Analysis of Urban Thermal Environment by Using Artificial Satellite

为了获取与城市热环境分析相关的地表热信息，研究了利用卫星高分辨率辐射计的数字数据估算地表温度的方法。本文的研究结果总结如下：1。利用LANDSAT-5/TM传感器的热红外波段，绘制了鹿儿岛市地表温度图。虽然得到了详细的地温图，但估算的地表温度比实测值高4-5个ºC。因此。预测值必须有所提高。在考虑大覆盖对发射率影响的地表温度估算中，利用LANDSAT-5/TM传感器可见光波段将鹿儿岛市土地覆盖状况划分为7类，完成了土地利用图。在此基础上，估算了各类别的辐射率。利用NOAA-11/AVHRR可以准确地预测地表温度。但是，由于所采用的传感器分辨率较低，难以在有限的局部区域内获得详细的温度图。如果将LANDSAT-5/TM数据与NOAA-11/AVHRR数据结合使用，可以改善其缺点。鹿儿岛市地表温度图和土地利用图的长期变化表明：(1)鹿儿岛市周围的森林被砍伐后形成了大面积的住房面积，填海后形成了城区；(2)住房和城区的地表温度逐渐升高；(3)城区内的绿化区域，即鹿儿岛大学校园抑制了地表温度的升高。这种抑制作用表明，在促进城市发展的过程中，大型绿地对于维持良好的城市热环境具有非常重要的作用。

In order to obtain thermal information on the ground surface pertinent to the analysis of the urban thermal environment, an estimation method of aground surface temperature is investigated by using digital data from the high resolution radiometer of satellite. The results obtained here are summarized as follows :1.By using a thermal infrared band of LANDSAT-5/TM sensor, a ground surface temperature map of Kagoshima city is made. Although a detailed temperature map is obtained, the estimated ground surface temperature is 4-5ﾟC higher than the measured value. Thus.the predicted value must be somewhat improved.2.In estimating the ground surface temperature taking the effect of grand cover on the emissivity into account, a land use map is accomplished in which the land covering condition in Kagoshima city is classified into seven categories using visible bands of LANDSAT-5/TM sensor. Based on its map, the emissivity of each category is estimated.3.An acccurate ground surface temperature can be predicted by employing NOAA-11/AVHRR.But, it is difficult to get a detailed temperature map within a limitted local area because of lower resolution of the employed sensor.4.Its shortcoming can be improved if LANDSAT-5/TM data are used together with NOAA-11/AVHRR data.5.A secular change in both the ground surface temperature map and the land use map in Kagoshima city indicates that (1) a large housing area is prepared by clearing a forest around Kagoshima city and a reclaimed land becomes a urban district, (2) the land surface temperatures of the housing and urban district areas become gradually higher, and (3) a green zone within the urban district, i.e.the campus of Kagoshima University inhibits an increase in the land surface temperature. This inhibition suggests that in promoting urban development, a large green zone have a very important role in maintaining a favorable urban thermal environment.