[A-CG32] Extratropical oceans and atmosphere

[ACG32-07] An influence of oceanic mesoscale eddies on the air-sea heat exchange in the North Pacific Ocean revealed by the high-resolution ocean reanalysis

★Invited Papers

*Yuma Miyaji¹, Shoichiro Kido², Hiroyuki Tomita¹, Youichi Tanimoto^1,2 (1.Hokkaido University, Graduate school of Environmental Science/Faculty of Environmental Earth Science, 2.JAMSTEC)

Keywords:Oceanic mesoscale eddy, Air-sea interaction, Sea surface heat flux, Air-sea heat exchange

Thanks to advance in satellite observations and high-resolution ocean/climate modeling, the importance of ocean mesoscale eddies (OMEs) has been increasingly recognized in recent decades. However, more comprehensive and quantitative description of the role played by OMEs in modulating the air-sea heat exchange is warranted to establish a complete picture of extratropical air-sea interaction. In the present study, we investigated the influence of OMEs on the air-sea heat exchange by analyzing an eddy-resolving ocean reanalysis data (JCOPE-FGO), with a specific focus on the North Pacific. Mesoscale eddies in the North Pacific during 1993-2021 were first detected using an Eulerian method based on curvature vorticity at each grid point, instead of the conventional Lagrangian methods (Fig. 1a). The extracted grid points with the anticyclonic (cyclonic) rotation showed positive (negative) sea surface temperature anomalies from the climatologies with more than 85% accuracy. Composite temperature anomalies of the detected warm and cold mesoscale eddies adequately represent horizontal and vertical characteristics (Lens-shaped thermal anomalies extending from the core of OMEs between the sea surface and the sub-surface ocean; Fig. 1b, c). Further comparison of related field with and without OMEs revealed that the downward (upward) anomalies of the heat exchange over cold (warm) eddies contributed to 20% increases (decreases) of the annual mean ocean heat uptake in the central North Pacific.