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| Titel |
A Lagrangian model of air-mass photochemistry and mixing using a trajectory ensemble: the Cambridge Tropospheric Trajectory model of Chemistry And Transport (CiTTyCAT) version 4.2 |
| VerfasserIn |
T. A. M. Pugh, M. Cain, J. Methven, O. Wild, S. R. Arnold, E. Real, K. S. Law, K. M. Emmerson, S. M. Owen, J. A. Pyle, C. N. Hewitt, A. R. MacKenzie |
| 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 ; 5, no. 1 ; Nr. 5, no. 1 (2012-01-31), S.193-221 |
| Datensatznummer |
250002300
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| Publikation (Nr.) |
 copernicus.org/gmd-5-193-2012.pdf |
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| Zusammenfassung |
| A Lagrangian model of photochemistry and mixing is described (CiTTyCAT,
stemming from the Cambridge Tropospheric Trajectory model of Chemistry And
Transport), which is suitable for transport and chemistry studies throughout
the troposphere. Over the last five years, the model has been developed in
parallel at several different institutions and here those developments have
been incorporated into one "community" model and documented for the first
time. The key photochemical developments include a new scheme for biogenic
volatile organic compounds and updated emissions schemes. The key physical
development is to evolve composition following an ensemble of trajectories
within neighbouring air-masses, including a simple scheme for mixing between
them via an evolving "background profile", both within the boundary layer
and free troposphere. The model runs along trajectories pre-calculated using
winds and temperature from meteorological analyses. In addition, boundary
layer height and precipitation rates, output from the analysis model, are
interpolated to trajectory points and used as inputs to the mixing and wet
deposition schemes. The model is most suitable in regimes when the effects of
small-scale turbulent mixing are slow relative to advection by the resolved
winds so that coherent air-masses form with distinct composition and strong
gradients between them. Such air-masses can persist for many days while
stretching, folding and thinning. Lagrangian models offer a useful framework
for picking apart the processes of air-mass evolution over inter-continental
distances, without being hindered by the numerical diffusion inherent to
global Eulerian models. The model, including different box and trajectory
modes, is described and some output for each of the modes is presented for
evaluation. The model is available for download from a Subversion-controlled
repository by contacting the corresponding authors. |
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