1. Global simulation of H 2 and HD with GEOS-CHEM Heather Price 1, Lyatt Jaeglé 1, Paul Quay 2, Andrew Rice 2, and Richard Gammon 2 University of Washington, Seattle Departments of 1 Atmospheric Sciences and 2 Oceanography 2 nd GEOS-CHEM Users Meeting 6 Apr 2005

2. Sinks (Tg/yr) MOZART Novelli GEOS-CHEM OH c 1519 17 Soils c 5556 59 Total 7075 77 Sources (Tg/yr) MOZART a Novelli c GEOS-CHEM d Hauglustaine Fossil Fuel 16 15±10 20 Biomass Burning 13 16±5 10 Biofuel 5 b 4.4 Photochemical 31 40 41 Methane Oxidation 26 ± 9 27 BVOC Oxidation 14 ± 7 14 Ocean 5 3 ± 2 ~ N fixation 5 3 ± 1 ~ Total 70 77 76 a Hauglustaine et al., 2002; Photochemical production includes Methane(27.5Tg) and nonmethane hydrocarbons (14.2Tg): Isoprene, Acetone, Monoterpenes, and Methanol. b Andreae & Merlet, 2001: bf H 2 /CO = 0.32 per molecule c Novelli, 1999: bb H 2 /CO = 0.29, for fossil fuels Novelli uses global CO source of 500Tg/yr from Logan et al., 1981, Pacnya & Graedel, 1995 and WMO, 1995 Lifetime, years 1.92-3 2.1 Annual Global Budget of Molecular Hydrogen in the Troposphere

3. H 2 and HD in the GEOS-CHEM Model Based on the GEOS-CHEM offline CO simulation v5.05.04 Sinks OH d H 2 + OH → H 2 O + H k = 1.5x10 -13 e -2000/T SoilsUniform Deposition Velocity over land = 0.042 cm/s Sources H 2 /CO (per molecule) Fossil Fuels 0.59 a Biomass Burning 0.30 c Biofuels 0.32 b Photochemical yield relative to CO Methane Oxidation 0.50 BVOC Oxidation 0.50 a Oliver et al., 1996 CO emission inventory EDGAR H 2 /CO (per molecule) = 0.588 or 0.042Tg H 2 /CO b Andreae & Merlet, 2001: bf H 2 /CO = 0.32 or 0.023Tg H 2 /CO c Novelli, 1999; bb H 2 /CO= 0.30 or 0.022Tg H 2 /CO d JPL reported average of nine studies detailed in Ravishankara et al., 1981 and in excellent agreement with measurements by Talukdar et al., 1996. k

4. H 2 ppbv GEOS-CHEM Simulation of H 2 Surface (JJA) Surface (DJF)

5. Validating the GEOS-CHEM H 2 simulation against CMDL H 2 Observations CMDL sites Surface (JJA) CMDL sites H 2 ppbv Surface (DJF) (Novelli, 1999) Climate Monitoring and Diagnostics Laboratory: ftp://140.172.192.211/ccg/h2/flask/

6. Fall % Bias: -0.86 R: 0.71 Summer % Bias: 0.71 R: 0.80 Winter % Bias: 1.25 R: 0.67 Spring % Bias: 0.70 R: 0.56 Latitude H 2 ppbv H 2 Interhemispheric Gradient ~40 ppbv gradient GEOS-CHEM H 2 ppbv GEOS-CHEM H 2 simulation vs. CMDL observations GEOS-CHEM model NOAA CMDL observations (1989-2003) CMDL H 2 ppbv -90 -50 0 50 90 400 450 500 550 600 600 550 500 450 400 600 550 500 450 400 Spring Summer Autumn Winter Correlation (r=0.76) model-obs obs Bias: x100 = 0.45%

7. H 2 Seasonal Cycle Barrow (89-03) Bermuda(91-03) Mauna Loa(89-03) 40.7 S, 144.7 E Model CMDL observations Ascension (89-03) Cape Grim(91-03) Palmer Station(94-03) Northern Hemisphere Southern Hemisphere H 2 ppbv Month 2 4 6 8 10 12 Month 2 4 6 8 10 12 7.9 S, 14.4 W Month 2 4 6 8 10 12 Month 2 4 6 8 10 12 Month 2 4 6 8 10 12 Month 2 4 6 8 10 12 H 2 ppbv 650 600 550 500 450 400 650 600 550 500 450 400 71.3 N,156.6 W 32.4 N, 64.7 W19.5 N, 155.6 W 64.9 S, 64.0 W

8. H 2 Vertical Profiles Nov 2002-Aug 2004 Park Falls, Wisc. 45.93N,-90.27W H 2 (ppbv) 400 500 600 420420 km Poker Flat, Alaska 65.07N, -147.29W 400 500 600 H 2 (ppbv) Sept Oct Nov March April May Cook Islands -21.25S, –159.83W 400 500 600 H 2 (ppbv) km 420420 Soil Model Observations

9. Adding hydrogen isotope (HD) to the GEOS-CHEM model 1.Model development based on measured ratios of HD/H 2 for various sources, sinks, and reservoirs 2.Will give additional constraint to the H 2 budget sources and sinks 3.Determine the contributions of sources and sinks to atmospheric  D and interhemispheric gradient (Gerst & Quay, 2000, 2001)

10. Deuterium Source & Sink Signatures Soil, fossil fuel, and biomass burning fractionation: Gerst & Quay, 2001 OH fractionation: Ehhalt et al., 1989 δD of the global Troposphere = 130 % o TermH 2 Tg/yr  D% o  Fossil Fuels 20-196 Biomass Burning10-293 Biofuels4.4-293 Methane Oxidation28156 BVOC Oxidation14156 OH Sink170.601 Soil Sink600.943

11. JJA  D (% 0 ) SMOW H 2 ppbv Annual  D Surface H 2 and  D

12.  D (% 0 vs SMOW) 1998,2002,2004 Ocean Cruise Observations Barrow Cheeka Peak DJF  D Model, Surface & Cruise Observations Biofuels & Fossil Fuels

13.  D vs. Latitude  sinks  D (atmos) ~40 % 0 gradient  D Observational Data from Rice & Quay, 2004 and Gerst, & Quay, 2001. Additional enrichment from Stratosphere?

14. GEOS-CHEM captures well the H 2 and  D latitudinal gradient (H 2 ~40ppbv,  D~40% o ) and seasonality. Soil Sink uncertainty: incorporate soil moisture, precipitation, to better constrain soil deposition Next, help explain the  D observations of stratospheric enrichment (Röckmann et al., 2003; Rahn et al., 2003) Could  D measurements be used to constrain Asian biofuel emissions? Summary Biofuel + Fossil Fuel Biomass Burning Fossil Fuels DJF  D