Working Group III : Future Research to evaluate Global Change impact in the region
On the basis of available evidence the following items should be considered:
- tropospheric ozone and other photo-oxidants: formation processes and trends in relation to emissions and meteorological circulations.
- seasonal variation of precursor emissions (AVOC's, BVOC's, NOx, oxygenated VOC's, impact of new fuels, ...).
- parametrization of biogenic emissions.
- role of anthropogenic, biogenic and crustal aerosols on the radiative properties of the troposphere.
- aerosol characterization (including Saharan dust): chemical composition, organic and inorganic fractions and physical properties.
- organic aerosols, chemical composition.
- aerosol formation and transport in relation to the atmospheric circulation and processes in this region (heterogeneous processes).
- aerosol deposition processes and fluxes.
- role of aerosols in cloud formation processes, radiation balance, scattering and absorption.
- deposition mechanisms, impacts on the ecosystems, and feedback processes linked to the atmospheric circulations of photooxidants and by-products.
- direct impacts of photo-oxidants on crops and natural vegetation, possible feedback via surface properties changes.
- Influence of fertilizer use (including atmospheric N deposition) and irrigation on N2O, and CH4 fluxes.
- possible perturbation of summer storm regimes in the mountains surrounding the basin due to direct heating of the lower troposphere via photochemical processes (to more than 3 km).
- possible perturbations via feedback processes producing aerosols, e.g., NO3 deposition on the sea, algae blooming, DMS production, oxidation to SO2 and sulfates, etc., and their role in cloud processes.
- Large scale budgets of clean and aged airmasses within the basin (specific pollutants and/or other species could be used as tracers of opportunity), input regions and venting mechanisms, their annual evolution and height dependence, contribution of airmasses aged in the Mediterranean to global processes (in the central Atlantic, Middle East, etc.).
- use of the EUPHORE (EUropean PHOtoREactor) outdoor test facility to assess and refine chemical mechanisms to be incorporated within models, and to document the effects of expected changes, e.g., fuel changes.

 To carry out this research it is foreseen that systematic monitoring programs and intensive field measurement campaigns should be undertaken, and that these must be supported by selected modeling exercises using the available experimental data. Further to this, meteorological models should be developed and/or tested to describe observed circulations and, once verified, to support the tuning of chemical models to reproduce the documented chemical cycles. Finally, to evaluate the linkages between the Mediterranean basin and the synoptic systems at the global scale, high resolution modeling should be undertaken, using the verified meteorological and chemical modules, with the Mediterranean basin in the center of the domain.

 Needs for monitoring Global Change in the region
It could be based on:
- a long term air monitoring network for relevant atmospheric species in specific test areas, including preferred venting paths (e.g. Tarifa), to assess trends (O3, NOx, some AVOC's, BVOC's, full radiative fluxes, radicals). It should consist of a few advanced stations, with state of the art maintenance and data validation procedures, located in specific sites.
- the collection and screening of available data to verify, or otherwise present, hypothesis and to guide the design of new experiments. A substantial amount of data may already exist in scattered form.

 Needs in training and capacity building
Intensive courses for permanent staff scientists from participating, or cooperating, institutions around the Mediterranean and other European countries. These people should be involved in the specific research programs designed to document identified processes and in the interpretation of the data. For Northern Africa, the training courses and/or pilot projects could be funded via EC's INCO type programs.