Magnetic Observatories and Geomagnetism from the Indian subcontinent and Polar Regions (MOGPR)
Chief Co-ordinator - Prof. Geeta Vichare & Members
The activities under MOGPR program have been classified under three main heads:
(A) Scientific Research,
(B) Instrument Development projects,
(C) Upkeep and Maintenance of Magnetic Observatories, Data Processing, Analysis and Dissemination
The magnetic observatory network spread across the length and breadth of the country has contributed immensely in understanding the dynamics of ionospheric current systems over equatorial, low and high (Antarctica) latitudes, which are governed differently due to variable influence of earth and space processes. The geomagnetic field variations on the surface of the Earth are due to internal as well as external sources. During geomagnetic quiet conditions, currents flowing in the ionosphere such as solar quiet (Sq) and equatorial electrojet (EEJ) mainly contribute as an external source, while long term variations of the geomagnetic field‐ also called as ‘secular variation’, originate inside the Earth's surface. In addition to ionospheric currents, various magnetospheric currents are also seen to form and flow.Equatorial electrojet (EEJ) is an enhanced current flowing close to the equator in a narrow latitudinal belt. The electrojet also controls the electrodynamics of the entire low latitudinal ionosphere. Using ground-based and LEO satellite-based data,IIG researchers have found that the latitudinal width of EEJ varies considerably with longitude. One of the most remarkable discoveries was the four peak structure observed in the longitudinal pattern of the equatorial electrojet, which is attributed to non‐migrating tides. The Indian magnetic observatory network has been utilized to study the Sq current system in detail, such as its intensity, seasonal variation, and latitudinal movement of Sq focus, etc.
A suite of magnetic observatory network along with various experiments over India and Antarctica provides a good comprehensive data-base to explore magnetosphere-ionosphere coupling. A magnetic substorm is a common space weather phenomena observed at Antarctica, which is a short duration disturbance for a period of one to few hours. It is characterized by an explosive energy released from the magnetotail. Substorm occurrences leading to ionospheric particle precipitation at the auroral latitudes cause enhanced absorption of cosmic noise signal, which can be monitored by Riometer. The role of interplanetary conditions in substorm processes and related particle precipitation is a topic of ongoing research. There is not much understanding of drift of energetic charged particles during substorms. With the conjunction of satellite data and advanced ground instruments such as Imaging Riometer and magnetometers, it is possible to investigate as to what wave (EMIC or Chorus or Hiss or ULF) facilitates the loss of particles from the ring current at different local times.Aurora appears as diffused, continuous luminous oval-shaped bands near the geomagnetic poles due to the interaction of energetic particles with the Earth’s atmosphere; while airglow is the emission of photons from atmospheric species excited directly or indirectly by the solar radiation. Extremely and very low frequency (ELF/VLF) electromagnetic waves which are generated by lightning discharges, and man-made transmitters are used along with the Riometer, Airglow, Pulsations, Magnetometer data available at Maitri to understand the complex magnetosphere-ionosphere-atmosphere system.
The Global Electric Circuit (GEC), provides the fundamental coupling system of climatological parameters connecting the electrically disturbed region with fair weather regions. These connections are mainly through the formation of convective clouds and production of thunderstorm and electrified shower clouds. The fair-weather regions exist in the tropical, subtropical as well as in the Polar Regions. The global electrical signals are modulated by the local and regional electrical processes and these variations are different in nature in the tropical/subtropical and polar regions.
Figure : IIG Magnetic Observatorynetworkspreadacrossthelengthandbreadthofthecountry.
