sub>C</sub>. The conclusion is obtained by examining the relationship of directional radiation temperature, hemispherical integral temperature and <i>T</i><sub>C</sub>: (1) There is an optimal angle of radiation temperature approaching the <i>T</i><sub>C</sub> in a single observation direction when viewing zenith angle is 45&ndash;60°, the viewing azimuth near the vertical surface of the sun main plane, the average absolute difference is about 1.1&thinsp;K in the daytime. (2) There are several (3&ndash;5 times) directional temperatures of different view angle, under the situation of using the thermal radiation directionality kernel model can more accurately calculate the hemispherical integral temperature close to <i>T</i><sub>C</sub>, the mean absolute error is about 1.0&thinsp;K in the daytime. This study proposed simple and effective strategies for estimating <i>T</i><sub>C</sub> by remote sensing, which are expected to improve the quantitative level of remote sensing of urban thermal environment.
