Soil Moisture and Soil Depth Retrieval Using the Coupled Phase-Amplitude Behavior of C-Band Radar Backscatter in the Presence of Sub-Surface Scattering. Issue 6 (2nd November 2022)

• Record Type: Journal Article
• Authors: Morrison, Keith; Wagner, Wolfgang
• Is Part Of: Canadian journal of remote sensing. Volume 48:Issue 6(2022)
• Page Start: 779
• Page End: 792
• Publication Date: 2022-11-02
• Subjects: Remote sensing -- Periodicals; 621.367805
• DOI: 10.1080/07038992.2022.2120858
• Languages: English
• ISSNs: 0703-8992

Abstract

Abstract: In low-moisture regimes, strongly-reflecting bedrock underlying soil could provide a dominant return. This offers a novel opportunity to retrieve both the volumetric moisture fraction ( mv ) and depth ( d ) of a soil layer using a differential phase. A radar wave traversing the overlying soil slows in response to moisture state; moisture dynamics are thus recorded as variations in travel time—captured back at a radar platform as changes in phase. The Phase Scaled Dielectric (PSD) model introduced here converts phase changes to those in soil dielectric as an intermediate step to estimating mv . Simulations utilizing a real soil moisture timeseries from a site in Sudan were used to demonstrate the linked behaviors of the soil and radar variables, and detail the PSD principle. A laboratory validation used soil with a wet top layer variable in depth 1–2 cm and drying from mv ∼ 0.2 m 3 m −3, overlying a gravel layer at a depth of 11 cm. The scheme retrieved d = 1.49 ± 0.33 cm and a change Δ mv = 0.191–0.021 ± 0.009 m 3 m −3 . The PSD scheme outlined here promises a new avenue for the diagnostic measurement of soil parameters which is not currently available to radar remote sensing.