气候变化领域集成服务门户

The ground surface soil heat flux (G(0)) quantifies the energy transfer between the atmosphere and the ground through the land surface. However; it is difficult to obtain the spatial distribution of G(0) in permafrost regions because of the limitation of in situ observation and complication of ground surface conditions. This study aims at developing an improved G(0) parameterization scheme applicable to permafrost regions of the Qinghai-Tibet Plateau under clear-sky conditions. We validated several existing remote sensing-based models to estimate G(0) by analyzing in situ measurement data. Based on the validation of previous models on G(0); we added the solar time angle to the G(0) parameterization scheme; which considered the phase difference problem. The maximum values of RMSE and MAE between measured G(0) and simulated G(0) using the improved parameterization scheme and in situ data were calculated to be 6.102 W/m(2) and 5.382 W/m(2); respectively. When the error of the remotely sensed land surface temperature is less than 1 K and the surface albedo measured is less than 0.02; the accuracy of estimates based on remote sensing data for G(0) will be less than 5%. MODIS data (surface reflectance; land surface temperature; and emissivity) were used to calculate G(0) in a 10 x 10 km region around Tanggula site; which is located in the continuous permafrost region with long-term records of meteorological and permafrost parameters. The results obtained by the improved scheme and MODIS data were consistent with the observation. This study enhances our understanding of the impacts of climate change on the ground thermal regime of permafrost and the land surface processes between atmosphere and ground surface in cold regions.