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 Retrieval of Snow Water Equivalent, Liquid Water Content, and Snow Height of Dry and Wet Snow by Combining GPS Signal Attenuation and Time Delay

2019 ◽  
Vol 55 (5) ◽  
pp. 4465-4487 ◽  
Author(s):  
Franziska Koch ◽  
Patrick Henkel ◽  
Florian Appel ◽  
Lino Schmid ◽  
Heike Bach ◽  
...  
Keyword(s):  
Time Delay ◽  
Water Content ◽  
Liquid Water ◽  
Snow Water Equivalent ◽  
Liquid Water Content ◽  
Signal Attenuation ◽  
Wet Snow ◽  
Snow Water

Snow Wetness Influence on Impulse Radar Snow Surveys Theoretical and Laboratory Study

2000 ◽  
Vol 31 (2) ◽  
pp. 89-106 ◽  
Author(s):  
A. Lundberg ◽  
H. Thunehed
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Snow Water Equivalent ◽  
Liquid Water Content ◽  
Late Winter ◽  
Propagation Time ◽  
Reservoir Water ◽  
A Value ◽  
Wet Snow ◽  
Snow Water

The snow-water equivalent of late-winter snowpack is of utmost importance for hydropower production in areas where a large proportion of the reservoir water emanates from snowmelt. Impulse radar can be used to estimate the snow-water equivalent of the snowpack and thus the expected snowmelt discharge. Impulse radar is now in operational use in some Scandinavian basins. With radar technology the radar wave propagation time in the snowpack is converted into snow-water equivalent with help of a parameter usually termed the a-value. Use of radar technology during late winter brings about risk for measurements on wet snow. The a-value for dry snow cannot be used directly for wet snow. We have found that a liquid-water content of 5% (by volume) reduces the a-value by approximately 20%. In this paper an equation, based on snow density and snow liquid water content, for calculation of wet-snow a-value is presented.

scholarly journals Microwave Measurements of Snowpack Properties

1981 ◽  
Vol 12 (3) ◽  
pp. 143-166 ◽  
Author(s):  
W.H. Stiles ◽  
F.T. Ulaby ◽  
A. Rango
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Snow Water Equivalent ◽  
Liquid Water Content ◽  
Microwave Measurements ◽  
Data Sets ◽  
Microwave Response ◽  
Passive Data ◽  
Snow Water ◽  
Snowpack Properties

Prior microwave measurements of snow water equivalent and liquid water content and conceptualizations of emission and backscattering models are reviewed. The results of an experiment designed to collect simultaneous passive and active microwave data to be used in interpreting and analyzing the sensitivity of the microwave spectrum to changing snowpack properties are reported. Both the scattering coefficient, σ°, and the apparent radiometric temperature, Tap, were found to be sensitive to changes in snow water equivalent and liquid water content. The σ° data exhibit an exponential-like increase with increasing water equivalent, whereas, the Tap data exhibit an exponential-like decrease. For both the active and passive data, the snow water equivalent at which the microwave response begins to saturate decreases as the wavelength decreases. Increasing liquid water in the snowpack causes a decrease in σ° and an increase in the Tap. Diurnal data sets show the greatest σ° and Tap variation in response to snowmelt at 35 and 37 GHz with correspondingly less variation at the lower frequencies. Based on research results to date, immediate formulation of a comprehensive microwave and snow research program is recommended.

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.

scholarly journals Imaging the structure of cave ice by ground-penetrating radar

2011 ◽  
Vol 5 (2) ◽  
pp. 329-340 ◽  
Author(s):  
H. Hausmann ◽  
M. Behm
Keyword(s):  
Electromagnetic Wave ◽  
Internal Structure ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Speed ◽  
Liquid Water Content ◽  
Thin Layers ◽  
Ice Formation ◽  
Alpine Regions ◽  
Ground Penetrating

Abstract. Several caves in high elevated alpine regions host up to several meters thick ice. The age of the ice may exceed some hundreds or thousands of years. However, structure, formation and development of the ice are not fully understood and are subject to relatively recent investigation. The application of ground-penetrating radar (GPR) enables to determine thickness, volume, basal and internal structure of the ice and provides as such important constraints for related studies. We present results from four caves located in the Northern Calcareous Alps of Austria. We show that the ice is far from being uniform. The base has variable reflection signatures, which is related to the type and size of underlying debris. The internal structure of the cave ice is characterized by banded reflections. These reflection signatures are interpreted as thin layers of sediments and might help to understand the ice formation by representing isochrones. Overall, the relatively low electromagnetic wave speed suggests that the ice is temperate, and that a liquid water content of about 2% is distributed homogenously in the ice.

scholarly journals A portable calorimeter for measuring liquid-water content of wet snow

1998 ◽  
Vol 26 ◽  
pp. 103-106 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Toru Endo ◽  
Yukari Takeuchi
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Total Weight ◽  
Light Weight ◽  
High Mountains ◽  
Insulating Materials ◽  
Wet Snow ◽  
Snow Water

In order to facilitate the measurement of liquid-water content of snow in high mountains, a portable calorimeter named “Endo-type snow-water content meter” was developed. It is composed of a metal-coated container made of insulating materials and a lid of the container with a small-thermistor thermometer. Its strong points are its light weight, small size and easy fabrication with cheap materials. The total weight of the device is as light as 250 g, which is less than 10% of the snow-water content meter widely used in Japan (Akitaya-type snow-water content meter). The results of experiments have revealed that the device is capable of measuring the liquid-water content within 2 minutes with an accuracy of 2% by weight.

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.

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