Assessment of the Carbonate Chemistry Seasonal Cycles in the Southern Ocean From Persistent Observational Platforms

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Williams, N. L., Juranek, L. W., Feely, R. A., Russell, Joellen, Johnson, K. S., Hales, B.
• Other Authors: Univ Arizona, Dept Geosci
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER GEOPHYSICAL UNION 2018
• Subjects: climatology; autonomous floats; Southern Ocean; ocean carbon cycle; climate change; pH; Pacific; Sea ice
• Online Access: http://hdl.handle.net/10150/631151; https://doi.org/10.1029/2017JC012917

Observations from Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemical profiling Argo floats are used to characterize the climatological seasonal cycles and drivers of dissolved inorganic carbon, total alkalinity, pH, the partial pressure of carbon dioxide (CO2), and the saturation state of aragonite at the surface and at 200 m across five Southern Ocean frontal regimes, including under sea ice. The Southern Ocean ranges from a temperature-dominated system in the northernmost Subtropical Zone to a biologically dominated system in the most poleward Seasonal Sea Ice Zone. In all zones, the ingassing or outgassing of CO2 must be balanced by geostrophic and Ekman transport, mixing from below, and particle transport of carbon into or out of the euphotic zone. The climatological seasonal cycles spanning the period from 2014 to 2017 compare favorably with existing climatologies in spring and summer and less so during winter months, at higher latitudes, and in ice-covered regions due, in part, to limited wintertime observations before SOCCOM. We observe increases in the carbon and nutrient content of surface waters south of the Subantarctic Front between climatological data products and the SOCCOM float climatologies, even after adjusting for anthropogenic change, suggesting a large-scale increase in the amount of upwelled carbon- and nutrient-rich deep waters. This increased upwelling corresponds to a positive Southern Annular Mode Index over 2014-2017 and likely acts to decrease the magnitude of the Southern Ocean sink of total carbon by increasing outgassing of natural CO2, especially during winter months. U.S. National Science Foundation's Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project under the NSF [PLR-1425989]; NASA [NNX14AP49G]; U.S. Argo through NOAA/JISAO [NA17RJ1232]; Pacific Marine Environmental Laboratory of NOAA; Ocean Observations and Monitoring Division, Climate Program Office, National Oceanic and Atmospheric Administration, United States; ARCS Foundation Oregon Chapter 6 month embargo; published online: 31 May 2018 This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [e-mail].