Overestimated Eddy Kinetic Energy in the Eddy‐Rich Regions Simulated by Eddy‐Resolving Global Ocean–Sea Ice Models

• Published in: Geophysical research letters 2022-06, Vol.49 (11), p.n/a
• Main Authors: Ding, Mengrong, Liu, Hailong, Lin, Pengfei, Hu, Aixue, Meng, Yao, Li, Yiwen, Liu, Kexiu
• Format: Article
• Language: English
• Subjects: Atmospheric circulation; Atmospheric models; Coherence; Eddies; Eddy kinetic energy; eddy-resolving ocean general circulation model; eddy-rich regions; Energy; ENVIRONMENTAL SCIENCES; General circulation models; geology; Growth stage; Gulf Stream; Ice models; Kinetic energy; Mesoscale eddies; mesoscale eddy properties; Mesoscale phenomena; Modelling; Ocean circulation; Oceanic general circulation model; Oceans; OMIP-2; Properties; Regions; Satellite observation; Sea ice; Sea ice models; Simulation; Vortices
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL098370

The performance of eddy‐resolving global ocean–sea ice models in simulating mesoscale eddies is evaluated using six eddy‐resolving experiments forced by different atmospheric reanalysis products. Interestingly, eddy‐resolving ocean general circulation models (OGCMs) tend to simulate more (less) energetic eddy‐rich (eddy‐poor) regions with a smaller (larger) spatial extent than satellite observation, which finally shows that larger (smaller) mesoscale energy intensity (EI) is simulated in the eddy‐rich (eddy‐poor) regions. Quantitatively, there is an approximately 27%–60% overestimation of EI in the eddy‐rich regions, which are mainly located in the Kuroshio–Oyashio Extension, the Gulf Stream, and the Antarctic Circumpolar Currents regions, although the global mean EI is underestimated by 25%–45%. Apparently, the eddy kinetic energy in the eddy‐poor region is underestimated. Further analyses based on coherent mesoscale eddy properties show that the overestimation in the eddy‐rich regions is mainly attributed to mesoscale eddies’ intensity and is more prominent when mesoscale eddies are in their growth stage. Plain Language Summary Realistic simulation of mesoscale eddies is crucial in correctly reproducing observed large‐scale circulation. However, the state‐of‐the‐art eddy‐resolving ocean general circulation models (OGCMs) simulate a less energetic surface ocean on the global scale. Previous studies show that the biases in simulating global mesoscale eddies by eddy‐resolving OGCMs are not uniformly distributed. Therefore, we investigate the performances of eddy‐resolving OGCMs in simulating mesoscale eddies in two kinds of regions, eddy‐rich and eddy‐poor. Our results show that the eddy‐resolving OGCMs tend to simulate more (less) energetic eddy‐rich (eddy‐poor) regions with a smaller (larger) spatial extent with the metric eddy kinetic energy intensity. To further understand the simulated biases in the eddy‐rich and eddy‐poor regions, we analyze coherent mesoscale eddy properties after eddies are identified and tracked. We find that the overestimation in the eddy‐rich regions is mainly contributed by coherent mesoscale eddies’ intensity rather than frequency and is more prominent when mesoscale eddies are in their growth stage. Our results give an in‐depth understanding of how well eddy‐resolving OGCMs can perform in simulating the observed mesoscale eddies on the regional scale. Key Points Surface mesoscale energy intensity in the eddy‐rich regions is si