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. ; R 2 = 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.

In this study an airborne ground penetrating radar (GPR) is used to estimate spatial distribution of snow accumulation in the Samudra Tapu glacier (the Great Himalayan Range), Western Himalaya, India. An impulse radar system with 350 MHz antenna was mounted on a helicopter for the estimation of snow depth. The dielectric properties of snow were measured at a representative site (Patseo Observatory) using a snow fork to calibrate GPR data. The snow depths estimated from GPR signal were found to be in good agreement with those measured on ground with an absolute error of 0.04 m. The GPR survey was conducted over Samudra Tapu glacier in March 2009 and 2010. A kriging-based geostatistical interpolation method was used to generate a spatial snow accumulation map of the glacier with the GPR-collected data. The average accumulated snow depth and snow water equivalent (SWE) for a part of the glacier were found to be 2.23 m and 0.624 m for 2009 and 2.06 m and 0.496 m for 2010 respectively. Further, the snow accumulation data were analysed with various topographical parameters such as altitude, aspect and slope. The accumulated snow depth showed good correlation with altitude, having correlation coefficient varying between 0.57 and 0.84 for different parts of the glacier. Higher snow accumulation was observed in the north-and east-facing regions, and decrease in snow accumulation was found with an increase in the slope of the glacier. Thus, in this study we generate snow accumulation/SWE information using airborne GPR in the Himalayan terrain.Keywords: Glacier, ground penetrating radar, snow accumulation, snow water equivalent.IN the Himalaya snow and glaciers cover a large geographical area and influence climate and environment of the region. Recent studies carried out using satellite images suggest approximately 40,800 sq. km area is covered by glaciers in the Great Himalaya and Karakoram mountain ranges 1 . These glaciers are a perennial and vital source of freshwater to the countries around the Himalayan chain. In recent years, glaciers and seasonal snow cover in this region have been significantly influenced by climate change 2-7 ; therefore, it is useful to monitor the spatial and temporal changes of snow thickness.Estimation of snow thickness using field-based methods such as snow stakes, automatic sensors, etc. provides mostly point-specific information. However, ground penetrating radar (GPR), a non-destructive technique, can be used to collect both point as well as spatial distribution of snow thickness. It has been widely used in ground mode, for snow and ice thickness measurements [8][9][10][11][12][13][14][15] , snowpack stratigraphic delineation 16 and to study the subsurface properties of other strata 17 . Forte et al. 18,19 reported the applications of GPR data in determining the density and electromagnetic (EM) wave velocity for snow, firn and ice. Colucci et al. 20 used GPR profiles in combination with LiDAR data to calculate the volumetric and mass variations in the body of the ice. Apart from ground...

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