Coupling processes between the ionosphere and the neutral atmosphere play an important role for the dynamics of the upper atmosphere. Recent progress in understanding the related processes has been achieved since low-Earth orbiting satellites provide continuously accurate measurements of thermospheric and ionospheric parameters like mass density, zonal winds and electron density profiles, respectively. Within this project, we plan to observe the global sporadic E occurrence in quantity and also in its quality. The study will be based on GPS radio occultation measurements performed by the satellites CHAMP, GRACE, TerraSAR-X, TanDEM-X and FORMOSAT-3/COSMIC. The database will be extended by measurements of the COSMIC 2 mission that is planned to be launched in spring 2018. Since the launch of CHAMP in 2000, there are currently about 7 millions of radio occultation profiles available. This fact allows to investigate sporadic E properties in a high spatial resolution as well as to perform statistical trend analysis of sporadic E occurrence. The unique global data set including information on sporadic E intensities that was provided during the ongoing project phase of this SPP allows for completely new approaches in the research of the lower ionosphere and its connection to the neutral atmosphere.\\ In this project it is planned to extent the currently existing global climatological study to smaller scale events in time and space in order to receive new insights on coupling processes in the Earth's neutral atmosphere-ionosphere-magnetosphere system like, e.g., the connection between the F- and the E-layer of the ionosphere, and the connection of sporadic E properties with sudden stratospheric warming events. Further we will support the International Reference Ionosphere in order to improve the model's description of the lower ionosphere.