Modeling geothermal regime in the Qinghai-Tibet Plateau: an examination of the upper-boundary condition
- PDF / 434,226 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 55 Downloads / 149 Views
ORIGINAL PAPER
Modeling geothermal regime in the Qinghai-Tibet Plateau: an examination of the upper-boundary condition Yinghong Qin & Ting Bao
Received: 10 March 2012 / Accepted: 17 February 2013 # Saudi Society for Geosciences 2013
Abstract This study describes to which degree the numerical prediction of ground temperatures in the Qinghai-Tibet Plateau is influenced by the upperboundary 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 upperboundary models. Keywords Temperature-controlled upper boundary . Heatflux upper boundary . Zero-curtain zone . Global warming . Initial ground temperature
Y. Qin (*) College of Civil Engineering and Architecture, Guangxi University, 100 East University Road, Nanning, Guangxi 530004, China e-mail: [email protected] T. Bao Faculty of Engineering, China University of Geosciences, Wuhan, China 430074
Introduction Numerical models are popular for predicting the groundtemperature distribution in the Qinghai-Tibet Plateau because field observations for these temperatures are expensive, time consuming, and only can predict temperature in specific, instrumented locations (Lai et al. 2006; Qin and Li 2011; Zhang et al. 2005). These models must utilize a proper upper boundary since heat flux to the ground comes mainly through surface mechanisms. Currently, these models use either a temperature-controlled upper boundary (TCUB) or a heat-flux upper boundary (HFUB). It is needed to differentiate whether the use of different upper boundaries causes significantly different predicted ground-temperature profiles in the plateau. A TCUB is simple but cannot be used to directly estimate the influences of site-specific weather conditions, e.g., air temperature, wind speed, etc., on the ground temperature (Lai et al. 2006; Qin and Tang 2011). In comparison, a HFUB is relatively complicate, but its formulation must assess the impact of local weather conditions on the ground-surface heat flux. However, it remains unknown whether the ground-temperature profiles predicted by a TCUB agree with those by a HFUB and whether these predicted results deviate from the field observations. This paper describes the impacts of the upper-boundary adoptions on the predicted ground-temperature profile in the Qinghai-Tibet Plateau. It focuses on the deviation between the prediction
Data Loading...
