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Lagrangian Modelling of Transport Processes in the Atmosphere

Lagrangian Modelling of Transport Processes in the Atmosphere

Recent satellite observations and dynamical studies have demonstrated the existence of filamentary structures in chemical tracer fields in the stratosphere. It is also evident that such features are often below the spatial resolution of the highest-resolution Eulerian models that have been used up to the present time.
These observations have motivated the development of chemical Lagrangian transport of tracers, in particular the Chemical Lagrangian Model of the Stratosphere (CLaMS) in Jülich.
With a Lagrangian approach, one considers an ensemble of air parcels following the fluid and, consequently, forming a time-dependent irregular grid moving with the fluid elements; by contrast, with an Eulerian approach, one considers a fixed spatial grid through which fluid elements move. An advantage of the Lagrangian approach is the ability to resolve small-scale features, often observed in stratospheric flows as elongated filaments.
The images shows the temperature distributions as obtained from the coupled model system EMAC/CLaMS. The moving dots represent air parcels following the atmospheric flow in the upper troposphere and lower stratosphere (17 to 17 km altitude). The color code illustrates the atmospheric temperature from 180 K (blue) to 230 K (red).

Data: Charlotte Hoppe, IEK-7 and Lars Hoffmann, Forschungszentrum Jülich, JSC
Visualization:Sonja Habbinga and Herwig Zilken, Forschungszentrum Jülich, JSC