Winter Air-Sea CO2 Fluxes Constructed From Summer Observations of the Polar Southern Ocean Suggest Weak Outgassing

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Mackay, N, Watson, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley / American Geophysical Union 2021
• Subjects: Southern Ocean
• Online Access: http://hdl.handle.net/10871/126891; https://doi.org/10.1029/2020JC016600

This is the final version. Available on open access from Wiley via the DOI in this record Data Availability Statement: All of the data products used in this study are freely available online, links can be found through the following cited sources: Bakker et al. (2016), Olsen et al. (2019), Roemmich and Gilson (2009), Meier et al. (2017), Bushinsky, Gray, et al. (2017), Dlugokencky et al. (2017), Holte et al. (2017), Atlas et al. (2011), Kalnay et al. (1996), Rödenbeck, Keeling, et al. (2013), Bushinsky, Landschützer, et al. (2019), and Landschützer, Gruber, and Bakker (2017). CCMP Version-2.0 vector wind analyses are produced by Remote Sensing Systems; these data are available at www.remss.com. Argo data were collected and made freely available by the International Argo Program and the national programs that contribute to it (http://www.argo.ucsd.edu, http://argo.jcommops.org). The Argo Program is part of the Global Ocean Observing System (Argo 2000). Argo float data and metadata are from the Global Data Assembly Center (Argo GDAC, http://doi.org/10.17882/42182). The Southern Ocean plays an important role in the global oceanic uptake of CO2. Estimates of the air-sea CO2 flux are made using the partial pressure of CO2 at the sea surface ((Formula presented.)), but winter observations of the region historically have been sparse, with almost no coverage in the Pacific or Indian ocean sectors south of the Polar front in the period 2004–2017. Here, we use summertime observations of relevant properties in this region to identify subsurface waters that were last in contact with the atmosphere in the preceding winter, and then reconstruct “pseudo observations” of the wintertime (Formula presented.). These greatly improve wintertime coverage south of the Polar Front in all sectors, improving the robustness of flux estimates there. We add the pseudo observations to other available observations of (Formula presented.) and use a multiple linear regression to produce a gap-filled time-evolving estimate of (Formula ...