Improving global chemical simulations of the upper troposphere-lower stratosphere with sequential assimilation of MOZAIC data

The quantity and variety of atmospheric measurements of chemical constituents are strongly increasing. both for in situ and remote-sensing observing systems. This is an incentive to develop data assimilation schemes for atmospheric chemistry models. in the perspective of building realistic three-dimensional time-dependent distributions of observed and chemically related non-observed compounds. Sequential data assimilation experiments within the global Chemistry and Transport Model MOCAGE hake been conducted, in the Perspective of using the MOZAIC database and meteorological analyses to drive a global simulation of ozone and related tracers, focussing specially on the upper troposphere-lower stratospheres the chemistry and dynamics in this region of the atmosphere are of great environmental interest, yet they are currently very difficult to model. Assimilation of subsonic flight-level observations of ozone is anticipated to provide a significant contribution to improve numerical simulations, Results obtained with two different sequential data assimilation schemes are presented. The experiments have been Set LIP on an 8-d period in February 1997. The "non-local" data assimilation technique appears preferable to the "local" technique tested. since the benefits, of assimilation for the former appear to remain for longer, possibly LIP to 3-4 d in the model integration after the data assimilation phase.