Influence of seasonal changes on the mid-latitude trough properties

<pre>The sub-auroral region of the main ionospheric trough is a very unique area strongly affected by different type of instabilities coming from both the bottom (Earth's atmosphere) and the top (Earth's magnetosphere) neighbouring regions. The main ionospheric trough’s general characteristics as well as the detailed features change accordingly to the time of day, season, solar cycle and many others. The location of MIT in the latitude-longitude coordinate system throughout the year reflects seasonal changes. Annual variations are observed also in the shape and intensity of the structure. Despite the representation of the structure in the geomagnetic coordinate system, northern and southern trough are not symmetric in the same local season. However some similarities have also been observed. In particular for both hemispheres the structure appears the deepest and well developed during local winter, whereas during local summer the structure becomes hardly visible. Observations show that the MIT tends to shift equatorward for some longitudes in both hemispheres. MIT properties for this study have been derived from DEMETER and COSMIC/FORMOSAT-3 observations.</pre> <p> </p>