WORLD METEOROLOGICAL ORGANIZATION

UNITED NATIONS ENVIRONMENT PROGRAMME

FRANCE

France is active in most areas of stratospheric ozone research, as well as in the study of the impact of the change of the stratospheric composition on the climate and the UV-B radiation at the surface. The stratospheric ozone research is now part of a recently defined programme called National Programme on Atmospheric Chemistry, or PNCA, which includes both stratospheric and tropospheric studies. This new programme was triggered by the awareness that the tropopause is in fact an artificial barrier and that the regions situated on either sides, the upper troposphere and the lower stratosphere should be studied as a whole to understand the overall ozone issue. This programme is jointly funded by CNRS, CNES, Ministry of Defence and Ministry of Environment and coordinated by CNRS.

The scientific components of this programme are:
- Stratosphere-Troposphere and Chemistry-Dynamical coupling
- Tropospheric ozone and precursors
- Aerosols and heterogeneous chemistry
- Interactions with Climate
- Biosphere-Atmosphere Interactions.

A component of the precedent programme carried out since 1991, with the support of the Ministry of Transport, the Aircraft Ozone Programme, has focused its objectives more specifically on issues relevant of the impact of aviation both subsonic and supersonic on the stratosphere and environment. Its results and plans will be taken into account in what follows. In the future it is likely to be run in cooperation with the PNCA.
One fact which dominates the field of stratospheric research is the close cooperation which has been developed between the European teams through the European Commission 2nd, 3rd and 4th Framework programmes, and which has led to the two major Arctic campaigns EASOE and SESAME. As these have been co-funded by the national budgets, they may be mentioned in several of the presentations.
The French laboratories are also participating in the different activities of the SPARC Programme, the component of WCRP dealing with the impact of stratospheric change on Climate, and France welcomes the international SPARC Office at CNRS in Verrières-le-Buisson.

Current and planned activities in France are as follows:

Monitoring

France is assuming a large responsibility in the NDSC (Network for Detection of Stratospheric Changes), which is the ground-based part of the long-term monitoring of ozone and parameters relevant of the ozone issue (T°, CIO, NOx, UV-B). France has a major role in 3 main stations: The Alpine station with its components of Observatoire de Haute Provence and Bure, The Dumont d'Urville Station, in Antarctica, and the one recently set-up at La Réunion. Furthermore France is an active participant in the ALOMAR Lidar station, in Andoya, Norway, which has applied to become a secondary station of NDSC. Due to its geographic situation and its advanced lidar instrumentation, this station has an important role to play in the study of the conditions of formation of PSCs.
In addition to this contribution to NDSC, a large network of SAOZ visible Spectrometers, developed and built in France, has been implemented in the recent years, it now counts 18 stations, 7 of them being under the responsibility of CNRS. The SAOZ instruments used from the ground can monitor total ozone, NO2, OClO and BrO, and regular balloons flights of the same instruments provide the vertical distribution of the same constituents. Table 1 gives the sites of this newly implemented network.

Campaigns

The European SESAME campaign (Second European Stratospheric Arctic and Mid-latitude Experiment) has involved all the French teams both experimenters and modelers. Ground-based, balloon and aircraft instruments were used extensively in coordination with the other European countries, mostly to better understand the role of the polar vortex as a ''leaking barrier" between the polar and mid-latitude ozone. The ZEBRE campaign initiated by the French Aircraft Ozone Programme took place in the spring of 1995 and was aimed toward the study of the formation of Polar Stratospheric Clouds (PSCs) in the contrail of Concorde. The analysis of the data of both campaigns is still in progress. In relationship with the impact of aircraft and within the European Programme the French teams participated actively in the AERONOX, MOZAIC and POLINAT projects. It should be mentioned that the MOSAIC project run by a CNRS laboratory in Toulouse is the first project using commercial aircraft to monitor ozone both in the troposphere and at the altitude of flight which is half of the time in the troposphere and half in the stratosphere, and that its success is now in the process to be followed by several countries.
A wide scale balloon campaign, called STRATEOLE, is still being planned for the late 90s to study the Antarctic polar vortex with both dynamical and chemistry measurements to understand the mechanisms contributing to the "dilution " of the ozone hole at mid-latitude.

Space Programme

After the important role played in the validation of UARS instruments in the 1991-1994 period, the analysis of UARS data is still going on in most laboratories using the data base DUCAT developed by CNES. One should mention also the French participation in several space programmes as POAM-2 on SPOT-3, GOME on ERS-2 ILAS on ADEOS, and the preparation of the ENVISAT-1 mission to be launched in 1998. In particular significant efforts are dedicated to the development of algorithms and software for processing and interpreting the high resolution vertical profiles of ozone, aerosols, water vapour, NO2, temperature to be obtained from the French proposed GOMOS spectrometer to be launched aboard ENVISAT.
In the framework of the PNCA, the interest is also focusing on measurements of tropospheric composition as in the realisation of IASI, an Advanced Infrared Sounder developed as a joint FrenchItalian to be on board the METOP mission, scheduled for the beginning of the next century.

Laboratory measurements

In addition to the on-going programme of molecular spectroscopy and kinetics to support the interpretation of stratospheric constituents, a new emphasis has been put on heterogeneous chemistry and new projects are carried out in Strasbourg and Grenoble to better understand the role of heterogeneous processes in ozone destruction.

Modelling

A hierarchy of one, two and three dimensional numerical models is being developed and used by several CNRS groups, METEO-FRANCE and ONERA. They played a role in the planning and the interpretation of the major campaigns mentioned above.

Data archives

Before the implementation of the NDSC, ozone profiles by sondes were obtained regularly at Biscarosse. This covers the period 1970-1984 when it was interrupted and replaced by the sondes of OHP. The characteristics of the data base acquired until 1994 is given below. The measurements are going on and planned for obtaining long-term series.

Impact Studies

Impacts of UV-B on heath is being pursued at Institut Gustave Roussy, in several INSERM laboratories and at Fondation Rothschild, with special emphasis respectively on skin cancer, immunology and eye damage.

Recently the Association "Sécurité Solaire" together with Météo-France have started to produce a solar forecast of UV Index, called "Météo solaire". The first experiment was limited to Ile de France in 1994, but since 1995, it is available nationally during summer periods by Minitel.