Snow water equivalent recovery from laterally unconstrained aerial ground-penetrating radar

2020 ◽  
Author(s):  
Jonah Bartrand ◽  
John Bradford
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Water Equivalent ◽  
Snow Water ◽  
Ground Penetrating

scholarly journals Estimating snow water equivalent over long mountain transects using snowmobile-mounted ground-penetrating radar

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA183-WA193 ◽  
Author(s):  
W. Steven Holbrook ◽  
Scott N. Miller ◽  
Matthew A. Provart
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Water Equivalent ◽  
Ground Surface ◽  
Snow Accumulation ◽  
Accurate Estimation ◽  
Snow Density ◽  
Snow Stratigraphy ◽  
Flood Estimation ◽  
Snow Water ◽  
Ground Penetrating

The water balance in alpine watersheds is dominated by snowmelt, which provides infiltration, recharges aquifers, controls peak runoff, and is responsible for most of the annual water flow downstream. Accurate estimation of snow water equivalent (SWE) is necessary for runoff and flood estimation, but acquiring enough measurements is challenging due to the variability of snow accumulation, ablation, and redistribution at a range of scales in mountainous terrain. We have developed a method for imaging snow stratigraphy and estimating SWE over large distances from a ground-penetrating radar (GPR) system mounted on a snowmobile. We mounted commercial GPR systems (500 and 800 MHz) to the front of the snowmobile to provide maximum mobility and ensure that measurements were taken on pristine snow. Images showed detailed snow stratigraphy down to the ground surface over snow depths up to at least 8 m, enabling the elucidation of snow accumulation and redistribution processes. We estimated snow density (and thus SWE, assuming no liquid water) by measuring radar velocity of the snowpack through migration focusing analysis. Results from the Medicine Bow Mountains of southeast Wyoming showed that estimates of snow density from GPR ([Formula: see text]) were in good agreement with those from coincident snow cores ([Formula: see text]). Using this method, snow thickness, snow density, and SWE can be measured over large areas solely from rapidly acquired common-offset GPR profiles, without the need for common-midpoint acquisition or snow cores.

Field evaluation of a new method for estimation of liquid water content and snow water equivalent of wet snowpacks with GPR

2012 ◽  
Vol 44 (4) ◽  
pp. 600-613 ◽  
Author(s):  
Nils Sundström ◽  
David Gustafsson ◽  
Andrey Kruglyak ◽  
Angela Lundberg
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Snow Water Equivalent ◽  
Field Evaluation ◽  
Liquid Water Content ◽  
Snow Water ◽  
The Mean ◽  
Path Dependent ◽  
Ground Penetrating

Estimates of snow water equivalent (SWE) with ground-penetrating radar can be used to calibrate and validate measurements of SWE over large areas conducted from satellites and aircrafts. However, such radar estimates typically suffer from low accuracy in wet snowpacks due to a built-in assumption of dry snow. To remedy the problem, we suggest determining liquid water content from path-dependent attenuation. We present the results of a field evaluation of this method which demonstrate that, in a wet snowpack between 0.9 and 3 m deep and with about 5 vol% of liquid water, liquid water content is underestimated by about 50% (on average). Nevertheless, the method decreases the mean error in SWE estimates to 16% compared to 34% when the presence of liquid water in snow is ignored and 31% when SWE is determined directly from two-way travel time and calibrated for manually measured snow density.

scholarly journals On measuring snow ablation rates in alpine terrain with a mobile GPR device

2017 ◽  
Author(s):  
Nena Griessinger ◽  
Franziska Mohr ◽  
Tobias Jonas
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Depth ◽  
Snow Water Equivalent ◽  
Winter Season ◽  
Repeated Measurements ◽  
Swiss Alps ◽  
Promising Technique ◽  
Snow Water ◽  
Ground Penetrating ◽  
Good Agreement

Abstract. Ground penetrating radar (GPR) has become a promising technique in the field of snow hydrological research. It is commonly used to measure snow depth, density, and water equivalent over large distances or along gridded snow courses. Having built and tested a mobile light-weight setup, we demonstrate that GPR is capable of accurately measuring snow ablation rates in complex alpine terrain. Our setup was optimized for efficient measurements and consisted of a common-mid-point assembly with four pairs of antennas mounted to a plastic sled, which was small enough to permit safe and convenient operations. Repeated measurements were taken during the 2014/15 winter season along ten profiles within two valleys located in the eastern Swiss Alps. Resulting GPR-based data of snow depth and water equivalent as well as their respective change rates over time were in good agreement with concurrent manual measurements, in particular if accurate alignment between repeated overpasses could be achieved (root-mean-square error of 4.5 cm for snow depth, 25 mm for snow water equivalent, and 4.4 cm and 26 mm for the respective change rates). With its suitability for alpine terrain and the achieved accuracy, the presented setup could become a valuable tool to validate snowmelt models or to complement lidar-based snow surveys.

A critical analysis on the uncertainty computation in ground-penetrating radar-retrieved dry snow parameters

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. H39-H49
Author(s):  
Federico Di Paolo ◽  
Barbara Cosciotti ◽  
Sebastian E. Lauro ◽  
Elisabetta Mattei ◽  
Elena Pettinelli
Keyword(s):  
Wave Velocity ◽  
Ground Penetrating Radar ◽  
Snow Water Equivalent ◽  
Radar Data ◽  
Published Data ◽  
Physical Parameters ◽  
Large Area ◽  
Essential Information ◽  
Two Parameters ◽  
Ground Penetrating

The use of the ground-penetrating-radar (GPR) technique to estimate snow parameters such as thickness, density, and snow water equivalent (SWE) is particularly promising because it allows for surveying a large area in a relatively short amount of time. However, this application requires an accurate evaluation of the physical parameters retrieved from the radar measurements, which requires estimating each quantity involved in the computation along with its associated uncertainty. Conversely, the uncertainties are rarely reported in GPR snow studies, even if they represent essential information for data comparisons with other techniques such as the snow rod or snow pit methods. Snow parameters can be estimated from radar data as follows: The snow thickness can be computed from two-way traveltime if the snow average wave velocity is known; the snow density can be estimated from wave velocity using an appropriate mixing formula, and SWE can be computed once these two parameters have been calculated. Starting from published data, we have estimated the accuracy achievable by computing the overall uncertainty for each GPR-retrieved snow parameter and evaluated the influence of the different sources of uncertainties. The computation was made for three antenna frequencies (250, 500, and 1000 MHz) and various snow depths (0–5 m). We find that for snow thicknesses of less than 3 m, the main contribution to the uncertainties associated with snow parameters is given by the uncertainty on two-way traveltime estimation, especially for low antenna frequencies. However, for thicker snow depths, other factors such as the uncertainty on the antenna separation affect the overall accuracy and cannot be neglected. Our studies highlight the importance of the uncertaintiy assessment and suggest a rigorous way for their computation in the field of quantitative geophysics.

scholarly journals Continuous snowpack monitoring using upward-looking ground-penetrating radar technology

2014 ◽  
Vol 60 (221) ◽  
pp. 509-525 ◽  
Author(s):  
Lino Schmid ◽  
Achim Heilig ◽  
Christoph Mitterer ◽  
Jürg Schweizer ◽  
Hansruedi Maurer ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Water Equivalent ◽  
Temporal Evolution ◽  
Liquid Water Content ◽  
Internal Layers ◽  
Contributing Factors ◽  
Height Measurement ◽  
Additional Information ◽  
Snow Properties ◽  
Ground Penetrating

AbstractSnow stratigraphy and water percolation are key contributing factors to avalanche formation. So far, only destructive methods can provide this kind of information. Radar technology allows continuous, non-destructive scanning of the snowpack so that the temporal evolution of internal properties can be followed. We installed an upward-looking ground-penetrating radar system (upGPR) at the Weissfluhjoch study site (Davos, Switzerland). During two winter seasons (2010/11 and 2011/12) we recorded data with the aim of quantitatively determining snowpack properties and their temporal evolution. We automatically derived the snow height with an accuracy of about ± 5 cm, tracked the settlement of internal layers (± 7 cm) and measured the amount of new snow (± 10 cm). Using external snow height measurements, we determined the bulk density with a mean error of 4.3% compared to manual measurements. Radar-derived snow water equivalent deviated from manual measurements by 5%. Furthermore, we tracked the location of the dry-to-wet transition in the snowpack until water percolated to the ground. Based on the transition and an independent snow height measurement it was possible to estimate the volumetric liquid water content and its temporal evolution. Even though we need additional information to derive some of the snow properties, our results show that it is possible to quantitatively derive snow properties with upGPR.

scholarly journals Spatial patterns of snow accumulation across Belcher Glacier, Devon Ice Cap, Nunavut, Canada

2013 ◽  
Vol 59 (217) ◽  
pp. 874-882 ◽  
Author(s):  
Tyler Sylvestre ◽  
Luke Copland ◽  
Michael N. Demuth ◽  
Martin Sharp
Keyword(s):  
Snow Water Equivalent ◽  
Snow Accumulation ◽  
Center Frequency ◽  
Neutron Density ◽  
Rain Event ◽  
Ice Cap ◽  
Devon Ice Cap ◽  
Snow Water ◽  
The 1960S ◽  
Ground Penetrating

AbstractGround-penetrating radar (GPR) surveys at a center frequency of 500 MHz were used to determine winter (2007/08) and net annual (2005–07) snow water equivalent (SWE) patterns across the upper parts of Belcher Glacier, Devon Ice Cap, Nunavut, Canada. The GPR measurements were validated against snow depths determined from avalanche probe measurements, and converted to SWE values using densities measured with a down-borehole neutron density probe and in shallow snow pits. Distinct internal reflection horizons (IRHs) in the GPR record were formed during warm summers in 2007 and 2005, and a large rain event in summer 2006 which caused ice to accumulate above the 2005 melt surface. Elevation provides the dominant control on winter SWE distribution across the basin, with surface topography (e.g. gullies) also being locally important. Based on the location where IRHs intersected the ice-cap surface, the basin-wide firn line occurred at an altitude of 1260–1300 m over the period 2005–08. Net mass balance across the accumulation area of Belcher Glacier averaged 0.24 m w.e. a−1 over the period 2005–07, mainly dependent on altitude. This is a little higher than most previous estimates for the period since the 1960s, although the differences lie within error limits.

scholarly journals In Situ Determination of Dry and Wet Snow Permittivity: Improving Equations for Low Frequency Radar Applications

2021 ◽  
Vol 13 (22) ◽  
pp. 4617
Author(s):  
Ryan W. Webb ◽  
Adrian Marziliano ◽  
Daniel McGrath ◽  
Randall Bonnell ◽  
Tate G. Meehan ◽  
...  
Keyword(s):  
Snow Water Equivalent ◽  
Low Frequency ◽  
Liquid Water Content ◽  
Seasonal Snow ◽  
Wet Snow ◽  
Primary Driver ◽  
Snow Water ◽  
Snow Conditions ◽  
Ground Penetrating

Extensive efforts have been made to observe the accumulation and melting of seasonal snow. However, making accurate observations of snow water equivalent (SWE) at global scales is challenging. Active radar systems show promise, provided the dielectric properties of the snowpack are accurately constrained. The dielectric constant (k) determines the velocity of a radar wave through snow, which is a critical component of time-of-flight radar techniques such as ground penetrating radar and interferometric synthetic aperture radar (InSAR). However, equations used to estimate k have been validated only for specific conditions with limited in situ validation for seasonal snow applications. The goal of this work was to further understand the dielectric permittivity of seasonal snow under both dry and wet conditions. We utilized extensive direct field observations of k, along with corresponding snow density and liquid water content (LWC) measurements. Data were collected in the Jemez Mountains, NM; Sandia Mountains, NM; Grand Mesa, CO; and Cameron Pass, CO from February 2020 to May 2021. We present empirical relationships based on 146 snow pits for dry snow conditions and 92 independent LWC observations in naturally melting snowpacks. Regression results had r2 values of 0.57 and 0.37 for dry and wet snow conditions, respectively. Our results in dry snow showed large differences between our in situ observations and commonly applied equations. We attribute these differences to assumptions in the shape of the snow grains that may not hold true for seasonal snow applications. Different assumptions, and thus different equations, may be necessary for varying snowpack conditions in different climates, suggesting that further testing is necessary. When considering wet snow, large differences were found between commonly applied equations and our in situ measurements. Many previous equations assume a background (dry snow) k that we found to be inaccurate, as previously stated, and is the primary driver of resulting uncertainty. Our results suggest large errors in SWE (10–15%) or LWC (0.05–0.07 volumetric LWC) estimates based on current equations. The work presented here could prove useful for making accurate observations of changes in SWE using future InSAR opportunities such as NISAR and ROSE-L.

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