Influence of Arctic Sea Ice on the Climate over East Asia and Western North Pacific

Abstract

A substantial amount of Arctic sea ice has diminished in recent decades. The melting rate was accelerated during the latest decade with several record-breaking sea ice area minimums. Such a decrease in sea ice plays a key role in Arctic climate change through the strong positive ice-temperature feedbacks. Considering the potential links between Arctic and mid-latitude weather induced by large-scale circulation changes, examining atmospheric responses related to the Arctic sea ice loss is essential for improving our understanding of climate change and seasonal weather prediction. Previous studies have suggested the existence of prolonged linkage between recent reduction in autumn Arctic sea ice and cold winters in the mid-latitude. Compared to the potential influence of autumn sea ice on winter atmospheric circulation, the linkage between sea ice melting and atmospheric circulation during summer has been less actively studied.

In this study, possible connections between the autumnal Arctic sea ice and both the following years winter and summertime atmospheric temperature in midlatitude are investigated using reanalysis data. Spatial characteristics of correlations between the Arctic sea ice area and midlatitude atmospheric temperature changed over a specific threshold value of autumn sea ice area (6.5 million km2). The results of correlation analysis demonstrate autumnal sea ice area is strongly correlated with February and July air temperature over the East Asia and Western North Pacific, only during the recent period (2007-2017). There are also marked decreases in the standard deviations of air temperature over same area during the recent period, compared to the past period (1980-2006). Sea surface temperature, which is suggested by the previous literatures for the possible factor holding the wintertime signal until following years summer, shows similar pattern with the correlation maps of air temperature. We do not attempt to address the detailed dynamical mechanisms to explain the exact physical processes accounting for the linkage. Rather we focus on documenting the observed signals, which may be a starting point for more sophisticated analysis.