P K Satyawali
Articles written in Journal of Earth System Science
Volume 117 Issue 4 August 2008 pp 465-475
A geometrical model,including different geometrical shapes in ﬂuencing thermal conductivity of snow is proposed.The geometrical model has been assumed to comprise of unit cells having solid (ice)inclusion as an aggregation of spherical,cylindrical or cubical shapes with vertical connection, arranged in a cubic packing.From the geometrical model and one-dimensional heat transfer theory, the effective thermal conductivity has been computed.For this purpose,coupled one-dimensional heat transfer equations have been solved for steady-state condition to account for conduction in ice, conduction in air and latent heat transfer due to water vapour sublimation through air.The model demonstrates the dependency of thermal conductivity on density,grain-spacing,grain contact ratio and temperature.Spherical inclusions give highest conductivity while cubical inclusion estimates lowest value for the same density.Thermal conductivity has been found increasing sharply near to the packing density for all three shapes.Empirical model results and results obtained from existing microstructure based models have also been compared with the present model.
Volume 117 Issue 5 October 2008 pp 567-573
This study describes time series analysis of snow-melt,radiation data and energy balance for a seasonal snow cover at Dhundi ﬁeld station of SASE,which lies in Pir Panjal range of the N –W Himalaya,for a winter season from 13 January to 12 April 2005.The analysis shows that mean snow surface temperature remains very close to the melting temperature of snow.It was found close to -1°C for the complete observational period which makes the snow pack at Dhundi moist from its beginning.The average air temperature over this period was found to be 3.5°C with hourly average variation from -5.5°C to 13°C. The snow surface at this station received a mean short wave radiation of 430 W m−2, out of which 298 W m−2 was re ﬂected back by the snow surface with mean albedo value of 0.70. The high average temperature and more absorption of solar radiation resulted in higher thermal state of the snowpack which was further responsible for faster and higher densiﬁcation of the snowpack. Net radiation energy was the major component of surface energy budget with a mean value of 83 W m−2. Bulk transfer model was used to calculate turbulent ﬂuxes. The net energy was utilized for satisfying cold content and snow-melt by using measured snow surface temperature and density of snow pack. The mean square error between calculated and measured daily snow-melt was found to be approximately 6.6 mm of water equivalent.
Volume 128 | Issue 8
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