基于Landsat 8 OLI/TIRS的合肥市人为热通量遥感估算研究

Estimation of Anthropogenic Heat Flux in Hefei Using Landsat 8 OLI/TIRS Data

人为热通量是城市能量收支的重要组成部分,人为热通量的定量遥感估算和验证对城市区域气候和热岛效应的研究具有重要意义。为此,利用Landsat 8 OLI/TIRS卫星数据和ERA5再分析数据集,基于能量平衡方程法估算得到2013—2020年合肥市的人为热通量,并利用站点资料对地表特征参数和能量平衡方程各分量的估算结果进行了定量评估,在此基础上分析了合肥市人为热通量的时空分布特征。所取得的主要研究结论如下:①确立了适合城市下垫面的地表温度反演算法和下行长波辐射估算方案,地表温度和下行长波辐射均方根误差分别为2.33 K和9.26 W/m^(2)。②估算得到的净辐射通量、感热通量、潜热通量和人为热通量与站点实测数据具有良好的一致性,均方根误差分别为82.00 W/m^(2)、69.51 W/m^(2)、55.19 W/m^(2)和75.47 W/m^(2)。③人为热通量空间分布比较集中,城区人为热通量较高,工业区是城区中最大的人为热排放区域,量值远高于自然下垫面;人为热通量有明显的季节变化,夏季最高,春季次之,秋冬季最小;不同下垫面人为热通量有明显差异,城区最大,农田次之,森林和水体较小,城区在春、夏、秋、冬四季的平均值分别为:280 W/m^(2)、321 W/m^(2)、203 W/m^(2)和131 W/m^(2)。研究结果对于评估大中型城市能源排放、发展状况、布局规划以及城市区域气候的研究具有重要的科学意义和应用价值。

Anthropogenic heat flux is an important term of urban energy budget.Estimation of the anthropogenic heat flux is critical for the study of urban climate and heat island effect.Therefore,the anthropogenic heat flux of Hefei from 2013 to 2020 was estimated based on the energy balance equation method using Landsat 8 satellite data and ERA5 reanalysis data.Land surface characteristic parameters and each component of the energy balance equation was quantitatively validated against in-situ measurements,then the spatiotemporal distribution of anthropogenic heat flux was analyzed.The results showed that:①The retrieval algorithm of surface temperature and the estimation scheme of downwelling long-wave radiation suitable for urban are established.The root mean square errors of surface temperature and downwelling long-wave radiation are 2.33 K and 9.26 W/m^(2),respectively.②The estimated net radiation flux,sensible heat flux,latent heat flux and anthropogenic heat flux are in good agreement with the in-situ observations,and the root mean square errors are 82.00 W/m^(2),69.51 W/m^(2),55.19 W/m^(2)and 75.47 W/m^(2),respectively.③The spatial distribution of anthropogenic heat flux is relatively concentrated,and anthropogenic heat flux in urban areas is much higher than that over the natural underlying surface;the industrial area in the main urban area is the largest anthropogenic heat flux emission area throughout the year;the anthropogenic heat flux has distinct seasonal variation,with the largest in summer,the second in spring and the smallest in autumn and winter;there are obvious differences in anthropogenic heat flux on different surface cover types,the urban area is the largest,followed by farmland,and the forest and water body are small,the seasonal average of the urban area in spring,summer,autumn and winter are as follows:280 W/m^(2),321 W/m^(2),203 W/m^(2)and 131 W/m^(2),respectively.The research results have important scientific significance and application value for evaluating the energy emissions,development status,layout planning and urban regional climate of large and medium-sized cities.