Bare Soil Freeze/Thaw Process Detection Using GNSS-R/IR Techniques: A Case Study in Alaska, USA

GNSS-IR is a new emerging remote sensing technique, and it utilizes the interference signal of direct and reflected signals for geophysical parameters retrieval. Nowadays, its application include soil moisture, snow depth, vegetation water content and sea level detection. This paper has extended its application to monitor soil freeze/thaw process. Mixed material dielectric constant model is employed to get the dielectric constant change as soil freeze/thaw process occurs. Forward GPS multipath model is used to establish the quantitative relationship between GPS multipath observables and soil freeze/thaw process. One open GPS site and a corresponding SNOTEL soil climate site are analyzed to get the relationship between multipath SNR and soil temperature (as soil freeze/thaw process occurs). To take the effect of receiver temperature into consideration, multipath data at higher elevation angles are analyzed. In-situ measurement data indicate that there is a good relationship between soil temperature and GPS multipath data and there is a bright potential for soil freeze/thaw process detection using GNSS-IR.