时间升尺度方法对城市地表热岛强度计算的影响研究

Impacts of Temporal Upscaling Methods on Calculation of Surface Urban Heat Island Intensity

时间升尺度方法多用于减轻或消除卫星观测数据的缺失对城市热环境遥感研究的不利影响,然而不同时间升尺度方法对城市地表热岛强度计算是否存在差异,且该差异在多时间尺度上如何变化尚不明确。针对上述问题,该文对SMW平均法、ATCS和ATCE模型法3种时间升尺度方法进行了系统比较,总结了3种方法对城市地表热岛强度计算的影响及规律。结果发现:模型法(ATCS和ATCE)与SMW平均法的时间合成数据存在较大差异;晴空像元比例对基于3种方法生成的热岛强度影响显著,但随比例增加,热岛强度值愈加接近;多时间合成尺度下,SMW平均法和模型法计算的年内热岛强度最大值出现在不同的季节;随时间合成尺度的增大,SMW平均法的热岛强度变化较大,而模型法的热岛强度变化较稳定。总体表明:当卫星观测数据较多时,SMW平均法能够有效监测城市热环境;若卫星观测数据较少,应优先选择ATCE模型法。

Temporal upscaling methods are frequently used to eliminate the adverse effects of satellite observation gaps in the study of surface urban thermal environment.However,the impacts of different temporal upscaling methods on the calculations of surface urban heat island intensity （SUHII） remain unclear.In view of this,this paper systematically compared the simple moving window （SMW） average method with ATCS- and ATCE-based methods,and summarized the impacts of these three methods on the SUHII calculations.It is found that the model based methods （ATCS and ATCE） and the SMW average method produced very different results.The SUHII is significantly affected by the proportion of clear-sky pixels.The intensities calculated by the three methods reach the similar level as the proportions increase.At multiple time scales,the highest SUHII values calculated by SMW average and ATC-based （ATCS- and ATCE-based） methods appear in different seasons.In addition,the SUHII calculated by the SMW average method shows larger variation with increase of the time scales compared with the ATC-based ones.Through quantitative analysis of the effect from temporal upscaling strategies on the SUHII calculations,we can conclude that,when the satellite observation dataset is large,the SMW average method is the most effective,while a small dataset is available,the ATCE model method is preferred.We believe our study can potentially provide assistance to a more accurate assessment of the urban thermal environment.