A data-driven method to remove temperature effects in TDR-measured soil water content at a Mongolian site

Abstract

As a convenient, easy-to-use tool, time-domain reflectometry (TDR) is becoming extensively used to measure soil water content. Used not only in hydrological applications, the measurements are also used as ground truth for satellite remote sensing of soil moisture. However, TDR measurements usually include diurnal fluctuation caused by diurnal change of temperature. Though this is an old problem, there is not a general solution. The purpose of this study is to develop an algorithm to remove temperature effects of TDR measurements by analyzing its relationship with meteorological variables. From data observed at a Mongolian site, it is found that impact of soil temperature on soil water content is nearly proportional to soil temperature itself and soil water content. An algorithm is developed and applied to the Mongolian data set. The temperature effects can be effectively removed under dry and wet conditions.