|INDIAN INSTITUTE OF SCIENCE EDUCATION & RESEARCH, MOHALI|
INSPIRE Faculty (Earth and Environmental Sciences)
Knowledge city, Sector 81, SAS Nagar,
Manauli PO 140306
I am interested in the processes and phenomena occurring in the upper atmosphere and ionosphere of earth (approximately within 50 and 1000 km altitudes from the surface). This region includes both the coldest mesopause existing around 100 km with temperatures around 170K and the hottest upper thermosphere above 250 km with temperatures of 1000 - 2000K. A part of the upper atmosphere ionizes due to extreme ultraviolet radiations from the sun resulting in the formation of ionosphere. The density of the upper atmosphere is feeble enough to avoid frequent collisions so that the ionosphere exists all through the night, albeit with decreasing ion densities. With increasing dependence on satellite based technologies, understanding this region is very important as it affects the radio communications. Further, several low earth orbiting satellites and the International Space Station are placed herein. The solar transients have noticeable impact in this region and they frequently affect this region. Furthermore several interesting phenomena like frictional burning of meteors and formation of auroras occur in the upper atmospheric region.
I am particularly interested in studying the role of waves and instabilities in the upper atmosphere and ionosphere. Waves play an important role in transferring energy between different parts of the atmosphere in both horizontal and vertical dimensions. Therefore they are key participants determining the coupling between different regions of atmosphere and the coupling between atmosphere and ionosphere as well. Moreover, they are instrumental in the formation of instabilities which leads to turbulence. The information loss occur when instabilities are generated in the ionospheric plasma resulting in electron density irregularities which scatters the radio waves in a random manner. I primarily utilize the data obtained by observing faint atomic and molecular emissions emanating from the upper atmosphere called 'airglow'. In addition data from other radio and optical remote sensing methods, in-situ satellite measurements and empirical models are used to investigate the dynamical and electrodynamical processes ongoing in the upper atmosphere region.