Exploration of empirical relationship between surface soil temperature and surface soil moisture over two catchments of contrasting climates and land covers

摘要

Soil moisture plays a very important role in hydrological processes. It has been found in many studies that the surface soil moisture (SSM) is highly related to the diurnal change of the surface soil temperature(triangle SST) at the same soil depth. However, some studies contradict this common belief with findings of a much stronger correlation between the SSM and the SST. In order to investigate this further, we have carried out for the first time a comparative assessment of the insitu measured SST and triangle SST for SSM estimations, over two catchments with contrasting climate types and land uses (i.e. one in the UK and the other in Australia). In both catchments, the time point for the highest relationship between the SST and the SSM is explored. As a result, it is found the SST is more suitable to monitor the variability of the SSM than the triangle SST in both catchments. Moreover the proposed seasonalbased classification method further improves the SSM simulation results in both catchments, with a superior performance observed in the UK catchment (NSE = 0.900 and RMSE = 0.030). In the Australian catchment, a relatively weaker correlation is observed and some potential reasons are explained. The potential applications of the findings for remote sensing soil moisture retrievals are also discussed.