1. Institute of Astronomy, Astrophysics, Space Applications and Remote Sensing,National Observatory of Athens (IAASARS-NOA),Penteli,Greece
2. Leibniz Institute for Tropospheric Research (TROPOS),Leipzig,Germany
3. Istituto di Metodologie per l’Analisi Ambientale (CNR-IMAA),Consiglio Nazionale Delle Ricerche,Tito Scalo,Italy
4. Finnish Meteorological Institute (FMI),Helsinki,Finland
5. European Space Agency (ESA- ESTEC),Noordwijk,The Netherlands
6. Climate and Environmental Research Institute NILU,Kjeller,Norway
7. National Institute of Research and Development for Optoelectronics - INOE,Magurele,Romania,2000