Temporal Monitoring of the Soil Freeze-Thaw Cycles over a Snow-Covered Surface by Using Air-Launched Ground-Penetrating Radar

Abstract

Abstract:We tested an off-ground ground-penetrating radar (GPR) system at a fixed location over a bare agricultural field to monitor the soil freeze-thaw cycles over a snow-covered surface. The GPR system consisted of a monostatic horn antenna combined with a vector network analyzer, providing an ultra-wideband stepped-frequency continuous-wave radar. An antenna calibration experiment was performed to filter antenna and back scattered effects from the raw GPR data. Near the GPR setup, sensors were installed in the soil to monitor the dynamics of soil temperature and dielectric permittivity at different depths. The soil permittivity was retrieved via inversion of time domain GPR data focused on the surface reflection. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and dielectric permittivity measurements. In particular, five freeze and thaw events were clearly detectable, indicating that the GPR signals respond to the contrast between the dielectric permittivity of frozen and thawed soil. The GPR-derived permittivity was in good agreement with sensor observations. Overall, the off-ground nature of the GPR Remote Sens. 2015, 7 12042 system permits non-invasive time-lapse observation of the soil freeze-thaw dynamics without disturbing the structure of the snow cover. The proposed method shows promise for the real-time mapping and monitoring of the shallow frozen layer at the field scale.

Spatiotemporal Variations in Snow and Soil Frost—A Review of Measurement Techniques

“…The radar can be operated from vehicles, such as helicopters, airplanes or snow mobiles and can thus cover large lateral distances in short times, or it can be mounted stationary and monitor temporal changes [61]. GPR-techniques have been applied to determine the spatial distribution of snow depths [74][75][76][77][78], snow density [77,79], SWE [80], snow layering and stratigraphy [78,81,82], wet snow properties [83], soil frost depth [84][85][86][87], depths to thawing front and shallow freeze and thaw processes [85,86,[88][89][90][91][92], soil water content [93,94] and depths to the water table [95,96].…”

“…Field scale shallow soil moisture profiles using full-waveform inversion of GPR data were mapped [102], and Jadoon et al [91] monitored temporal variations in freeze-thaw cycles on a snow covered agricultural field using a stationary mounted step-frequency radar and judged the method promising for real-time mapping of soil frost at the field scale. Steelman and Endres [85] used the development of high-frequency GPR direct ground wave propagation and could detect thinner frozen layers than when using the radar wave reflection from the frozen-unfrozen boarder.…”

Laboratory Testing to Research the Micro-Structure and Dynamic Characteristics of Frozen–Thawed Marine Soft Soil

“…Engineered freezing-thawing soils are different from freezing-thawing soils in nature [1][2][3][4]. The phase changes between liquid and solid water in soil during a freeze-thaw period have been studied previously [5].…”

The Influence of Geostatistical Prior Modeling on the Solution of DCT-Based Bayesian Inversion: A Case Study from Chicken Creek Catchment

“…This near-surface environment is highly heterogeneous and comprised of a rich biodiversity of living organisms, which interact with rock, soil, and water to regulate the natural habitat and determine the availability of nutrients and other life-sustaining resources. Electromagnetic (EM) geophysical methods provide a wealth of information about the subsurface electrical properties and are particularly well-suited for in situ measurement and monitoring of variables such as electrical conductivity (σ or EC (mS/m)) and permittivity [1,[4][5][6][7]. These data are of great value to water quality and water resource studies and key input to (hydro)geophysical models that simulate the flow, storage, and distribution of fluids in the subsurface [3,7,8].…”