North Pacific Gyre Oscillation Closely Associated With Spring Arctic Sea Ice Loss During 1998–2016.

The relative importance of the factors contributing to Arctic spring sea ice decline remains an open question. Here we suggest a new major factor. In spring the North Pacific Gyre Oscillation (NPGO) shows a significantly increasing trend during 1998–2016, in contrast to the insignificant trend of the Pacific Decadal Oscillation (PDO) index. Nearly 40% of Arctic springtime sea ice concentration trend is statistically related to the increase of the NPGO index but only 4% to the PDO trend. Through the destructive linear interference with climatological Aleutian low, the increasing NPGO index tends to weaken the upward propagation of planetary waves, which enhances the strength of the stratospheric Arctic vortex and the Arctic Oscillation (AO). The positive AO anomalies influence the surface wind field and temperature pattern anomalies, contributing to negative sea ice anomalies in the Arctic. Key Points: An increase in the NPGO index for the 1998–2016 period statistically explains nearly 40% of Arctic springtime sea ice lossThe increasing NPGO index produces an anomalous high, weakening climatological Aleutian low and the upward propagation of planetary wavesThe weakened upward propagated waves strengthen the stratospheric vortex and the Arctic Oscillation, which lead to reduced Arctic sea ice [ABSTRACT FROM AUTHOR]