| Session Details | |
| Section | ST - Solar & Terrestrial Sciences AS - Atmospheric Sciences |
| Session Title | ELF-VLF Remote Sensing of the Ionosphere and Magnetosphere |
| Main Convener | Dr. Rajesh Singh (Indian Institute of Geomagnetism, India) |
| Co-convener(s) | Prof. Sandip Kumar Chakrabarti (S.N. Bose National Centre for Basic Sciences, India) Dr. Abhay Kumar Singh (Banaras Hindu University, India) Dr. Morris B Cohen (Stanford Univeristy, United States) Dr. Bhaskara Veenadhari (Indian Institute of Geomagnetism, India) |
| Session Description | Extremely Low Frequency (ELF, 30-3000 Hz) and Very Low Frequency (VLF, 3-30 kHz) waves are powerful tools for remote sensing of processes in the ionosphere and magnetosphere. ELF-VLF waves have their origin in both natural (e.g., lightning) and man-made (e.g., VLF transmitters) sources. For past several decades satellite and ground based observations of whistlers and VLF emissions all over the globe is been used as an important diagnostic tool to understand the dynamical process in complex ionosphere and magnetosphere. In addition, it is well known that the radiations from the lightning discharge and VLF transmitters are reflected from the lower boundary of the D-region ionosphere and travel very long distances in the Earth-ionosphere wave guide with a very little attenuation. This property makes VLF waves one of the most important tools to study the ionosphere in the height range of ~ 60-90 km – the D-region. It is the region of the ionosphere difficult to monitor continuously, the reason being height range of D-region ionosphere which can not be accessed by balloon probes and neither can be scanned by satellites to give reasonable measurements nor by radars. Thus VLF waves find its application as the important tool to study D-region ionosphere continuously during quiet and disturbed geophysical conditions. Recent studies have also shown the evidence of ionospheric anomalies due to Earthquakes because of energy coupling in lithosphere-ionosphere system. Paper contributions are invited to this special session which concentrate on experiment, observation, theoretical, and numerical studies on phenomena like lightning discharges, radio atmospherics/tweeks, whistlers, VLF emissions etc. and D-region ionospheric perturbations by phenomena such as transient luminous events (TLE’s), lightning induced electron precipitation (LEP's), cosmic gamma-ray flares, terrestrial gamma ray flashes (TGF's), solar flares, solar eclipses, geomagnetic storms, etc. --- This will be combined with other work on VLF waves as follows: --- The region between 40km to 250km cannot be studied by balloons or space crafts and thus must be studied by very low frequency (VLF) radio waves. VLF can be used in studying the response of the ionosphere due to terrestrial and extra-terresterial disturbances involving ionizing radiation. A large number of workers found evidences that even lithosphere-ionosphere coupling causes ionospheric anomalies before earthquakes. Intensity variations during solar flares, solar eclipses, and due to gamma ray bursts and soft gamma-ray repeaters cause variations in ionospheric activities. In this session we bring together the scientists to present their experiences in ionospheric anomalies due to earthquakes, and high energy phenomena and theoreticians to understand these anomalies. Thsi is very relevant for the Asia Pacific region. |