[A-CG30] Extratropical oceans and atmosphere

[ACG30-P19] Cyclonic and Anticyclonic Contributions to Air-Sea Interactions around Midlatitude Oceanic Frontal Zones

*Satoru Okajima¹, Hisashi Nakamura¹, Thomas Spengler² (1.Research Center for Advanced Science and Technology, The University of Tokyo, 2.University of Bergen)

Keywords:Oceanic frontal zone, transient eddy, storm track, Air-sea interaction

The Kuroshio-Oyashio Extension and Gulf Stream frontal zones are crucially important for air-sea interactions that contribute to the formation of midlatitude storm-tracks and eddy-driven westerly jets. Recent studies indicate a critical role of synoptic-scale atmospheric disturbances for these air-sea interactions. However, specific roles of cyclonic and anticyclonic disturbances in the interactions have neither been quantified nor fully understood. In this study, we quantify cyclonic and anticyclonic contributions to climatological-mean transient eddy feedback forcing onto westerly jets, surface turbulent heat fluxes, and precipitation based on a methodology using local curvature of winds. Additionally, we evaluate the impact of the oceanic frontal zones on these contributions. The anticyclonic contribution plays an important role in shaping turbulent heat fluxes along oceanic fronts and transient eddy feedback forcing onto the upper-level westerly jets, while cyclonic vortices predominantly contribute to a precipitation response. The distinctive roles of cyclonic and anticyclonic contributions in the air-sea interactions around the oceanic frontal zones are instrumental in our deeper understanding of midlatitude air-sea interactions.