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

Lu Zhuo,Dawei Han,Qiang Dai

doi:10.1007/s12517-017-3183-x

Abstract

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 (∆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 in-situ measured SST and ΔSST 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 ΔSST in both catchments. Moreover the proposed seasonal-based 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.

Highlights

Soil moisture plays a very important role in hydrological processes (Kerr et al 2001; Zhuo et al 2015); in particular, the surface soil moisture (SSM) has been widely recognised as a vital element in a number of environmental studies
The first two thirds of the data are selected for calibration, and the remaining data are used for validation purpose
The accuracy is measured by Nash-Sutcliffe efficiency (NSE) and root mean square error (RMSE)

Summary

Introduction

Soil moisture plays a very important role in hydrological processes (Kerr et al 2001; Zhuo et al 2015); in particular, the surface soil moisture (SSM) has been widely recognised as a vital element in a number of environmental studies. Wanders et al (2014) found that calibrating large-scale hydrological models with satellite-retrieved surface soil moisture resulted in Ban accurate identification of parameters related to landsurface processes^ (Wanders et al 2014: pp 6874). Yoon and Leung (2015) showed that Bantecedent soil moisture information was as important as concurrent ENSO condition in controlling rainfall anomalies over the United States" (Yoon and Leung 2015: pp 5005). In hydrology, the presence of sufficient moisture in the upper-most few centimetres of soil plays an important role in controlling and distributing water input from rainfall and irrigation into runoff, interflow and groundwater (Idso et al 1975). Accurate soil moisture information is essential in real-time flood forecasting, as well as decision making in water resource management (Brocca et al 2010; de Michele and Salvadori 2002; Komma et al 2008; Zhuo and Han 2016; Zhuo et al 2016; Srivastava et al 2013b; Srivastava et al 2016)

Methods

Results

Conclusion