SuppressedpCO₂in the Southern Ocean Due to the Interaction Between Current and Wind

Abstract

A negative wind stress curl to the south of the maximum westerly wind further creates upwelling through surface divergence (Carranza & Gille, 2015;Luis & Pandey, 2004), which allows the deep ocean to interact with the atmosphere (Marshall & Speer, 2012;Sallèe, 2018). Excessive precipitation and sea-ice melting over the Southern Ocean reduces the salinity of the upwelled water and shapes the characteristics of the Antarctic Intermediate Water. Newly upwelled water takes up heat from the atmosphere before subducting in the lower latitudes (

Discrepancies in temporal pCO2 variability from Earth System Models and pCO2-products related to high-latitude mixed layer dynamics and equatorial upwelling

“…The effect of ocean ventilation on carbon dynamics is an active research question (e.g., Talley et al, 2016;DeVries et al, 2017;Keppler and Landschützer, 2019;Morrison et al, 2022;Terhaar et al, 2022). Our őndings provide further evidence that intensiőed ocean mixing increases the upper ocean carbon content, thereby affecting F CO 2 , as shown primarily for the Southern Ocean in observations (Wu et al, 2019;Nicholson et al, 2022;Prend et al, 2022;Chen et al, 2022) and models (Kwak et al, 2021). In addition, shallow mixed layers generally co-occur with an increased stratiőcation in ESMs (Sallée et al, 2013), thereby inhibiting upward carbon and nutrient ŕuxes (Fu et al, 2016;Bourgeois et al, 2022;Fu et al, 2022).…”

“…The ocean circulation in particular was shown to substantially affect pCO 2 patterns (also termed circulation-driven pCO 2 changes; e.g., Gallego et al, 2018;Gruber et al, 2019;DeVries, 2022). For example, Southern Ocean observations and model results suggest that an intensiőed ocean mixing increases the upper ocean carbon content, thereby affecting F CO 2 (Wu et al, 2019;Kwak et al, 2021;Nicholson et al, 2022;Prend et al, 2022;Chen et al, 2022). Likewise, simulation results from Earth System Models (ESMs) indicate that a too strong stratiőcation suppresses carbon and nutrient ŕuxes or uptake (Fu et al, 2016;Bourgeois et al, 2022;Fu et al, 2022).…”

Inconsistency between ship- and Argo float-based pCO2 at the intense upwelling region of the Drake Passage, Southern Ocean

“…Although we did not extend our approach to the wider Southern Ocean due to the lack of ship-based data that prohibited the constructions of surface carbon balance calculation, we presume that the proposed theoretical framework for Drake Passage would also work for the Indo-Pacific sector which are hot spots for upwelling of natural CO 2 from Indo-Pacific Deep Water (Chen et al, 2022;Prend et al, 2022). It is reasonable that some discrepancies between ship-and float-derive pCO 2 could be attributed to episodic or short-term (weekly to monthly) variabilities during the float observation (e.g., storms and mesoscale events) which would cause peaks in pCO 2 (Kwak et al, 2021;Nicholson et al, 2022). However, our study reveals that the inconsistency existed throughout the observation on a longer timescale (yearly; Figure 6D).…”

Global Ocean pCO2 Variation Regimes: Spatial Patterns and the Emergence of a Hybrid Regime

“…Mesoscale‐induced advection and diapycnal mixing can also facilitate biological productivity by supplying heat and nutrients (Spingys et al., 2021; Uchida et al., 2020). Further, mesoscale air‐sea interactions with wind, known as the relative wind effect, can reduce momentum transfer (Seo et al., 2023) and affect the DIC contribution to p CO 2 by altering vertical mixing throughout the year, resulting in a more negative non‐thermal p CO 2 in the spring season in the Southern Ocean (Kwak et al., 2021), which likely corresponds to the DIC‐driven p CO 2 season as we observed in the hybrid regime. We note that biases in mixed‐layer depth in low‐resolution models can be largely reduced in eddy‐resolving models given that mesoscale eddies can control the spatial variability in mixed‐layer depth in winter (Treguier et al., 2023).…”