城市地表热通量遥感反演及与下垫面关系分析

选择日本埼玉县熊谷市为研究区,应用ASTER热红外遥感图像,采用PCACA模型以及理论定位算法,对城市地表热通量的相关参数进行反演,进而分析城市下垫面不同土地覆盖类型对地表热通量以及能量平衡的影响.结果表明,PCACA模型应用于城市区域地表通量估算是可行的.这种算法可以大大减少在下垫面结构复杂的城市区域进行地表热通量估算时所需的参数,并有效降低研究结果的不确定性.研究发现,城乡不同下垫面地表覆盖类型对地表热通量的影响差异显著.不同地表下垫面类型的波文比由大到小顺序依次为:工业用地＞住宅用地＞交通用地＞公共设施用地＞旱田＞公共绿地＞水域.在相同的外部气象条件下,与城市周边的植被覆盖区相比,城市人工建筑用地具有较高的显热通量,较低的潜热通量,以及较高的波文比.由于城市地表显热通量和波文比明显高于周边植被覆盖地表,导致城市地表向低层大气供热的增加,这是城市热岛效应形成的重要机制之一.

Urban Surface Heat Flux Inversion Based on Infrared Remote Sensing and the Relationship with Land Cover

This study extracted urban surface heat flux parameters based on PCACA model using ASTER infrared remote sensing image, and then analyzed the impacts on urban surface heat flux and energy balance from different land cover types in the experimental area of Kumagaya City, Saitama Prefecture of Japan. The results indicate that this method on application PCACA model to estimate surface flux in urban areas is feasible. This algorithm can greatly reduce the complexity of the underlying surface structure of the urban areas of surface heat flux estimates, and decrease the uncertainty of the results. The study found that urban and rural areas of different land cover types on the surface heat flux were significantly different. According to urban land use and cover types, Bowen ratio is industrial, residential, traffic, establishment, dry field, public green and water body in a descending order. In the same weather conditions, surrounding vegetation and urban areas compared to urban land has a high sensible heat flux, the lower the latent heat flux, and the higher Bowen ratio. The urban surface sensible heat flux and Bowen ratio was significantly higher than that of the surrounding vegetation surface, leading to urban surface heating of the lower atmosphere. This is an important mechanism for the formation of urban heat island effect.