WP 5.3: Analysis of long-term trends:
Consistency between GEOmon data and model
results
Objectives
- Long-term integration of chemical transport models in both the troposphere and the stratosphere on the global
scale and at the European scale.
We analyse existing model runs which have been created either in former EU projects or in other published studies. Future work will include the creation of new, improved long-term model simulations. The period of interest is 1980-2000 for the stratosphere and 1960-2000 for the troposphere.
Long-term model simulations will be performed and analysed in three areas:
- For the stratosphere, the SLIMCAT state-of-the-art global three-dimensional (3-D) chemical transport model (CTM) with detailed gas-phase and heterogeneous chemistry and aerosol schemes has been integrated over the last few decades. These runs will be used to assess the overall model performance and to characterise any intrinsic trends in the model (e.g. due to the analyses). Then, the models will be integrated with the constraints of assimilation of GEOmon data using the operators developed in WP 4.2, to produce an optimised combination of model and observations for later trend analysis.
- For the global troposphere, relevant long-term simulations have already been performed within the
RETRO (EU-FP5) project. The period 1960-2000 was simulated with three state-of-the-art CTMs
(MOZECH, TM4, LMDz-INCA) including varying meteorology, surface emissions of ozone
precursors, and ozone influx from the stratosphere. Output from these simulations will be analysed and distributed within the framework of GEOmon and, in due course, will be complemented by additional simulations.
- For the European troposphere the CHIMERE chemistry-transport model will be used in its parallelized version. The main goal of the study is to estimate trends for the most important gaseous tropospheric species such as ozone, CO, NO2 over Europe.
The results will consist of trends averaged over the global model grids for direct comparisons (with associated
standard deviation), time series for several species and analysis of regular/extreme pollution events (with separation between seasons etc.), maps of tendencies to investigate regional weather regimes and large source areas such as
the influence of megacities.
A detailed description of the long-term simulations is available on the GEOmon intranet (for partners only, sorry).
