HR: 14:25h
AN: A23E-04    [Abstracts]
TI: Molecular hydrogen in a global chemical transport model: Constraints from surface and oceanic cruise observations of H$_{2}$
AU: * Price, H U
EM: hprice@u.washington.edu
AF: Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195-1640 United States
AU: Jaegle, L
EM: jaegle@atmos.washington.edu
AF: Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195-1640 United States
AU: Quay, P D
EM: pdquay@u.washington.edu
AF: School of Oceanography, University of Washinton, Seattle, WA 98195 United States
AU: Rice, A L
EM: drewrice@u.washington.edu
AF: School of Oceanography, University of Washinton, Seattle, WA 98195 United States
AU: Rice, A L
EM: drewrice@u.washington.edu
AF: Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, WA 98195 United States
AU: Gammon, R H
EM: gammon@u.washington.edu
AF: School of Oceanography, University of Washinton, Seattle, WA 98195 United States
AB: We present a new simulation of molecular hydrogen using the GEOS-CHEM global model of tropospheric chemistry in order to improve our understanding of the global budget of molecular hydrogen. Primary sources of H$_{2}$ (fossil fuel, biofuel, and biomass burning) used in the model are based on the GEOS-CHEM CO emission inventory scaled with the appropriate emission factors. Secondary sources from photochemical production arise from the photolysis of formaldehyde (resulting from oxidation of methane and volatile organic compounds, VOCs) and account for an estimated 45$%$ of the H$_{2}$ source. There is considerable uncertainty in the source of H$_{2}$ from formaldehyde, because of poor understanding of VOC sources and their yield to form formaldehyde. The main tropospheric sink, accounting for $\sim$80$%$ of the total, is uptake by enzymes in soils with the remainder through oxidation by hydroxyl (OH). There is also major uncertainty in the H$_{2}$ soil sink. In this presentation we will use surface observations of the seasonal cycle, as well as latitudinal and longitudinal gradients of H$_{2}$ from the global CMDL network and oceanic cruises to constrain the budget of H$_{2}$ in the atmosphere. We may also present preliminary simulations of the deuterium component of H$_{2}$ to further constrain the H$_{2}$ budget through differences in the isotopic signatures of sources and sinks.
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting