Evaluating three measurement methods of soil ground heat flux based on actively heated distributed temperature sensing technology: Fid-Bau Portal

Evaluating three measurement methods of soil ground heat flux based on actively heated distributed temperature sensing technology

Sun, Meng-Ya / Shi, Bin / Cui, Yu-Jun / Tang, Chao-Sheng / Zheng, Xing / Zhong, Peng / Wang, Yun-Qiang / Tong, Yong-Ping

Abstract

Abstract Soil ground heat flux (G 0) is a key parameter in analyzing soil-atmosphere interaction. It is not only an indispensable component in the surface energy balance, but also an essential boundary condition in the coupled hydro-thermal-mechanical (HTM) numerical analysis of soil-atmosphere interaction. In this study, three G 0 measurement methods (gradient method, calorimetric method and combination method) are evaluated based on the measurements (temperature, volumetric water content and thermal conductivity) using the actively heated distributed temperature sensing (AH-DTS) technology. In addition, through a series of in-situ tests, the feasibility of these methods is verified, and their applicability and application potential are compared and analyzed. The results indicate that the G 0 values measured by the three AH-DTS technology-based methods are in the same order of magnitude, indicating that the three methods are feasible. Among them, the G 0 measured by the gradient method is an instantaneous value which is closely related to the soil surface water content, while the G 0 measured by the calorimetric method and combination method is an average values over a period of time. The gradient method is applicable for all types of soil, including the frozen soils. The calorimetric method and the combination method are suitable for soils of which water content can be measured by the AH-DTS sensor. It is recommended that an appropriate G 0 measurement method based on the AH-DTS technology be selected according to the site situations.

Highlights • The three AH-DTS-based methods for soil ground heat flux measurement are proposed. • The feasibility of the three methods is verified through a series of in-situ tests. • The characteristics and applicability of three methods are compared and analyzed. • The AH-DTS technology provides a new means for determining soil ground heat flux.