Strong southern ocean carbon uptake evident in airborne observations
Long, Matthew C. ; Stephens, Britton B. ; McKain, Kathryn ; Sweeney, Colm ; Keeling, Ralph F. ; Kort, Eric A. ; Morgan, Eric J. ; Bent, Jonathan D. ; Chandra, Naveen ; Chevallier, Frederic ; Commane, Róisín ; Daube, Bruce C. ; Krummel, Paul B. ; Loh, Zoë ; Luijkx, Ingrid T. ; Munro, David ; Patra, Prabir ; Peters, Wouter ; Ramonet, Michel ; Rödenbeck, Christian ; Stavert, Ann ; Tans, Pieter ; Wofsy, Steven C.
Année de publication
<p align="justify">The Southern Ocean plays an important role in determining atmospheric carbon dioxide (CO2), yet estimates of air-sea CO2 flux for the region diverge widely. In this study, we constrained Southern Ocean air-sea CO2 exchange by relating fluxes to horizontal and vertical CO2 gradients in atmospheric transport models and applying atmospheric observations of these gradients to estimate fluxes. Aircraft-based measurements of the vertical atmospheric CO2 gradient provide robust flux constraints. We found an annual mean flux of -0.53 ± 0.23 petagrams of carbon per year (net uptake) south of 45°S during the period 2009-2018. This is consistent with the mean of atmospheric inversion estimates and surface-ocean partial pressure of CO2 (Pco2)-based products, but our data indicate stronger annual mean uptake than suggested by recent interpretations of profiling float observations.</p>