1. Indian Institute of Geomagnetism (IIG), New Panvel, Navi, Mumbai-410218, India
2. University Department of Physics, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai-400098, India
3. Heliophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD, USA
4. University Corporation for Atmospheric Research, Boulder, CO 80307-3000, USA
5. Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen, Germany