Publication: Towards a fully Lagrangian atmospheric modelling system

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Title Towards a fully Lagrangian atmospheric modelling system
Authors/Editors* J.M. Alam, J.C. Lin
Where published* Monthly Weather Review
How published* Journal
Year* 2008
Volume In Review
Publisher American Meteorological Society
Improvement of currently available Lagrangian atmospheric models is necessary for accurate simulation of transport and chemistry in the atmosphere. Such models are not fully Lagrangian – they do not solve both the dynamical and tracer equations simultaneously in the Lagrangian frame. A fully Lagrangian numerical model is, therefore, presented for calculating atmospheric flows. The model employs a Lagrangian mesh of particles to approximate the nonlinear advection processes for all dependent variables simultaneously. Verification results for simulating sea-breeze circulations in a dry atmosphere are presented. Comparison with Defant’s analytical solution for the sea-breeze system enabled quantitative assessment of the model’s convergence and stability. An average of 20 particles in each cell of an 11× 20 staggered grid system are required to predict the two dimensional sea-breeze circulation, which accounts for a total of about 4400 particles in the Lagrangian mesh. Comparison with Eulerian and semi-Lagrangian models shows that the proposed fully-Lagrangian model is more accurate for the sea-breeze circulation problem. Further, the Lagrangian model is about 20 times faster than the semi-Lagrangian model and about 2 times faster than the Eulerian model. These results point toward the value of constructing an atmospheric model based on the fully Lagrangian approach.
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