Abstract
Abstract. Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents–Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents–Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.
Highlights
Warming over the Arctic Ocean is observed to accelerate in recent decades
Northern hemispheric (30–90◦ N) 2 m air temperature is used as the target variable, since polar amplification in the Northern Hemisphere is clearly identified as the leading mode in 2 m air temperature aside from the seasonal cycle
Sea ice loss is confined to the Barents–Kara seas in winter, where turbulent heat flux is significantly increased. It seems that the increased solar radiation as a result of albedo feedback is responsible for the sea ice loss and sea surface warming in summer, except for the western part of the Barents Sea, where sea surface warming seems associated with oceanic heat transport
Summary
Warming over the Arctic Ocean is observed to accelerate in recent decades. The rate of warming in the Arctic is more than twice the rate of globally averaged warming. When sea surface remains to be free of ice in winter, turbulent heat flux is released from the open ocean surface, which is instrumental for warming the lower troposphere (Francis et al, 2009; Serreze et al, 2009; Screen and Simmonds, 2010a, b; Deser et al, 2010; Overland et al, 2011; Serreze and Barry, 2011; Cohen et al, 2014; Screen et al, 2014) According to this hypothesis, increased reception of insolation through the sea surface exposed to air in summer keeps the sea surface warmer and is released in fall and early winter, making the atmosphere warmer. The rate of acceleration of the Arctic amplification is estimated based on CSEOF analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
