Department of Applied Geophysics, Faculty of Science, Charles university in Prague, Albertov 6, Prague 2, 12843 Czech Republic; Department of Applied Geophysics, Faculty of Science, Charles university in Prague, Rozvojova 135, Prague 6, 16502 Czech Republic
Faculty of Science, University of Nice, Nice, Nice, 00000 France
Division of Geophysics, Department of Physical Sciences, University of Helsinki, P.O. BOX: 64, Helsinki, 00014 Finland
Department of Physics, Catholic University of America, Washington, Washington DC, DC 00000, USA; NASA Goddard Space Flight Center, Code 691, Greenbelt, MD 00000, USA
Division of Geophysics, Department of Physical Sciences, University of Helsinki, P.O. BOX: 64, Helsinki, 00014 Finland