Journal Article

Roles of the atmosphere and ocean in the projected north atlantic warming hole

Li, Qiuxian, Lu, Jian, Luo, Yiyong, Teng, Heli, Liu, Fukai

2024

Overview

There exists a warming deficit in sea surface temperatures (SST) over the subpolar North Atlantic in response to quadrupled CO 2 , referred to as the projected North Atlantic warming hole (WH). This study employs a partial coupling technique to accurately verify the relative roles of oceanic and atmospheric processes in the formation of the projected WH within an atmosphere-ocean coupled framework. By decomposing the SST anomalies in the subpolar North Atlantic into two components: those induced by atmospheric processes (i.e., the atmosphere-forced component) and those driven by changes in ocean circulation (i.e., the ocean-driven component), we find that the projected WH is primarily driven by changes in ocean circulation, with almost no contribution from atmospheric processes. Specifically, the slowdown of the Atlantic Meridional Overturning Circulation (AMOC) results in a cooling of SST in the WH region due to reduced northward ocean heat transport into this region. This study further quantifies the influence of a positive coupled feedback through surface heat flux (SHF) on the AMOC response under greenhouse gas forcing within this self-consistent framework. It is found that the AMOC slowdown leads to a negative SST anomaly in the subpolar North Atlantic and subsequently a positive ocean-driven SHF anomaly, which in turn further weakens the AMOC. This positive feedback through the SHF contributes about 50% to the total AMOC slowdown in response to quadrupled CO 2 .

• Publisher: Springer Berlin Heidelberg,Springer,Springer Nature B.V,Springer-Verlag
• Subject: Atlantic Meridional Overturning Circulation (AMOC) / Atmosphere / Atmospheric circulation / Atmospheric processes / Carbon dioxide / Climatology / cooling / Earth and Environmental Science / Earth Sciences / Environmental aspects / ENVIRONMENTAL SCIENCES / Feedback / Geophysics/Geodesy / Greenhouse effect / Greenhouse gases / Heat flux / Heat transfer / Heat transport / North Atlantic warming hole, Atlantic Meridional Overturning Circulation, Climate change, Positive feedback / Ocean circulation / Ocean currents / Ocean temperature / Ocean-atmosphere interaction / Oceanography / Oceans / Original Article / Positive feedback / Sea surface temperature / Sea surface temperature anomalies / Superhigh frequencies / Surface heat flux / Surface temperature / Water circulation