Experimental investigation of dielectric properties of seasonal snow at field observatories in the northwest Himalaya

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.

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