Abstract
Sea ice reduction is accelerating in the Barents and Kara Seas. Several mechanisms are proposed to explain the accelerated loss of Arctic sea ice, which remains to be controversial. In the present study, detailed physical mechanism of sea ice reduction in winter (December–February) is identified from the daily ERA interim reanalysis data. Downward longwave radiation is an essential element for sea ice reduction, but can primarily be sustained by excessive upward heat flux from the sea surface exposed to air in the region of sea ice loss. The increased turbulent heat flux is used to increase air temperature and specific humidity in the lower troposphere, which in turn increases downward longwave radiation. This feedback process is clearly observed in the Barents and Kara Seas in the reanalysis data. A quantitative assessment reveals that this feedback process is being amplified at the rate of ~8.9% every year during 1979–2016. Availability of excessive heat flux is necessary for the maintenance of this feedback process; a similar mechanism of sea ice loss is expected to take place over the sea-ice covered polar region, when sea ice is not fully recovered in winter.
Highlights
Due to the large seasonal variation of insolation, there exists pronounced seasonality in the air-sea interaction process over the Arctic Ocean
Despite the general consensus that heat transfer between the ocean and atmosphere is a crucial element in the physical mechanism of Arctic amplification and sea ice reduction, a quantitative understanding of individual contributions of heat flux components is still controversial
In the previous study[33], we showed that the temporal pattern of sea ice variation differs significantly between the Barents–Kara Seas and the Laptev and Chukchi Seas
Summary
Kwang-Yul Kim[1], Ji-Young Kim 1, Jinju Kim[1], SaerimYeo[2], Hanna Na 1, Benjamin D. A quantitative assessment of energy fluxes involved in the Arctic amplification is investigated in relation to the sea ice reduction over the Barents and Kara Seas This is an extension of the previous study with a specific goal of delineating the feedback mechanism between sea surface and the atmosphere. We extract a physically meaningful warming signal in the Arctic region and investigate how sea ice loss and individual energy fluxes are linked in a quantitative manner For this goal, cyclostationary empirical orthogonal function (CSEOF) analysis[38,39,40] is carried out on surface and pressure-level variables derived from the ERA interim daily reanalysis data[41] in winter (Dec. 1–Feb. 28, d = 90 days). It should be noted that our discussion is restricted to processes in the Arctic; forcing from lower latitudes can be important in the process of Arctic amplification and sea ice reduction
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