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Factors contributing to variability in p CO 2 and omega in the coastal Gulf of Maine.

Factors contributing to variability in p CO 2 and omega in the coastal Gulf of Maine. J. Salisbury, D. Vandemark, C. Hunt, C. Sabine, S. Musielewicz and others. Terms for discussion: p CO 2 and Ω. p CO 2 – partial pressure of carbon dioxide (μatm) = CO 2 concentration / solubility ( k)

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Factors contributing to variability in p CO 2 and omega in the coastal Gulf of Maine.

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  1. Factors contributing to variability in pCO2 and omega in the coastal Gulf of Maine. J. Salisbury, D. Vandemark, C. Hunt, C. Sabine, S. Musielewicz and others

  2. Terms for discussion: pCO2 and Ω pCO2 – partial pressure of carbon dioxide (μatm) = CO2 concentration / solubility (k) Omega (W) – Saturation index of the mineral aragonite Ω= [Ca2+][CO32-] Ksp

  3. In terms of Ocean Acidification, the Gulf of Maine is an interesting place. Big salinity range Freshwater endmember qualities Big temperature range Very productive

  4. Two freshwater sources: both poorly buffered DFO, Canada

  5. Big seasonal temperature range > 15° C /year DFO, Canada

  6. During the mixing season During the growing season CO2 Low CO2 High CO2 High CO2 High CO2 Coastal GOM highly productive and….. both the surface and deep waters interact with the atmosphere over short time scales (~annual). ? From Bozac et al., 2006 (North Sea Example)

  7. UNH time series stations in the Gulf of Maine Data shown is primarily from the CO2 buoy, with supporting pCO2 and bottle data from cruise stations (red)

  8. Decadal variability: Do we observe OA from increased atm CO2? Preliminary analyses on raw data xCO2 Ωaragonite

  9. Decadal variability from > atm CO2 ….. maybe! Mauna Loa was +2.2 ppm y-1 during this time xCO2 +/- 0.34 Note that omega and xCO2 are both positive! SST +0.2°C y-1 Omega_ar +/- 0.001

  10. Daily-to-seasonal variability in pCO2

  11. Analysis of daily-seasonal pCO2 variability in the context of a time resolving 1-d model Account for daily change in pCO2 within the mixed layer caused by the processes below: (units, change in pCO2 d-1) δpCO2Observed = δpCO2SOL + δpCO2AS + δpCO2H + δpCO2V + δpCO2NCP* Change attributable to air sea flux of CO2 out/in of mixed layer: f(wind, delta CO2, MLD) Change induced by changes in solubility, f(temp, salinity) Net change from horizontal mixing: f(pCO2 gradient *time) Net change from vertical mixing: f(ΔMLD, diffusion) Biology: the residual of (observed – sum of modeled terms) Similar to 1d models used by Shadwick et al, 2011 and Gruber et al, 1999

  12. Model results: Air-sea flux > 4 matm d-1 changes in solubility > 3 matm d-1

  13. Model results: Vertical processes > 4matm d-1 horizontal processes > 5matm d-1 Net biological processes> 5matm d-1

  14. High frequency changes: often > 20 matm d-1 individual components >10matm d-1 All components subject to future change - hydrology - net warming - mixing - wind variability

  15. Finally, use daily averaged dpCO2 output to explore the components of seasonal variability

  16. A seasonal cycle of controls on pCO2

  17. Conclusions: Changes in solubility, a-s flux, mixing, NCP, freshwater flux all significant sources of pCO2 and omega variability!! Results indicate a system that works on an annual frequency, but changes at daily – monthly time step. Unresolved issues: Have not yet characterized the natural variability of the carbonate system in the Gulf of Maine!!! Short term events important (storms, floods, NCP) Effect of circulation and freshwater sourcing. Apparent NCP in early summer?

  18. Thanks:

  19. Arctic - COLORS Coastal Land Ocean Interactions Arctic-COLORS is a Field Campaign Scoping Study funded by NASA's Ocean Biology and Biogeochemistry Program that aims to improve understanding and prediction of land-ocean interactions in a rapidly changing Arctic coastal zone, and assess vulnerability, response, feedbacks and resilience of coastal ecosystems, communities and natural resources to current and future pressures. Deliverable: a comprehensive report to NASA outlining the major scientific questions, and developing the initial study design and implementation concept for this new campaign  Focus on coastal ocean processes  A needed linkage between field campaigns focusing on the Arctic open ocean environment (e.g. ICESCAPE), and field activities focusing on Arctic river processes, chemistry and fluxes (e.g. ABoVE) Overarching objective: better understand the impact of climate change on land-ocean interactions in the Arctic Ocean, and examine the effect of these changes on river-dominated coastal ocean biology, biogeochemistry, biodiversity. Arctic

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