A Lagrangian View of Transport: CLaMS - Chemical Lagrangian Model of the Atmosphere

Abstract:
Both in situ and satellite observations of small-scale structures
have motivated the development of a novel chemistry transport model
(CLaMS) that is based on a Lagrangian formulation of the tracer
transport in the isentropic coordinates. Unlike Eulerian CTMs, CLaMS
considers an ensemble of air parcels on a time-dependent irregular grid.
The isentropic and cross-isentoropic advection in CLaMS occurs along the
trajectories which are driven by meteorological winds and eating/cooling
rates derived from a radiation calculation, respectively.
Recently. the model was extended through hybrid coordinate to surface,
incorporating the entire troposphere.

The irreversible part of transport, i.e.~mixing, is controlled by the
intensity of the deformations in the flow measured in terms of the
Lyapunov exponent and is correlated with the local horizontal strain and
vertical shear rates. Thus, CLaMS generalizes the idea of the (bulk)
effective diffusivity to a more realistic inhomogeneous (i.e.~driven by
spatial and time dependent flow deformations) and anisotropic
i.e.~dependent on the wind direction) mixing. High resolution
simulations of the chemical composition in the polar stratosphere and in
the UT/LS region within the tropical tropopause layer (TTL) will be
presented.
These examples demonstrate the model's ability to reproduce observed
small-scale structures as filaments or vortex remnants formed after the
vortex breakup and, consequently, its ability to simulate the
permeability of transport barriers such as the vortex edge, subtropical
jet or the tropopause.

Datum

30.01.2008

Uhrzeit

13:30 Uhr

Ort

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

ReferentIn

Paul Konopka, FZ Juelich

Chair


Zur Übersicht