High resolution Australian Subantarctic Net Community productivity estimates by in situ continuous dissolved O2/Ar measurements
Nicolas
Cassar, Princeton University, ncassar@princeton.edu
(Presenting)
Michael
L.
Bender, Princeton University, bender@princeton.edu
Peter
J.
DiFiore, Princeton University, pdifiore@princeton.edu
Bruce
A.
Barnett, Princeton University, bbarnett@princeton.edu
Bronte
Tilbrook, CSIRO, Australia, bronte.tilbrook@csiro.au
The concentration of oxygen (O2) in the surface ocean’s mixed layer reflects both biological and physical processes. Biological O2 supersaturation can be estimated by simultaneous measurements of the inert gas argon (Ar). We report continuous shipboard measurements of O2/Ar derived net community productivity (NCP) and export production by equilibrator inlet mass spectrometry (EIMS) in the Australian sector of the Subantarctic zone. Based on these continuous measurements, we estimate NCP during the austral summer 2007 in the Subantarctic zone to be around 70 mmol O2 m-2 d-1. Gross primary productivity (estimated from the oxygen triple isotope anomaly) and NCP both show significant spatial variability, with larger productivities near the Subtropical front, and a general trend of northward increase in productivity. These measurements are presented with respect to other measurements that were performed during the cruise including productivity (e.g. depth integrated pigments, oxygen and 14C incubations), and iron concentration and deposition measurements.
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