Abstract
Abstract.Radio-echo sounding techniques are very useful for fast profiling of seasonal snowpack. Ground-penetrating radar (GPR) is used widely for various cryospheric applications, such as snow/glacier depth estimation, snow layer identification and snow water equivalent assessment. The dielectric constant of snow is an important input parameter for the acquisition and interpretation of GPR data from the snowpack. In this study, snow dielectric constant was measured along with physical properties of snow using a snow fork operating at 1 GHz frequency. Experiments were conducted at field observatories of the Snow and Avalanche Study Establishment located in different Himalayan ranges: Patseo (Greater Himalayan range), Dhundhi and Solang (Pir Panjal range). Interseasonal spatial and temporal variations in snow dielectric constant and associated snowpack properties were analysed for five winter seasons (2010-14). The mean seasonal snow dielectric constant is higher at Dhundhi (1.82 ±0.02) than at Patseo (1.69 ±0.02). The measured snow dielectric constant was used to derive snow density and liquid-water content (LWC). A better correlation between snow dielectric constant and LWC is observed for high-density snow (>300kgm-3; R2 = 0.95) than for low-density snow (<200kgm-3; R2 = 0.73). Snow-fork-derived snow density was in good agreement with manually measured values. The snow dielectric constant database generated during this study can be used as a reference for various field applications of GPR in snow-related studies.
Highlights
Seasonal snow cover in the Indian Himalaya plays an important role in various cryospheric research processes of concern in climatology, glaciology, hydrology and avalanche studies
The snow dielectric constant, density and liquid-water content (LWC) were lowest for precipitation particles (1.21, 100 kg m–3, 0.15%) and highest for faceted snow crystals (1.44, 190 kg m–3, 5.35%)
It was observed that the dielectric constant, density and LWC were higher at Dhundhi than at Patseo
Summary
Seasonal snow cover in the Indian Himalaya plays an important role in various cryospheric research processes of concern in climatology, glaciology, hydrology and avalanche studies. There is large spatial and temporal variability in snowpack properties (e.g. dielectric constant, density and moisture content) in different Himalayan ranges due to the varying climate and terrain. Ground-penetrating radar (GPR), a non-destructive radio-echo sounding technique, is used to collect point values as well as the spatial distribution of snow properties. Various snow properties, such as depth distribution, identification of internal layer structures, and onset of wetness (Machguth and others, 2006; Heilig and others, 2010; Mitterer and others, 2011a; Singh and others, 2011; Schmid and others, 2014), have been acquired using GPR from ground and airborne platforms. The dielectric properties are important in the estimation of snow wetness, density, emissivity, albedo, etc. The dielectric properties are important in the estimation of snow wetness, density, emissivity, albedo, etc. from various satellite data (Armstrong, 1976; Warren and Wiscombe, 1985; Conway and Raymond, 1993; Gupta and others, 2005)
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