Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/os-2017-42
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Jun 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Ocean Science (OS).
Submesoscale CO2 variability across an upwelling front off Peru
Eike E. Köhn1, Sören Thomsen1, Damian L. Arévalo-Martínez1, and Torsten Kanzow2 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
2Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Abstract. While being a major source for atmospheric CO2 the Peruvian upwelling region exhibits strong variability in surface fCO2 on short spatial and temporal scales. Understanding the physical processes driving the strong variability is of fundamental importance for constraining the effect of marine emissions from upwelling regions on the global CO2 budget. In this study, a frontal decay on length scales of 𝒪(10 km) was observed off the Peruvian coast following a pronounced decrease in downfrontal wind speed with a time lag of 9 hours. Simultaneously, the sea-to-air flux of CO2 on the inshore (cold) side of the front dropped from up to 80 to 10 mmol m-2 day-1, while the offshore (warm) side of the front was constantly outgassing at a rate of 10–20 mmol m-2 day-1. Based on repeated ship transects the decay of the front was observed to occur in two phases. The first phase was characterized by a development of coherent surface temperature anomalies which gained in amplitude over 6–9 hours. The second phase was characterized by a disappearance of the surface temperature front within 6 hours. Submesoscale mixed layer instabilities were present but seem too slow to completely remove the temperature gradient in this short time period. Dynamics such as a pressure driven gravity current appear to be a likely mechanism behind the evolution of the front.

Citation: Köhn, E. E., Thomsen, S., Arévalo-Martínez, D. L., and Kanzow, T.: Submesoscale CO2 variability across an upwelling front off Peru, Ocean Sci. Discuss., https://doi.org/10.5194/os-2017-42, in review, 2017.
Eike E. Köhn et al.
Eike E. Köhn et al.
Eike E. Köhn et al.

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