亮温与地表温度表征的城市热岛尺度效应对比研究

利用ASTER数据反演亮温和地表温度,并对二者差异进行对比;利用地统计学界定采样的最大尺度范围,并分别将亮温和地表温度影像以原分辨率为基础进行尺度下推分析,在多尺度分割基础上,构建热岛面积百分比、热岛强度两个指标,用于表征城市热岛尺度效应的差异性。结果表明:亮温和地表温度在数量结构、表征地物温度变异程度上存在很大差异;随着像元尺度增加,用亮温和地表温度表征的城市热岛面积百分比存在明显的尺度效应,且前者明显强于后者,但二者表征的城市热岛强度的尺度效应不明显,且后者稍强于前者;二者表征的城市热岛面积百分比和热岛强度均存在明显差异,表明亮温表征城市热岛的欠合理性。鉴于以上不同,在相关研究中应谨慎选取研究尺度和温度类型。

Comparison on Scale Effect of Urban Heat Island Defined by Brightness Temperature and Land Surface Temperature

Brightness temperature and land surface temperature are extracted from ASTER data set,and their difference is analyzed.The maximum pixel scale is circumscribed using geostatistics technology,and the downscaling methods are applied to both brightness temperature and land surface temperature(LST) starting with resolution of 90m.Based on this,two indexes,namely area percent of urban heat island(UHI) and intensity of UHI,are selected to investigate the difference on scale effect of UHI defined by the two types of temperature.The result shows that in terms of quantity structure and validity on indicating temperature variance of objects,LST is better than brightness temperature.In addition,with the pixel scale increasing the scale effect of area percent of UHI define by two temperatures is obvious,furthermore,the brightness temperature is more undulate than LST,reversely the scale effect of intensity of UHI is inconspicuous,but the LST is correspondingly more undulate than brightness temperature.Simultaneously,large differences of specific values are yielded in terms of both area percent and intensity of UHI,indicating the inconformity of the brightness temperature for UHI study.In addition,it is noted that it is important to choose appropriate resolution and the temperature types for the UHI studies.