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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - 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
AU - Pugh, Thomas
AU - Cain, Michelle
AU - Methven, J.
AU - Wild, O.
AU - Arnold, S. R.
AU - Real, E.
AU - Law, K. S.
AU - Emmerson, K. M.
AU - Owen, S. M.
AU - Pyle, J. A.
AU - Hewitt, C. N.
AU - Mackenzie, Rob
N1 - © Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
PY - 2012/1/31
Y1 - 2012/1/31
N2 - 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.
AB - 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.
KW - TROPICAL RAIN-FOREST
KW - VOLATILE ORGANIC-COMPOUNDS
KW - HENRYS LAW CONSTANTS
KW - GROUND-LEVEL OZONE
KW - ISOPRENE OXIDATION MECHANISMS
KW - ABSORPTION CROSS-SECTIONS
KW - HYDROXY ALKYL NITRATES
KW - BIOGENIC NOX EMISSIONS
KW - LONG-RANGE TRANSPORT
KW - ATMOSPHERIC CHEMISTRY
U2 - 10.5194/gmd-5-193-2012
DO - 10.5194/gmd-5-193-2012
M3 - Journal article
VL - 5
SP - 193
EP - 221
JO - Geoscientific Model Development
JF - Geoscientific Model Development
SN - 1991-9603
IS - 1
ER -