Global simulation of H2 and HD with GEOS-CHEM

Heather Price1, Lyatt Jaeglé1, Paul Quay2, Andrew Rice2, and Richard Gammon2

University of Washington, Seattle Departments of 1Atmospheric Sciences and 2Oceanography

2nd GEOS-CHEM Users Meeting 6 Apr 2005

Sinks (Tg/yr) MOZART Novelli GEOS-CHEMOHc 15 19 17Soilsc 55 56 59Total 70 75 77

Sources (Tg/yr) MOZARTa Novellic GEOS-CHEMd

HauglustaineFossil Fuel 16 15±10 20Biomass Burning 13 16±5 10Biofuel 5b 4.4Photochemical 31 40 41 Methane Oxidation 26 ± 9 27 BVOC Oxidation 14 ± 7 14Ocean 5 3 ± 2 ~N fixation 5 3 ± 1 ~Total 70 77 76

aHauglustaine et al., 2002; Photochemical production includes Methane(27.5Tg) and nonmethane hydrocarbons (14.2Tg): Isoprene, Acetone, Monoterpenes, and Methanol.bAndreae & Merlet, 2001: bf H2/CO = 0.32 per moleculecNovelli, 1999: bb H2/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 1.9 2-3 2.1

Annual Global Budget of Molecular Hydrogen in the Troposphere

H2 and HD in the GEOS-CHEM ModelBased on the GEOS-CHEM offline CO simulationv5.05.04

Sinks OHd H2 + OH → H2O + H k = 1.5x10 -13 e-2000/T

Soils Uniform Deposition Velocity over land = 0.042 cm/s

Sources H2/CO (per molecule)Fossil Fuels 0.59a

Biomass Burning 0.30c

Biofuels 0.32b

Photochemical yield relative to CO Methane Oxidation 0.50 BVOC Oxidation 0.50

aOliver et al., 1996 CO emission inventory EDGAR H2/CO (per molecule) = 0.588 or 0.042Tg H2/CObAndreae & Merlet, 2001: bf H2/CO = 0.32 or 0.023Tg H2/CO cNovelli, 1999; bb H2/CO= 0.30 or 0.022Tg H2/COd JPL reported average of nine studies detailed in Ravishankara et al., 1981 and in excellent agreement with measurements by Talukdar et al., 1996.

k

H2 ppbv

GEOS-CHEM Simulation of H2

Surface (JJA) Surface (DJF)

Validating the GEOS-CHEM H2 simulation against CMDL H2 Observations

CMDL sites

Surface (JJA)

CMDL sites

H2 ppbv

Surface (DJF)

(Novelli, 1999)Climate Monitoring and Diagnostics Laboratory: ftp://140.172.192.211/ccg/h2/flask/

Fall % Bias: -0.86R: 0.71 Summer % Bias: 0.71R: 0.80

Winter % Bias: 1.25R: 0.67 Spring % Bias: 0.70R: 0.56

Latitude

H2 p

pb

vH2 Interhemispheric Gradient

~40 ppbv gradient

GE

OS

-CH

EM

H2

pp

bv

GEOS-CHEM H2 simulation vs. CMDL observations

GEOS-CHEM modelNOAA CMDL observations (1989-2003)

CMDL H2 ppbv

-90 -50 0 50 90

400 450 500 550 600

600

550

500

450

400

600

550

500

450

400SpringSummerAutumnWinter

Correlation (r=0.76) model-obs obs

Bias: x100 = 0.45%

H2 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)

NorthernHemisphere

SouthernHemisphere

H2 p

pbv

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

H2 p

pbv

650

600

550

500

450

400

650

600

550

500

450

400

71.3 N,156.6 W 32.4 N, 64.7 W 19.5 N, 155.6 W

64.9 S, 64.0 W

H2 Vertical Profiles Nov 2002-Aug 2004

Park Falls, Wisc. 45.93N,-90.27W

H2 (ppbv)

400 500 600

4

2

0

km

Poker Flat, Alaska65.07N, -147.29W

400 500 600H2 (ppbv)

SeptOctNov

MarchAprilMay

Cook Islands-21.25S, –159.83W

400 500 600H2 (ppbv)

km

4

2

0

km

Soil

ModelObservations

Adding hydrogen isotope (HD) to the GEOS-CHEM model

1. Model development based on measured ratios of HD/H2 for various sources, sinks, and reservoirs

2. Will give additional constraint to the H2 budget sources and sinks

3. Determine the contributions of sources and sinks to atmospheric D and interhemispheric gradient (Gerst &

Quay, 2000, 2001)

Deuterium Source & Sink Signatures

Mass Balance & Equations of Interest

dM*Ratmos/dt = Sources - Sinks

[ (Soil * [(Datmos /1000)+1] *

soil) + (OH * [(dDatmos /1000)+1] * OH) ]

D=[(HD/HH)x/(HD/HH)SMOW -1] *1000

DSources /1000)+1]= [(Datmosphere /1000)+1] *

sinks

Soil, fossil fuel, and biomass burning fractionation: Gerst & Quay, 2001OH fractionation: Ehhalt et al., 1989

δD of the global Troposphere = 130 %o

Term H2 Tg/yr D%o

Fossil Fuels 20 -196Biomass Burning 10 -293Biofuels 4.4 -293Methane Oxidation 28 156BVOC Oxidation 14 156OH Sink 17 0.601Soil Sink 60 0.943

JJA

D (%0)SMOWH2 ppbv

AnnualD

Surface H2 and D

D (%0 vs SMOW)

1998,2002,2004Ocean CruiseObservations

Barrow

Cheeka Peak

DJF D Model, Surface & Cruise Observations

Biofuels& Fossil Fuels

D vs. Latitude

s

inks

D

(atm

os)

~40 %0

gradient

D Observational Data from Rice & Quay, 2004 and Gerst, & Quay, 2001.

Additional enrichment from Stratosphere?

• GEOS-CHEM captures well the H2 and D latitudinal gradient (H2~40ppbv, 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 FuelBiomass

Burning

FossilFuels

DJF D