1. Airborne Observations of Atmospheric O 2 and CO 2 on Regional to Global Scales Britton Stephens (NCAR, Boulder, USA and NIWA, Wellington, New Zealand) Coauthors: Steve Shertz and Andrew Watt (NCAR), Jonathan Bent and Ralph Keeling (SIO), Steve Wofsy, Bruce Daube, Rodrigo Jimenez and Eric Kort (Harvard), Sara Mikaloff-Fletcher (NIWA)

2. Can be measured with: 1.Interferometer 2.Mass-spectrometer 3.Paramagnetic analyzer 4.Fuel-cell analyzer 5.Gas chromatograph 6.VUV absorption analyzer Atmospheric O 2 Measurements Provide insight into: 1.Global land-ocean carbon flux partitioning 2.Oceanic transport and exchange of O 2 and CO 2 3.Seasonal ocean productivity 4.Air-sea gas-exchange 5.Plant physiology 6.Fossil-fuel emission signals 7.Atmospheric transport  O 2 /N 2 (per meg) = [(O 2 /N 2 ) sample /(O 2 /N 2 ) reference -1]x 10 6

3. NCAR Airborne Oxygen Instrument (AO2) Vacuum ultraviolet absorption technique Xe lamp (147 nm) and CsI detector Adapted from shipboard design (Stephens et al., 2003) Active pressure and flow control to 10 -6 Switches every 2.5 seconds between sample and WT gas 5-second 1-sigma precision of ± 2 per meg Factor of 2-5 motion degradation is correctable O 2 sensor Flow control:

4. NCAR Airborne Oxygen Instrument (AO2) System components:

5. NCAR Airborne Oxygen Instrument (AO2) 8-hour flight 3-min cal

6. Stratosphere-Troposphere Analyses of Regional Transport START-08 PIs: Laura Pan (NCAR), Elliot Atlas (U. Miami), Ken Bowman (TAMU) NSF / NCAR Gulfstream V April – June, 2008 Physical and chemical studies of the UTLS region 20 flights for a total of 111 hours

7. June 23, 2008 at 1600 LT Descent into Grand Forks, ND Boundary-layer transition

8. HIPPO PIs: Harvard, NCAR, Scripps, NOAA Global and seasonal survey of CO 2, O 2, CH 4, CO, N 2 O, H 2, SF 6, COS, CFCs, HCFCs, O 3, H 2 O, black carbon, and hydrocarbons NSF / NCAR Gulfstream V 5 campaigns over 4 years HIPPO1 in January of 2009, with 13 flights for 85 hours Continuous profiling from surface to 10 km and to 15 km twice per flight HIAPER Pole-to-Pole Observations of Atmospheric Tracers HIPPO Flight tracks January 2009

9. January 12, 2009 HIPPO Profile at 80 N

10. January 20, 2009 HIPPO Profile at 65 S Southern Ocean O 2 outgassing

11. Comparison to HIPPO flask samples Possibly related to temperature gradients in reference cylinders Temperatures were measured at 6 points in the cylinder box Options exist for back-correcting and revising procedures to minimize effect

12. O 2 Cross Section, January, 2009 per meg

13. CO 2 Cross Section, January, 2009 AO2 Instrument ppm

14. APO Cross Section, January, 2009 Atmospheric Potential Oxygen: APO = O 2 + 1.1*CO 2 per meg

15. Preliminary model comparisons Fluxes: Mean ocean O 2 : Gruber et al., 2001 Seasonal ocean O 2 and N 2 : Garcia and Keeling, 2001 Mean ocean N 2 : Gloor et al., 2001 Seasonal + mean ocean CO 2 : Takahashi et al., 2009 Fossil-fuel CO 2 and O 2 : CDIAC January Mean APO from Climatological fluxes in TM3 HIPPO1 APO Observations per meg

16. Looking ahead: Laboratory experiments to isolate source of in situ – flask offset Software improvements to reduce remaining motion sensitivity 4 more HIPPO campaigns: Oct/Nov 2009, Apr 2010, Jun 2011, Sep 2011 We welcome collaboration with atmospheric, oceanic, and terrestrial modelers