Title:
Global sources and distribution of atmospheric methyl chloride

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dc.contributor.advisor Wang, Yuhang
dc.contributor.author Yoshida, Yasuko en_US
dc.contributor.committeeMember Armistead Russell
dc.contributor.committeeMember Athanasios Nenes
dc.contributor.committeeMember David Tan
dc.contributor.committeeMember Dickinson, Robert E.
dc.contributor.department Earth and Atmospheric Sciences en_US
dc.date.accessioned 2006-09-01T19:30:52Z
dc.date.available 2006-09-01T19:30:52Z
dc.date.issued 2006-07-03 en_US
dc.description.abstract Global simulations of atmospheric methyl chloride (CH3Cl) are conducted using the GEOS-Chem model in order to understand better its sources and sinks. Though CH3Cl is one of the most abundant organic chlorine species in the stratosphere, not much is known about its sources and the budget remains unbalanced. In addition to the known sources (1.5 Tg yr-1) from ocean, biomass burning, incineration/industry, salt marshes, and wetlands, a hypothetical aseasonal biogenic source of 2.9 Tg yr-1 is added in order to match needed emissions. Observations from 7 surface sites and 8 aircraft field experiments are used to evaluate the model simulations. The model results with a priori emissions and sinks reproduce CH3Cl observations at northern mid and high latitudes reasonably well. However, the seasonal variation of CH3Cl at southern mid and high latitudes is severely overestimated. Simulated vertical profiles show disagreements in the vicinities of major sources, principally reflecting the uncertainties in the estimated distributions of our added pseudo-biogenic and the biomass burning sources. Inverse modeling is applied to obtain optimal source distributions of CH3Cl on the basis of surface and aircraft observations and model results. We resolve the seasonal dependence of the biogenic and biomass burning sources for each hemisphere. The aircraft in situ measurements are found to provide better constraints on the emission sources than surface measurements. The a posteriori emissions result in better agreement with the observations particularly at southern high latitudes. The a posteriori biogenic and biomass burning source decrease by 13 and 11% to 2500 and 545 Gg yr-1, respectively, while the a posteriori net ocean source increases by about a factor of 2 to 761 Gg yr-1. The decrease in biomass burning emissions is largely due to the reduction in the emissions in seasons other than spring in the northern hemisphere. The inversion results indicate that the biogenic source has a clear winter minimum in both hemispheres, likely reflecting the decrease of biogenic activity during that season. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 3907329 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/11537
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Global modeling en_US
dc.subject Sources and sinks
dc.subject Bayesian
dc.subject Inverse modeling
dc.subject.lcsh Methyl chloride en_US
dc.subject.lcsh Sinks (Atmospheric chemistry) en_US
dc.subject.lcsh Atmospheric chemistry Observations en_US
dc.subject.lcsh Atmospheric chlorine compounds Mathematical models en_US
dc.title Global sources and distribution of atmospheric methyl chloride en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Wang, Yuhang
local.contributor.corporatename School of Earth and Atmospheric Sciences
local.contributor.corporatename College of Sciences
relation.isAdvisorOfPublication 978cb158-0230-4051-b51e-c904074e42bc
relation.isOrgUnitOfPublication b3e45057-a6e8-4c24-aaaa-fb00c911603e
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
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