MST radar (53 MHz) observation of atmospheric polarized scatterers: A great implication for astronomical observations

摘要

The present work reports that the Earth's atmosphere can sometimes exhibit polarized characteristics such that any polarized light coming from the outer space can get modulated easily by these polarized refractive index structures of the atmosphere. Utilizing the Mesosphere Stratosphere Troposphere (MST) radar operating at a very high frequency of 53 MHz in the Indian tropical region of Gadanki, two sets of data are collected for the heights of 2–20 km during (a) 09–10 February 2009 and 06–07 June 2011. The data comprise of atmospheric scattering properties like signal to noise ratio (SNR), Doppler spectral width of the echoes and the atmospheric dynamical parameters like all the three components of wind velocities and their vertical shears. The wind dynamics has been utilized to determine whether the atmosphere was in dynamically unstable conditions that would lead to the generation of turbulence in the atmosphere, Since the MST radar has two sets of 1024 orthogonally polarized antennae aligned along the zonal and meridional directions, it is possible to transmit polarized narrow beams and get echoes accordingly. From these two data sets, one (2009) has been identified as a normally observed echoes and the other data (2011) contain the polarized signals received.