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Impact of Near‐Inertial Waves on Vertical Mixing and Air‐Sea CO 2 Fluxes in the Southern Ocean
Author(s) -
Song Hajoon,
Marshall John,
Campin JeanMichel,
McGillicuddy Dennis J.
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2018jc014928
Subject(s) - biogeochemical cycle , vertical mixing , outgassing , mixing (physics) , flux (metallurgy) , environmental science , atmospheric sciences , carbon cycle , oceanography , geology , climatology , ecosystem , physics , quantum mechanics , ecology , chemistry , materials science , astronomy , environmental chemistry , metallurgy , biology
We report the significant impact of near‐inertial waves (NIWs) on vertical mixing and air‐sea carbon dioxide (CO 2 ) fluxes in the Southern Ocean using a biogeochemical model coupled to an eddy‐rich ocean circulation model. The effects of high‐frequency processes are quantified by comparing the fully coupled solution (ONLINE) to two offline simulations based on 5‐day‐averaged output of the ONLINE simulation: one that uses vertical mixing archived from the ONLINE model (CTRL) and another in which vertical mixing is recomputed from the 5‐day average hydrodynamic fields (5dAVG). In this latter simulation, processes with temporal variabilities of a few days including NIWs are excluded in the biogeochemical simulation. Suppression of these processes reduces vertical shear and vertical mixing in the upper ocean, leading to decreased supply of carbon‐rich water from below, less CO 2 outgassing in austral winter, and more uptake in summer. The net change amounts up to one third of the seasonal variability in Southern Ocean CO 2 flux. Our results clearly demonstrate the importance of resolving high‐frequency processes such as NIWs to better estimate the carbon cycle in numerical model simulations.