| || Albedo Variations and Surface Energy Balance in Different Snow-Ice Media in Antarctica
Author : Mishra, V.D.
Source : Defence Science Journal ; Vol:49(5) ; 1999 ; pp 347-362
Subject : 551 Geology
Keywords : Antartica;Albedo Variations;Energy Balance
Abstract : The present study is aimed at investigating the radiation budget in different snow-ice media (shelf ice, continental ice and natural snow) at three different elevated sites in the general area of Prince Astrid Coast of East Antarctica. Measurements of the dependence of albedo in different snow and ice media on solar elevation angle, cloud cover, liquid water content, grain size, etc. can be interpreted in terms of single and multiple scattering radiative transfer theory. Detailed albedo measurements were carried out during summer and winter in different snow and ice media in 1997-98 at different selected sites at Antarctica. The average albedo values were found to be high (90 per cent) in snow medium, moderate (83 per cent) in shelf ice and very low (50 per cent) in continental ice medium. The albedo was found to be a function of cloud amount, increasing with the amount and thickness. In white-out condition during blizzards, high albedo (average 83 per cent) was found as compared to clear sky day (76 per cent) and after blizzard (average 78 per cent). It showed dependence on the type and age of snow also. New snowfall over old snow displayed higher values (90 per cent) than older snow (70 per cent) and decreased with the ageof snow from 13- 16 per cent. Naturalmelt-water in snowpack increases from 1- 10 per cent, resulting in albedo decay from 7-10 per cent. As the minimum solar elevation angle in Antarctica goes to 3O, strong qualitative analyses have been ma e of the dependenceof albedo on the solar elevation angle. Albedo values showed diurnal hysteresis and m in values were found to be higher than evening values at the same angle of elevation. The dependence was 4 sligh or solar elevations during day time when 0 % 12-IS0, but became larger with low angles when 8 = 3-12'. Solar insolations were also calculated for different months in order to calculate short wave radiation absorbed by snow and ice media. Insolations in different months at different selected sites lie in the ranges 10-540 lnlday (August-October), 350-911 lnlday (November-December) and 190-755 lnlday (January-February). Net energy balance was calculted usingmodel and was found to benegativemost of the time.