The Effect of Row Structure on Soil Moisture Retrieval Accuracy

Zheng Xingming ^1,2 , Zhao Kai ^1,2,*,Li Yangyang ¹, Ren Jianhua ¹ , Ding Yanling ¹. Soil & Tillage Research/143 (2014) 137–144.

Abstract:Row structure causes the anisotropy of microwave brightness temperature (TB) radiated from soil surface, and it also can affect soil moisture retrieval accuracy from passive microwave data when its influence is ignored in the inversion model. To study the effect of typical row structure in northeast China (65cm row spacing and 15cm row height) on soil moisture retrieval accuracy and evaluate whether there is a need to introduce this effect into soil moisture inversion model, two ground-based experiments were carried out during June 2011 and October 2011. Based on brightness temperature observed from C-band radiometer during the experiment, field soil and vegetation parameters, row structure rough surface assumption (Qp model and discrete model), including the effect of row structure, and flat rough surface assumption (Qp model), ignoring the effect of row structure, are used to model soil surface microwave brightness temperature. Then, soil moisture can be retrieved respectively by minimizing the difference of the measured and modeled brightness temperature. The results show that soil moisture retrieval accuracy based on the row structure rough surface assumption is approximately 0.02cm3/cm3 better than the flat rough surface assumption for vegetated soil, as well as 0.015cm3/cm3 better for bare and wet soil. This result indicates that the effect of row structure in northeast China cannot be ignored for accurately retrieving soil moisture of farmland surface when C-band is used

Keywards:microwave, row structure, soil moisture, farmland