[1] Eotvos Lorand Res Network ELKH, Inst Geol & Geochem Res, Res Ctr Astron & Earth Sci, Budaorsi Ut 45, H-1112 Budapest, Hungary
[2] Czech Acad Sci, Inst Atmospher Phys, Bocni 2 1401, Prague 14100 4, Czech Republic
[3] Natl Inst Earth Phys NIEP, 12 Calugareni St,POB MG 2, Magurele 077125, Romania
[4] Zentralanstalt Meteorol & Geodynam, Hohe Warte 38, A-1190 Vienna, Austria
[5] State Agcy Ukraine, Natl Ctr Control & Testing Space Facil, Main Ctr Special Monitoring, Moscovska 8, UA-01010 Kiev, Ukraine
[6] Eotvos Lorand Res Network ELKH, Inst Earth Phys & Space Sci, Csatkai E U 6-8, H-6400 Sopron, Hungary
[7] Eotvos Lorand Univ, Inst Geog & Earth Sci, Dept Geophy & Space Sci, Pazmany Peter Setany 1-C, H-1117 Budapest, Hungary
[8] CEA, DAM, DIF, F-91297 Arpajon, France