The Shortwave Solar Radiation Energy Absorbed by Packed Sea Ice in the Central Arctic
Received date: 2008-11-28
Revised date: 2008-12-15
Online published: 2009-01-10
The solar energy is the main energy source to melt sea ice in the Arctic. The solar energy absorbed by the packed ice in the central Arctic is studied in this paper based on the optical observations of the Third Chinese Arctic Expedition on an ice camp during the period of August 21-27, 2008. The transmission, albedo, and the absorption rates of the sea ice and their variation with ice thickness are calculated from the observed data. On average, the absorption rate of sea ice for shortwave solar radiation is about 16%, meanwhile, about 77% of the incident energy is reflected back to the space. A three-day optical observation was conducted to determine the amount of the arriving solar radiation. Although the solar radiation arriving on the upper atmosphere was still strong in August, but about 57% of them was reduced by the atmosphere, as the coverage of cloud and fog caused obvious absorption to the shortwave radiation. Therefore, the heat flux absorbed by sea ice was only 10.2W/m2, corresponding to the heat in melting 2.6 mm ice per day or 1 m ice within 380 days. It means that the weak heat flux did not provide sufficient heat to melt the sea ice there. Therefore, the packed ice still covers the central Arctic Ocean even though the ice coverage becomes nearly the minimum in the whole Arctic. However, the result also indicated that some other factors, if appeared, could cause the increased melting of the packed ice, such as the decrease of cloud and fog, the total melting of snow layer, the reduction of ice thickness, and the increase of the ponds which could especially endanger the permanent packed ice. In the future, it is possible for the sea ice in central Arctic to collapse if more heat is absorbed under the condition different to that of the summer of 2008.
Key words： Arctic Ocean; Sea ice; Optical observation; Solar radiation; Heat absorption.
ZHAO Jinping , ZHANG Shugang , JIAO Yutian , LI Tao . The Shortwave Solar Radiation Energy Absorbed by Packed Sea Ice in the Central Arctic[J]. Advances in Earth Science, 2009 , 24(1) : 33 -41 . DOI: 10.11867/j.issn.1001-8166.2009.01.0033
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