Session: Warm Climates (Mid-Holocene, Last interglacial, Deep-time, Pliocene)
Author: Qiong Zhang / email@example.com / Stockholm University
Co-author: Jianqiu Zheng, University of science and technology of China; Stockholm University;
Qiang Li, Stockholm University;
Qiang Zhang, Stockholm University;
Arctic sea-ice extent minimum have been refreshed frequently over the last decade. As the sea ice retreats, its reflectivity and insulation decrease. This leads to the changes in surface heat budget directly or indirectly through overlying cloud and water vapour. In this work, the Pliocene simulation with EC-Earth climate model is performed as an analogue for future climate projections. The EC-Earth Pliocene simulation shows a strong Arctic amplification featured by pronounced warming SST over North Atlantic in particular over Greenland Sea and Baffin Bays, which is comparable with geological SST reconstructions documented in Dowsett et al. (2012). In order to reveal underlying physical processes, the air-sea heat flux variation in response to Arctic sea ice change is quantitatively assessed by a climate feedback and response analysis method (CFRAM) and an equilibrium feedback assessment (EFA)-like approach. Our analyses show that the albedo effect is dominant in summer, a 1% decrease in sea ice concentration could lead to an approximate 2 Wm-2 increase in short wave solar radiation through open sea surface. The insulation effect is attributed mainly to turbulent heat flux, which releases heat from the ocean to atmosphere prominently in winter. The sea ice decline accelerates the turbulent exchange between the ocean and atmosphere. We found that insulation effect in winter is slightly stronger than albedo effect in summer, thus explains the stronger warming amplification in winter than in summer.