Global prediction of thermal soil regimes

A thorough understanding of thermal soil regimes is critical information for a wide variety of disciplines and engineering applications as well as for the evaluation of potential and limitations of thermal and optical sensors. In this study we have developed a procedure for the evaluation of global thermal soil regimes. First, pedotransfer functions are used to derive thermal soil properties (volumetric soil heat capacity and thermal conductivity) from readily available soil data on texture, bulk density, and organic carbon. Next, the average annual soil temperature is derived from the average annual air temperature. Then, the thermal top boundaries are derived either for well-watered sites using the daily and annual air temperature amplitudes as proxies for the daily and annual soil surface temperature amplitudes or for a wide range of environmental conditions using the model HYDRUS1D. A thorough validation of the proposed procedure is needed for the quantification of the probability with which soil thermal regimes can be predicted.