Our
understanding of biogeochemical and physical processes in the Southern Ocean,
which are critically important to future anthropogenic CO2 uptake
and global climate, is limited by the sparse spatial and temporal coverage of
existing oceanographic and atmospheric measurements. We will present
high-precision horizontal atmospheric O2 and CO2 concentration
gradients over the Southern Ocean from three independent observing networks. These
measurements reveal that, relative to southern mid-latitudes and Antarctica, CO2 concentrations over the
Southern Ocean are high during winter and low during summer (Fig. 1). This
suggests a seasonal variation between net CO2 summertime uptake and wintertime
release that is in disagreement with the T99 [Takahashi et al., 2002] dissolved pCO2 climatology,
which predicts year‑round CO2 uptake, and with the OCMIP‑2 biological
ocean general circulation models [BOGCMs, Doney
et al., 2004], which either predict year-round CO2 uptake or
opposite seasonality with wintertime uptake and summertime release.
Author: B.B. Stephens, D.F. Baker, M. Battle, R.F. Keeling, et al (stephens at ucar dot edu)
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