Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 19, 2006 | Published
Journal Article Open

Development of the adjoint of GEOS-Chem


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.

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.

Attached Files

Published - HENacpd06.pdf


Files (3.7 MB)
Name Size Download all
3.7 MB Preview Download

Additional details

August 22, 2023
October 16, 2023