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

Journal Article · Fri May 31 04:00:00 EDT 2024 · Climate Dynamics

DOI:https://doi.org/10.1007/s00382-024-07289-w· OSTI ID:2496211

Li, Qiuxian ^[1]; Luo, Yiyong ^[1]; Lu, Jian ^[2]; Liu, Fukai ^[1]; Teng, Heli ^[3]

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1. Ocean University of China, Qingdao (China)
2. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
3. National Satellite Ocean Application Service, Beijing (China)

There exists a warming deficit in sea surface temperatures (SST) over the subpolar North Atlantic in response to quadrupled CO₂, 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. In conclusion, this positive feedback through the SHF contributes about 50% to the total AMOC slowdown in response to quadrupled CO₂.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); National Natural Science Foundation of China (NSFC); Laoshan Laboratory; National Energy Research Scientific Computing Center (NERSC); Youth Innovation Team Program
• Grant/Contract Number: AC05-76RL01830; AC02-05CH11231
• OSTI ID: 2496211
• Report Number(s): PNNL-SA--191413
• Journal Information: Climate Dynamics, Journal Name: Climate Dynamics Journal Issue: 8 Vol. 62; ISSN 0930-7575
• Publisher: Springer-Verlag
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
North Atlantic warming hole
Atlantic Meridional Overturning Circulation
Climate change
Positive feedback
Sea surface temperature
Surface heat flux