Cycle-related solar vacuum ultraviolet (VUV) variability

The solar vacuum ultraviolet (VUV) radiation is the main source of energy for the Earth's middle and upper atmosphere and controls many aeronomic processes. In addition, it provides us crucial information about the physical processes in the solar atmosphere. Despite its importance, the records of VUV measurements is limited to the space age, since the radiation in this wavelength range is absorbed in the Earth's atmosphere and its measurement is possible only through satellite-based observations.

Various studies has shown that the Sun was in an extremely inactive state during the prolonged minimum of the cycle 23 compared to other recent minima. Following these studies, in this thesis work, it was tried to have a closer look at the variability of the quiet Sun network and internetwork radiance between the last two solar minima. The aim of this dissertation is to find out whether there is a change in the radiance properties of the upper chromosphere and transition region (at some specific wavelengths of the VUV spectrum), over the last solar minimum.