caa a22 4500 605472521 CHVBK 20210128100338.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00382-015-2534-0 doi (NATIONALLICENCE)springer-10.1007/s00382-015-2534-0 A process-based analysis of ocean heat uptake in an AOGCM with an eddy-permitting ocean component [Elektronische Daten] [T. Kuhlbrodt, J. Gregory, L. Shaffrey] About 90% of the anthropogenic increase in heat stored in the climate system is foundin the oceans. Therefore it is relevant to understand the details of ocean heat uptake. Here we present a detailed, process-based analysis of ocean heat uptake (OHU) processes in HiGEM1.2, an atmosphere-ocean general circulation model with an eddy-permitting ocean component of 1/3° resolution. Similarly to various other models, HiGEM1.2 shows that the global heat budget is dominated by a downward advection of heat compensated by upward isopycnal diffusion. Only in the upper tropical ocean do we find the classical balance between downward diapycnal diffusion and upward advection of heat. The upward isopycnal diffusion of heat is located mostly in the Southern Ocean, which thus dominates the global heat budget. We compare the responses to a 4xCO2 forcing and an enhancement of the windstress forcing in the Southern Ocean. This highlights the importance of regional processes for the global ocean heat uptake. These are mainly surface fluxes and convection in the high latitudes, and advection in the Southern Ocean mid-latitudes. Changes in diffusion are less important. In line with the CMIP5 models, HiGEM1.2 shows a band of strong OHU in the mid-latitude Southern Ocean in the 4xCO2 run, which is mostly advective. By contrast, in the high-latitude Southern Ocean regions it is the suppression of convection that leads to OHU. In the enhanced windstress run, convection is strengthened at high Southern latitudes, leading to heat loss, while the magnitude of the OHU in the Southern mid-latitudes is very similar to the 4xCO2 results. Remarkably, there is only very small global OHU in the enhanced windstress run. The wind stress forcing just leads to a redistribution of heat. We relate the ocean changes at high Southern latitudes to the effect of climate change on the Antarctic Circumpolar Current (ACC). It weakens in the 4xCO2 run and strengthens in the wind stress run. The weakening is due to a narrowing of the ACC, caused by an expansion of the Weddell Gyre, and a flattening of the isopycnals, which are explained by a combination of the wind stress forcing and increased precipitation. Springer-Verlag Berlin Heidelberg, 2015 Ocean heat uptake nationallicence Process-based analysis nationallicence Advection-diffusion balance nationallicence Isopycnal diffusion nationallicence Eddy-permitting ocean model nationallicence Southern Ocean nationallicence Antarctic Circumpolar Current nationallicence Kuhlbrodt T. NCAS, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, RG6 6BB, Reading, UK aut Gregory J. NCAS, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, RG6 6BB, Reading, UK aut Shaffrey L. NCAS, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, RG6 6BB, Reading, UK aut Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3205-3226 0930-7575 45:11-12<3205 2015 45 382 https://doi.org/10.1007/s00382-015-2534-0 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-015-2534-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kuhlbrodt T. NCAS, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, RG6 6BB, Reading, UK aut NATIONALLICENCE 700 1- Gregory J. NCAS, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, RG6 6BB, Reading, UK aut NATIONALLICENCE 700 1- Shaffrey L. NCAS, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, RG6 6BB, Reading, UK aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3205-3226 0930-7575 45:11-12<3205 2015 45 382