Direct and Indirect Measurements of DMS, Ozone, and CO Fluxes Over the Eastern Pacific Ocean:

1. Direct and Indirect Measurements of DMS, Ozone, and CO Fluxes Over the Eastern Pacific Ocean: The connection between dynamical and chemical lifetimes in the marine boundary layer ACD Seminar25 August, 2003 Ian Faloona (erstwhile NCAR/ASP)University of California @ Davisw/ Don Lenschow, Bjorn Stevens, Teresa Campos, Sam Hall, Byron Blomquist, Don Thornton, and Alan Bandy (photo courtesy of G. Vali, UWyo)

2. GOES-10 Image from Sunrise RF05 DYCOMS-II Prevailing Wind Flight Area

3. MBL Vertical Structure DYCOMS-II Stevens et al., BAMS, 84 (2003)

4. DYCOMS-II Flights DYCOMS-II Stevens et al., BAMS, 84 (2003)

5. Target Area SSTs DYCOMS-II Stevens et al., BAMS, 84 (2003)

6. Fast O3 Chemiluminescence Schematic DYCOMS-II O3 + NO  NO2 NO2  NO2 + hPint ~ 10 Torr ScrollPumps Det. Limit: ~0.25 ppb (1sec) Accuracy: ~ 2 ppbFreq. Response: ~8 Hz Sample Flow~ 12 SLPM MassFlowControl red filter Dry Ice chilledPMT housing NO cylinder Air Flow Pcontrol

7. RAF CO DYCOMS-II

8. CO VUV Resonance Fluorescence DYCOMS-II

9. Dimethylsulfide (DMS) DYCOMS-II • Important component of Earth’s sulfur cycle, ~25 Tg/yr [Watts, Atm. Env., 2000] released from the oceans by phytoplankton (like the coccolithophore to the left). • Its metabolic precursor dimethyl sulfonium propionate (DMSP) is believed to be used in osmotic regulation. • Only a small fraction of oceanic DMS is released to the atmosphere. • The principal component of the ‘smell of the sea’, and is thought to be widely supersaturated in seawater. • Oxidation end products H2SO4 & MSA serve as important CCN components (chem ~ 2 days).

10. Drexel APIMS DYCOMS-II • Alan Bandy’s group at Drexel Univ. has developed a fast enough (nominally 25 Hz) measurement to make the first direct eddy correlation determination of DMS fluxes from the ocean. [Bandy et al., JGR, 2002] • Atmospheric Pressure Ionization Mass Spectrometry (APIMS) technique is a ‘soft’ chemical ionization technique using protonated water clusters mass spec. • Proton transfer reaction to create detected ion DMSH+: • Average sensitivity of ~80 counts per second/pptv • Lower limit of detection of 0.1 pptv (one second integration)

11. Feigning Consciousness at 4:00 a.m. DYCOMS-II

12. Ozone Profiles RF07 DYCOMS-II vdep = .03 cm/s

13. DMS Profiles RF03 DYCOMS-II

14. Scalar Budget Equations DYCOMS-II assuming horizontal homogeneity in the scalar fields: Flux Divergence Net Photochemical Production/Loss

15. Ignoring Entrainment DYCOMS-II Numerous modeling studies have invoked ‘missing oxidants’ to explain the diurnal behavior of DMS in the remote MBL [Suhre et al., JGR, 1995; Yvon et al., JGR, 1996; Chin et al., JGR, 1996; Sciare et al., JGR, 2000; Andreae et al., Chemosphere, 2003] as a consequence of ignoring, or underestimating, entrainment fluxes.

16. Entrainment Velocities DYCOMS-II Faloona et al., submitted JAS (2003)

17. Comparison of Timescales DYCOMS-II

18. RF04 Back Trajectory (NE corner) DYCOMS-II

19. Mean CO Profiles DYCOMS-II

20. RF07 HYSPLIT Back Trajectory DYCOMS-II

21. Oceanic CO DYCOMS-II Production: hn+ CDOM  CO(aq) Losses: microbial degradation & sea-air fluxes • World’s oceans are ubiquitously supersaturated with CO [Bates et al., JGR, 1995], daily average supersaturation ratios range 1.4 – 85. • ~85% of oceanic CO is cycled internally, not released to the atmosphere [Zafiriou et al., Global Biogeochem. Cycles, 2003]; taq ~ 0.2 - 2 days. • Fluxes from oceans represents only ~2% of global CO source strength, but it may influence MBL oxidation by modulating OH.

22. Estimate Oceanic CO Fluxes DYCOMS-II If one assumes that, on average, the entrainment fluxes are balanced by the surface fluxes to sustain the jump across the MBL inversion, which in the absence of oceanic emissions would decay within 1-2 days, then:

23. Surface Fluxes DYCOMS-II † ‡ † Watts, Atmos. Env., 2000, global average (Sciare et al., JGR, 2000, show peaks from Atlantic Transect of >20).‡ Bates et al., JGR, 1995, all over the Pacific.

24. Scalar Budget Equations DYCOMS-II assuming horizontal homogeneity in the scalar fields: Flux Divergence Net Photochemical Production/Loss at night the in-situ Prod/Loss terms are zero except for aqueous reaction of O3 and DMS [Lee & Zhou, JGR99, 3597-3605, 1994], kaq(T,LWC)

25. O3 Budget DYCOMS-II

26. DMS Budget DYCOMS-II

27. Horizontal Variability & d/dt DYCOMS-II

28. DMS Gradients DYCOMS-II

29. SeaWiFS July 2001 DYCOMS-II

30. QuickSCAT Ocean Winds RF03 DYCOMS-II

31. Concluding Summary DYCOMS-II • Fast DMS measurements have enabled very accurate estimates of MBL entrainment. • Entrainment fluxes should not be underestimated in their importance in controlling MBL concentrations and diurnal variability. • Marine chemical fluxes of CO, DMS, and probably O3 exhibit pronounced horizontal inhomogeneity. • Despite the paucity of measurements, by the standards of traditional airborne atmospheric chemistry experiments, DYCOMS-II has provided valuable insight by fast measurements, focused, Lagrangian flight plans, and nocturnal flights.

32. Conclusions [cont’d] DYCOMS-II • Inferred CO fluxes from the vicinity of the California current are about an order of magnitude larger than anything previously estimated. • The “indirect aerosol” effect seems to be alive and kicking in the coastal stratocumulus. • Littoral air mass modification may result in a shutdown of drizzle and thus reduce scavenging of sulfate and other soluble compounds that are eventually advected onshore. • DMS sources seem to be consistently stronger away from coastal upwelling, indicating a phase offset in primary ocean productivity and DMS emissions to the atmosphere.