John Marshall

Cecil and Ida Green Professor of Oceanography, MIT

Anomalous chlorofluorocarbon uptake by mesoscale eddies in the Drake Passage region

Anomalous chlorofluorocarbon uptake by mesoscale eddies in the Drake Passage region.

(Song, H., Marshall, J., Gaube, P., and McGuillicudy, D), Journal of Geophysical Research, vol. 120, no. 2, pp. pages, 2015.

Abstract

The role of mesoscale eddies in the uptake of anthropogenic chlorofluorocarbon-11 (CFC-11) gas is investigated with a 1/20° eddy-resolving numerical ocean model of a region of the Southern Ocean. With a relatively fast air-sea equilibrium time scale (about a month), the air-sea CFC-11 flux quickly responds to the changes in the mixed layer CFC-11 partial pressure (pCFC-11). At the mesoscale, significant correlations are observed between pCFC-11 anomaly, anomalies in sea surface temperature (SST), net heat flux, and mixed layer depth. An eddy-centric analysis of the simulated CFC-11 field suggests that anticyclonic warm-core eddies generate negative pCFC-11 anomalies and cyclonic cold-core eddies generate positive anomalies of pCFC-11. Surface pCFC-11 is modulated by mixed layer dynamics in addition to CFC-11 air-sea fluxes. A negative cross correlation between mixed layer depth and surface pCFC-11 anomalies is linked to higher CFC-11 uptake in anticyclones and lower CFC-11 uptake in cyclones, especially in winter. An almost exact asymmetry in the air-sea CFC-11 flux between cyclones and anticyclones is found.

doi = 10.1002/2014JC010292