Revisiting the Linkages between the Variability of Atmospheric Circulations and Arctic Melt-Season Sea Ice Cover at Multiple Time Scales

Abstract

<p>The sharp decline of Arctic sea ice in recent decades has captured the attention of the climate science<br>community. A majority of climate analyses performed to date have used monthly or seasonal data. Here,<br>however, we analyze daily sea ice data for 1979–2016 using the self-organizing map (SOM) method to further<br>examine and quantify the contributions of atmospheric circulation changes to the melt-season Arctic sea ice<br>variability. Our results reveal two main variability modes: the Pacific sector mode and the Barents and Kara<br>Seas mode, which together explain about two-thirds of the melt-season Arctic sea ice variability and more<br>than 40% of its trend for the study period. The change in the frequencies of the two modes appears to be<br>associated with the phase shift of the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation<br>(AMO). The PDO and AMO trigger anomalous atmospheric circulations, in particular, the<br>Greenland high and the North Atlantic Oscillation and anomalous warm and cold air advections into the<br>Arctic Ocean. The changes in surface air temperature, lower-atmosphere moisture, and downwelling longwave<br>radiation associated with the advection are consistent with the melt-season sea ice anomalies observed<br>in various regions of the Arctic Ocean. These results help better understand the predictability of Arctic sea ice<br>on multiple (synoptic, intraseasonal, and interannual) time scales.</p>