1. Laboratory for Environmental Measurements, Environmental Risks and Safety Division; National Institute of Public Health and the Environment; Bilthoven Netherlands
2. Royal Netherlands Meteorological Institute; De Bilt Netherlands
3. Danish Meteorological Institute; Copenhagen Denmark
4. National Institute of Water and Atmospheric Research; Lauder New Zealand
5. Department of Astronomy; University of Massachusetts; Amherst Massachusetts USA
6. Norwegian Institute for Air Research; Kjeller Norway
7. Institute of Applied Physics; Bern Switzerland
8. Deutscher Wetterdienst; Hohenpeissenberg Germany
9. Central Aerological Observatory; Moscow Russia
10. Alfred Wegener Institute for Polar and Marine Research; Potsdam Germany
11. Instituto Nacional de Técnica Aeroespacial; Torrejon de Ardoz Spain
12. Centre National de la Recherche Scientifique; Paris France
13. Centre National de la Recherche Scientifique; Verrieres-le-Buisson France
14. Norwegian Institute for Air Research; Tromsø Norway
15. Finnish Meteorological Institute; Sodankylä Finland
16. Institut Pierre Simon Laplace; Université de Versailles Saint-Quentin; Verrieres-le-Buisson France
17. Netherlands Environmental Assessment Agency; Bilthoven Netherlands
18. Institute of Meteorology and Water Management; Warsaw Poland
19. European Space Agency; Frascati Italy
20. Institut für Meteorologie und Klimaforschung; Forschungszentrum Karlsruhe; Karlsruhe Germany
21. Space Aeronomy Institute of Belgium; Brussels Belgium
22. Jet Propulsion Laboratory; Wrightwood California USA
23. Meteorological Service of Canada; Toronto Ontario Canada
24. Royal Meteorological Institute of Belgium; Brussels Belgium
25. MeteoSwiss; Payerne Switzerland
26. Department of Physics; University of L'Aquila; L'Aquila Italy