Response of the Pacific Sector of the Southern Ocean to Wind Stress Variability From 1995 to 2017

Drifter, satellite, expendable bathythermograph (XBT), and Argo float data are used to study the response of the Pacific Sector of the Southern Ocean (PSSO) to the wind stress field in the period 1995-2017, in terms of eddy field, water mass transport, and heat fluxes at large and regional scales. Increasing wind stress over the PSSO in those two decades led to a growth of the Eddy Kinetic Energy (EKE) in the region of the Antarctic Circumpolar Current (ACC). Increases of the EKE occur with delays of 1-4 years with respect to peaks in the zonal component of the wind stress. The persistent ACC meander located south of New Zealand (between 150 degrees E and 180 degrees W and 50 degrees S to 66 degrees S) responds to the interannual wind variations earlier than the entire ACC branch in the PSSO. In the same area, an estimate of the ACC transport based on in situ data shows interannual variability but no significant decadal trend over the study period. The effects of the EKE variability on the meridional eddy heat fluxes are significant on interannual scales. The strengthening of the EKE field leads to a local increase in the poleward meridional eddy heat fluxes in the PSSO, especially in the ACC band. The weakening of the EKE field defines an area of equatorward meridional eddy heat fluxes in the middle of the PSSO (south of 40 degrees S, between 130 degrees W and 160 degrees W) and prevalent poleward fluxes in the further western and eastern regions. Key Points In situ data describe the interannual and decadal variability of the Antarctic Circumpolar Current in the Southern Pacific Ocean The interannual variability of the eddy field and of the eddy heat fluxes is related to the zonal wind stress field The meridional eddy heat fluxes show a larger variability on interannual than on decadal scales