Sensitivity Analysis of GNSS-IR based Multipath Phase for Soil Moisture over Winter Wheat crop using Navigation with Indian Constellation (NavIC)

In several studies, the sensitivity of the L-band signal has been demonstrated to be useful for estimating soil moisture. Its property to easily penetrate the atmospheric barriers and vegetation cover makes it suitable for soil moisture studies. Based on this principle, some of the studies have been carried out in field of soil moisture estimation using Global navigational satellites system (GNSS). The L5 frequency band of Navigation with Indian Constellation (NavIC) has also demonstrated its potential for soil moisture investigation. In this paper, the sensitivity of NavIC L5 frequency band for soil moisture in presence of vegetation has been investigated using GNSS-IR technique. Soil moisture sensitivity during winter wheat crop field and the impact of vegetation height on the multipath phase of the NavIC signal has been analyzed. A sensitivity analysis between in situ soil moisture and multipath phase of the NavIC L5 signal has been performed with respect to different crop heights at various crop growth stages. Good correlation between soil moisture and multipath phase has been observed for the crop height less than the three times of incident wavelength. Furthermore, the increase in crop height beyond three times the incident wavelength minimizes the sensitivity of multipath phase towards soil moisture. This is the first study in GNSS-IR domain for the investigation of multipath phase sensitivity for soil moisture at various stages of crop height.