Objectif
The present project will focus on three main areas of research: improvement of the model (physics, resolution, chemical and transport schemes), model intercomparison and long term simulations.
Task A. 3D model improvement
i) Chemistry
This sub-project includes:
- extending the gas phase scheme to introduce all the NOy, Cly, HOx, .. species contributing to the lower stratospheric ozone budget,
- developing and implementing schemes for the formation of PSCs (all types), the associated heterogeneous chemistry and their coupling with the model dynamics.
ii) Dynamics and transport
This sub-project includes:
- refining further some key parameterizations that contribute to the maintenance of meridional circulation (cf gravity wave drag parameterizations, radiation),
- assessing the stability of the overall model performances on the horizontal and vertical resolutions.
Task B. Model Intercomparison
To understand and evaluate the strength and possible weaknesses in the different model approaches a detailed model inter-comparison must be performed. This inter-comparison should not be restricted to the model dynamcis but should also include the minor species distributions. The chosen periods will match the intensive observing periods of the EASOE campaign, especially during January 1992 during which a subset of the UARS data will be eventually available.
Significant efforts will be devoted to the problem of model initialization of dynamical and chemical variables and their subsequent evolution during periods of about two weeks to one month.
Task C. Long term simulations
There is a significant variability in the NH thermal structure of the winter stratosphere. Some years show the development of a cold and stable polar vortex, whereas other are characterized by a succession of minor and major warmings resulting in elevated lower stratospheric temperatures. This atmospheric variability has a direct impact on the frequency of appearance of the PSC and the amount of air chemically perturbed.
Thus, the 3D models should be able to reproduce not only the mean state of the atmosphere but also its large scale variability. The various models (GCM and mechanistic) will be integrated over severall seasonal cycles with a varying degree of representation of the chemistry and different resolutions.
The model outputs will be compared to the atmospheric statistics and a valuable evaluation of the models usefulness for studies of the long term evolution of ozone depletion will be obtained.
Champ scientifique
Thème(s)
Data not availableAppel à propositions
Data not availableRégime de financement
CSC - Cost-sharing contractsCoordinateur
31057 TOULOUSE
France