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Hydrogen, H2, is a naturally occuring trace gas in the atmosphere. About half of the atmospheric H2 is produced by photochemical oxidation of methane and other hydrocarbons. The other half originates from fuel combustion and biomass burning. Of the estimated total emissions of 70 to 90 Tg/year, one-quarter is associated with human activities. The two main sinks for H2 are photochemical loss through reaction with the hydroxyl radical (OH), and a biological sink at the surface through consumption by soil microorganisms. A potential hydrogen economy would result in leakage of H2 and thus increasing levels of H2 in the atmosphere. |
 Annual surface concentrations of H2 and HD simulated with the GEOS-CHEM model. |
We are developing a global simulation of atmospheric hydrogen and its isotope, HD, with the GEOS-CHEM global model of tropospheric chemistry. On the left-hand side, we show the results of a preliminary simulation of both gases with our model. |
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We are in the process of validating our simulations through comparisons to surface observations of H2 from the CMDL network (see figure below) as well as through observations of HD obtained by Paul Quay and his group during ship cruises (figure on the right). The model captures the latitudinal gradient and seasonal cycle of H2. We also obtain a good simulation of the gradient in dD.
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 Observed and simulated latitudinal gradient in dD. |
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People:
Project Leader: Heather Price, postdoctoral
fellow (heather@atmos.washington.edu)
Our collaborators in this work are: Paul Quay, Andrew Rice and Richard Gammon at the University of Washington.
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Price, H.U., L. Jaeglé, P.D. Quay, A. Rice, and R. Gammon, "Molecular hydrogen in a global chemical transport model: Constraints from surface observations of H2 and HD", American Geophysical Union, San Francisco, December 2004.
Funding:
Program on Climate Change (UW), postdoctoral fellowship to Heather Price.