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Development of the adjoint of GEOS-Chem

Henze, D. K. and Seinfeld, J. H. (2006) Development of the adjoint of GEOS-Chem. Atmospheric Chemistry and Physics Discussions, 6 (5). pp. 10591-10648. ISSN 1680-7367.

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We present the adjoint of the global chemical transport model GEOS-Chem, focusing on the chemical and thermodynamic relationships between sulfate – ammonium – nitrate aerosols and their gas-phase precursors. The adjoint model is constructed from a combination of manually and automatically derived discrete adjoint algorithms and numerical solutions to continuous adjoint equations. Explicit inclusion of the processes that govern secondary formation of inorganic aerosol is shown to afford efficient calculation of model sensitivities such as the dependence of sulfate and nitrate aerosol concentrations on emissions of SOx, NOx, and NH3. The adjoint model is extensively validated by comparing adjoint to finite difference sensitivities, which are shown to agree within acceptable tolerances; most sets of comparisons have a nearly 1:1 correlation and R2>0.9. We explore the robustness of these results, noting how insufficient observations or nonlinearities in the advection routine can degrade the adjoint model performance. The potential for inverse modeling using the adjoint of GEOS-Chem is assessed in a data assimilation framework through a series of tests using simulated observations, demonstrating the feasibility of exploiting gas- and aerosol-phase measurements for optimizing emission inventories of aerosol precursors.

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Seinfeld, J. H.0000-0003-1344-4068
Additional Information:© Author(s) 2006. This work is licensed under a Creative Commons License. Received: 4 October 2006 – Accepted: 14 October 2006 – Published: 19 October 2006 This work was supported by U.S. Environmental Protection Agency, grant R832158, and the National Science Foundation, grant NSF ITR AP&IM 0205198, which provided access to the TeraGrid resources at the National Center for Supercomputing Applications. We wish to thank M. Kopacz and A. Sandu for valuable insight and technical support.
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Environmental Protection Agency (EPA)R832158
Issue or Number:5
Record Number:CaltechAUTHORS:HENacpd06
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7043
Deposited By: Archive Administrator
Deposited On:06 Jan 2007
Last Modified:02 Oct 2019 23:38

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