Ionospheric modulations due to solar flares over Ahmedabad

Abstract

Earth’s ionosphere responds quickly to the enhanced X-rays andultraviolet (UV) radiation emitted from the Sun during solar flares. Ground and satellite based observations are important for unravelling the consequencesof these essentially unpredictable events. Regular ionospheric soundings are made over Ahmedabad (23^oN, 72.4^oE) using KEL digital Ionosonde. Using this data, the influence of the excess X-ray emission from the flares / CMEs in different regions of the Earth’s ionosphere over Ahmedabad has been studied. Based on the X-ray spectral characteristics of the flares, the variation in the minimum frequency of reflection, f_min, an indicator of the ionization in D-region of ionosphere, in contrast to daily quiet time variation, has been measured. The studies of the excess absorption, due to the solar flares, in the D-region of ionosphere over Ahmedabad are made for the events during 1996-2000. The deviation from Chapman’s layer behaviour of E-layer over Ahmedabad during few solar flares have been also found.