The O2/N2 Ratio and CO2 Airborne Southern Ocean Study (ORCAS) Principal Investigators: Britton Stephens and Matthew Long (National Center for Atmospheric Research) Ralph Keeling (Scripps), Colm Sweeney (U. Colorado), Eric Kort (U. Michigan) Collaborative science team: Nikki Lovenduski, and David Munro (U. Colorado); Michelle Gierach (JPL); Heidi Dierssen (U. Connecticut); Hugh Ducklow (LDEO); Scott Doney (WHOI); Nicolas Cassar (Duke); Oscar Schofield (Rutgers); Andy Thompson (CalTech); Jorge Sarmiento (Princeton); Sue Schauffler and Eric Apel (NCAR/ACD); Elliot Atlas (U. Miami); Jorgen Jensen (NCAR/EOL) :: ORCAS :: 1 Southern Ocean air-sea fluxes: model uncertainty CMIP5 modeled air-to-sea CO2 fluxes Sink Source PgC/month Obs Anav et al. 2013 :: ORCAS :: 2 CO2 flux is a small residual of opposing terms; O2 flux is not Sea-to-air fluxes Obs. Obs. CMIP5 CO2 fluxes Anav et al. 2013 CO2 flux drivers :: ORCAS :: O2fluxes S. Mikaloff-Fletcher O2 flux drivers 3 NSF/NCAR HIAPER Gulfstream V High-performance Instrumented Airborne Platform for Environmental Research :: ORCAS :: 4 Hemispheric scale O2 plume Meridional section: O2 in Austral Summer courtesy of B. Stephens :: ORCAS :: 5 O2 /N2 Ratio and CO2 Airborne Southern Ocean Study (ORCAS) :: ORCAS :: 6 Research questions What are the magnitudes and interrelationships of summertime air-sea O2 and CO2 fluxes over the Southern Ocean at regional to zonal scales? What are the dominant processes driving the seasonal evolution and spatial variability in these fluxes? :: ORCAS :: 7 ORCAS Jan–Feb 2016? Core measurement objectives I Large-scale O2 and CO2 distributions: 50◦ S–70◦ S, 0–14km; I Vertical O2 :CO2 ratios across boundary-layer top and through mid-troposphere; I O2 and CO2 fluxes inferred from Lagrangian particle dispersion back-trajectories: (1) regional scale, using upwind/downwind flights 30-hr apart, (2) whole campaign. GV Scientific Payload Instrument Airborne Oxygen Instrument (AO2) Quantum Cascade Laser Spectrometer(QCLS) Picarro Medusa Flask Sampler Portable Remote Imaging Spectrometer (PRISM) Advanced Whole Air Sampler (AWAS) HIAPER Trace Organic Gas Analyzer (TOGA) :: ORCAS :: Measurement δ(O2 /N2 ), CO2 CO2 , CH4 , N2 O, CO CO2 , CH4 , H2 O δ(O2 /N2 ), CO2 , δ(Ar/N2 ), δ 13 C, δ 18 O, and ∆14 C of CO2 Hyperspectral water-leaving radiance Over 80 trace gases, including DMS, OCS, halocarbons, MeONO2 , isoprene Over 60 VOCs, including nitrate species, DMS, and VSL halocarbons Institution NCAR EOL Harvard/Aerodyne/NCAR NOAA/CU NCAR/Scripps JPL NCAR/U. Miami NCAR 8 Earth system models used for hypothesis testing 0 6 gazing incr. d−1] wind-stress incr. gazing reduced −5 Bioavail. Fe incr. −10 CO2 Flux 0 Source O A J J Sink −1 d ] −2 CO2 flux [mmol m 20 0 −20 J MM M A M O S 0 Source Source S A J O O S O S AS MA A J JJJJ J M M −4 N NN −60 −12 J A S O N D J F M A M J D grazing increased D ◦ M −40 D F F FF M MM A > 60 S −60 D J J J −8 −10 80−90W (S) Enhanced winter mixing AA control D D N M −6 −40 D N J N N grazing reduced Sink −2 D control Sink Sink J N J JJ O Source grazing increased F F F M A O A A MMM JJ J F < 60◦ S 2 40 :: ORCAS :: J SS AA 4 O2 Flux 60 J −2 −4 6 80 O flux [mmol m−2 d−1] 2 No Fe lim. O A 2 80−90W (N) Enhanced winter mixing S 4 CO2 flux [mmol m −2 PI-slope 2 CO flux [mmol m−2 d−1] 8 Vertical mix. param. change 5 A grazing reduced −20 0 20 40 O2 flux [mmol m−2 d−1] 60 9 Synergistic opportunities :: ORCAS :: I Palmer LTER cruise and ∆O2 /Ar sampling aboard the L.M. Gould I SOCCOM biogeochemical profiling floats I Gliders? I others? 10
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