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Titel |
Development of a variational flux inversion system (INVICAT v1.0) using the TOMCAT chemical transport model |
VerfasserIn |
C. Wilson, M. P. Chipperfield, M. Gloor, F. Chevallier |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 7, no. 5 ; Nr. 7, no. 5 (2014-10-24), S.2485-2500 |
Datensatznummer |
250115744
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Publikation (Nr.) |
copernicus.org/gmd-7-2485-2014.pdf |
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Zusammenfassung |
We present a new variational inverse transport model, named INVICAT
(v1.0), which is based on the global chemical transport model
TOMCAT, and a new corresponding adjoint transport model,
ATOMCAT. The adjoint model is constructed through manually derived
discrete adjoint algorithms, and includes subroutines governing
advection, convection and boundary layer mixing, all of which are linear in the TOMCAT model. We present
extensive testing of the adjoint and inverse models, and also
thoroughly assess the accuracy of the TOMCAT forward model's
representation of atmospheric transport through comparison with
observations of the atmospheric trace gas SF6. The forward model
is shown to perform well in comparison with these observations,
capturing the latitudinal gradient and seasonal cycle of SF6 to
within acceptable tolerances. The adjoint model is shown, through
numerical identity tests and novel transport reciprocity tests, to
be extremely accurate in comparison with the forward model, with no
error shown at the level of accuracy possible with our machines. The
potential for the variational system as a tool for inverse modelling
is investigated through an idealised test using simulated
observations, and the system demonstrates an ability to retrieve
known fluxes from a perturbed state accurately. Using basic off-line
chemistry schemes, the inverse model is ready and available to
perform inversions of trace gases with relatively simple chemical
interactions, including CH4, CO2 and CO. |
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