1. IAASARS, National Observatory of Athens (NOA), 15236 Athens, Greece
2. Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
3. Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece
4. Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15784 Athens, Greece
5. Department of Geography, Harokopion University of Athens, 17671 Athens, Greece
6. Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
7. IERSD, National Observatory of Athens, 15236 Athens, Greece
8. Physics and Meteorology Observatorium of Davos, World Radiation Center, 7260 Davos, Switzerland
9. Leibniz Institute for Tropospheric Research, 04318 Leipzig, Germany
10. National Institute of Research & Development for Optoelectronics (INOE), 77125 Magurele, Romania
11. The Cyprus Institute, Nicosia 2121, Cyprus
12. Center for Atmospheric Research, University of Nova Gorica, 5600 Ajdovščina, Slovenia
13. Department of Meteorology, University of Reading, Whiteknights, Reading RG6 6ET, UK
14. Institute of Applied Geosciences, Technical University of Darmstadt, 64289 Darmstadt, Germany