Primary production and carbon export rates across the subpolar N. Atlantic Ocean basin based on triple oxygen isotope and dissolved O₂ and Ar gas measurements

[1] Gross photosynthetic O₂ production (GOP) rates in the subpolar North Atlantic Ocean were estimated using the measured isotopic composition of dissolved oxygen in the surface layer on samples collected on nine transits of a container ship between Great Britain and Canada during March 2007 to June 2008. The mean basin-wide GOP rate of 226 ± 48 mmol O₂ m⁻² d⁻¹ during summer was double the winter rate of 107 ± 41 mmol O₂ m⁻² d⁻¹. Converting these GOP rates to equivalent ¹⁴C-based PP (¹⁴C-PP_eqv) yielded rates of 1005 ± 216 and 476 ± 183 mg C m⁻² d⁻¹ in summer and winter, respectively, that generally agreed well with previous ¹⁴C-based PP estimates in the region. The ¹⁴C-PP_eqv estimates were 1–1.6× concurrent satellite-based PP estimates along the cruise track. A net community production rate (NCP) of 87 ± 12 mmol O₂ m⁻² d⁻¹ (62 ± 9 mmol C m⁻² d⁻¹) and NCP/GOP of 0.35 ± 0.06 in the mixed layer was estimated from O₂/Ar and ¹⁷Δ measurements (61°N 26°W) during spring bloom conditions in May 2008. Contrastingly, a much lower long-term annual mean NCP or organic carbon export rate of 2.8 ± 2.7 mol C m⁻² yr⁻¹ (8 ± 7 mmol C m⁻² d⁻¹) and NCP/GOP of 0.07 ± 0.06 at the winter mixed layer depth was estimated from 15 years of surface O₂ data in the subpolar N. Atlantic collected during the CARINA program.