The main ionospheric trough behavior seen from the in-situ and radio measurements

The main ionospheric trough (MIT) is large structure observed in mid-latitude area of Earth´s ionosphere. It is depleted region of ionospheric plasma typical for the topside ionosphere, especially F layer, where electron density level can significantly decrease as compared to densities measured for adjoining sub-auroral and equatorial regions. The MIT itself and its variability strongly affect the propagation of different natural and artificial signals thus its characteristic is important for radio communication and for communication and space industry in general. We compared data from in-situ measurements collected onboard DEMETER satellite and electron density profiles obtained from radio occultation method used by FORMOSAT-3/COSMIC mission to study the nature of MIT and its behavior during different seasons and magnetic conditions. This paper presents the results obtained in both geographic and magnetic system at fixed local time.