Title: Observing mesoscale eddy effects on mode water subduction and transport in the North Pacific

Journal: Nature Communications, doi: 10.1038/ncomms10505

Authors: XU L. -X., P. -L. Li, S. -P Xie*, Q. -Y. Liu

Abstract:While modelling studies suggest that mesoscale eddies strengthen the subduction of modewaters, this eddy effect has never been observed in the field. Here we report results from afield campaign from March 2014 that captured the eddy effects on mode-water subductionsouth of the Kuroshio Extension east of Japan. The experiment deployed 17 Argo floats in ananticyclonic eddy (AC) with enhanced daily sampling. Analysis of over 3,000 hydrographicprofiles following the AC reveals that potential vorticity and apparent oxygen utilizationdistributions are asymmetric outside the AC core, with enhanced subduction near thesoutheastern rim of the AC. There, the southward eddy flow advects newly ventilated modewater from the north into the main thermocline. Our results show that subduction by eddylateral advection is comparable in magnitude to that by the mean flow—an effect that needsto be better represented in climate models.