南京地区地表热通量的遥感反演分析

Analysis and Inversion on Surface Heat Flux with Remote Sensing in Nanjing Area

利用南京地区2013年8月11日、2013年10月14日、2014年1月2日和2014年5月26日的4景Landsat 8 OLI/TIRS1B遥感影像,结合地面气象观测资料,借助SEBAL模型反演了南京地区地表热通量,并利用地表温度实测数据进行验证,且与他人研究结果进行了比较。结果表明,(1)南京净辐射通量与土壤热通量表现为春季最大,夏季次之,冬季最小;感热通量呈暖季(春、夏)大于冷季(秋、冬)的特征;秋季潜热通量最大,冬季最低,夏春季居中。(2)南京净辐射通量值为长江最高,均值达614.8 W·m^(-2);湖泊与林地次高,均值大于500 W·m^(-2);旧城、草地、农田较高,均值在480~500 W·m^(-2)之间;裸地与新城最低,均低于460 W·m^(-2)。土壤热通量值为旧城、裸地、新城最高,均值在75~85 W·m^(-2)之间;湖泊、农田、草地次之,均值在65~75 W·m^(-2)之间;长江与林地最低,均值低于60 W·m^(-2)。感热通量值为城区最高,均值均高于200 W·m^(-2);林地、裸地、农田、草地次之,均值在100~200 W·m^(-2)之间;水体区域最低,均低于60 W·m^(-2)。潜热通量值为水体区域最高,均值高于400 W·m^(-2);林地、草地、农田、裸地次高,均值在220~320 W·m^(-2)之间;城区潜热通量最低,均低于200 W·m^(-2)。(3)土壤热通量占净辐射的比值除冬季均低于0.1外,其余季节均在0.05~0.25之间;新老城区的感热通量占净辐射比值在四季典型日均高于0.4,除春季的裸地和冬季外,其余土地利用类型均低于0.3,水体区域均低于0.15。潜热通量占净辐射比值为水体区域在四季均高于0.7,新老城区均低于0.5,除春夏季裸地和冬季的林地外,其余土地利用类型均高于0.5。不同土地利用类型的波文比呈现"新城>旧城>裸地>林地>农田>草地>湖泊>长江"的空间分布和"春季>冬季>夏季>秋季"的时间分布。新城区的波文比在四季典型日均为最高,且均值大于1,而水体的均为最低,均值小于0.2。

Based on four Landsat8 OLI/TIRS 1B remote sensing images on 11th August and 14th October in 2013, 2nd January and 26th May in 2014 in Nanjing, combined with the meteorological data measured by the ground meteorological station, this study retrieved the temporal and spatial distribution of surface heat flux in Nanjing area by SEBAL model, As the surface temperature was validated with the measured data and the reliability was validated by comparing with others results. The results showed that: (1) net radiation flux and soil heat flux on the maximum value were in spring, lower value were in summer and the minimum value were in winter. Sensible heat flux in the warm season (spring and summer) was higher than the cold season (winter and autumn). Latent heat flux on the maximum value was in summer, the minimum value was in winter and lower value was in spring and autumn in Nanjing area. (2) The maximum net radiation flux located in Yangtze River, which average and value was 614.8 W·m-2. The higher value were in lake and woodland, which average value was higher than 500 W·m-2. The higher value were in old city, farmland and grassland, which average value were during 480 to 500 W·m-2. The minimum value were in bare land and metro area, which average value were lower than 460 W·m-2. The maximum soil heat flux located in old city, bare land and metro area, which average value were durin 75 to 85 W·m-2. The higher value were in lake, farmland and grassland, which average value were during 65 to 75 W·m-2. The minimum value were in Yangtze River and woodland. which average value were lower than 60 W·m-2. The maximum sensible heat flux located in old city and metro area, which average value was higher than 200 W·m-2. The higher value were in woodland, bare land, farmland and grassland, which average value were during 100 to 200 W·m-2. The minimum value was in water, which average value was lower than 60 W·m-2. The maximum latent heat flux located in water, which average value was higher than 400 W·m-2; The second value were in woodland, grassland, farmland and bare land, which average value were during 220 to 320 W·m-2. The minimum value were in old city and metro area, which average value was lower than 200 W·m-2. (3) Soil heat flux accounted for the net radiation flux was less than 0.1 in winter, other seasons were during 0.05 to 0.25. Sensible heat flux accounted for the net radiation flux in typical day of the four seasons were more than 0.4, other land use types were less than 0.3 except bare land in spring and winter. And Water less than 0.15. Old city and metro area were lower than 0.5. Other land use types were higher than 0.5 except bare land in spring and summer and woodland in winter. The Spatial distribution of Bowen ratio in different land use types in Nanjing area were “metro area > old city > bare land > woodland > farmland > grassland >lake > Yangtze River” and the time distribution were “spring > winter > summer > autumn”. The maximum Bowen ratio was in metro area in typical day of the four seasons, which average value was higher than 1. The maximum value was in body, which average value was lower than 0.2.