Modeling geothermal regime in the Qinghai-Tibet Plateau: an examination of the upper-boundary condition

This study describes to which degree the numerical prediction of ground temperatures in the Qinghai-Tibet Plateau is influenced by the upper-boundary adoptions. A temperature-controlled upper boundary and a heat-flux upper boundary (HFUB) are, respectively, applied to model the ground temperatures at a typical section on the plateau. Predicted temperatures are compared to the field-observed temperature profile at this test section, in order to distinguish the predicted deviations. Comparison of these deviations confirms that a HFUB model promises better prediction accuracy, especially in the modeling ground-temperature zero-curtain effect. Adoption of a HFUB, however, requires examining whether the specified initial ground temperature is in its thermal equilibrium state. Special emphasis is paid on how to use a HFUB to simulate the temperature under a pavement in the plateau and on the pro and con regarding the uses of different upper-boundary models.