Change in Sea Ice Cover is Responsible for Non-Uniform Variation in Winter Temperature over East Asia

Abstract

AbstractObserved winter (December—February) surface air temperature over East Asia (0°–60°N, 100–140°E) (TEA) shows non-uniform variation during 1979–2013, with cooling and weak warming north and south of 40°N. To understand this, the authors perform statistical analysis (linear regression and composite) on the observed data. The results suggest that reduced (increased) autumn sea ice cover in the Barents-Kara Sea (BK-ASIC) lowers (warms) TEA over northern East Asia, which is consistent with previous studies. In comparison, increased (decreased) winter sea ice cover in the Sea of Okhotsk (O-WSIC), warms (cools) the air over southern East Asia. The mechanism can be described as follows: When the BK-ASIC decreases, the East Asian winter monsoon tends to be stronger with an intensified Siberian high, leading to cooling over northern East Asia. An O-WSIC increase is associated with cold anomalies north of 50°N, altering the meridional temperature gradient between the midlatitudes and tropics, and leading to a...