Estimating Surface Soil Heat Flux in Permafrost Regions Using Remote Sensing-Based Models on the Northern Qinghai-Tibetan Plateau under Clear-Sky Conditions

The ground surface soil heat flux (G₀) quantifies the energy transfer between the atmosphere and the ground through the land surface. However; it is difficult to obtain the spatial distribution of G₀ in permafrost regions because of the limitation of in situ observation and complication of ground surface conditions. This study aims at developing an improved G₀ 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 G₀ by analyzing in situ measurement data. Based on the validation of previous models on G₀; we added the solar time angle to the G₀ parameterization scheme; which considered the phase difference problem. The maximum values of RMSE and MAE between “measured G₀” and simulated G₀ using the improved parameterization scheme and in situ data were calculated to be 6.102 W/m² and 5.382 W/m²; 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 G₀ will be less than 5%. MODIS data (surface reflectance; land surface temperature; and emissivity) were used to calculate G₀ 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. View Full-Text