Midlatitude Ionospheric density depletion and its impacts on GNSS

Ionospheric disturbances are the source of accuracy degradation of Global Navigation Satellite System (GNSS) observables and they can cause harm to GNSS positioning techniques, especially for standalone users. The disturbance effects can be rapid and most enhanced by large geomagnetic storm that is still challenging to predict and model. Higher resolution measurement is one of the keys to better understand the storm time impacts on GNSS. During the geomagnetic storm on 17.03.2015, known as St. Patrick’s Day storm, large perturbation of geomagnetic fields was observed even in middle latitudes in European region. In northeast Germany, the largest magnetic disturbances and accompanying plasma density changes were observed from afternoon to evening hours. Multiple GNSS satellites measured unusually large drops of Total Electron Content (TEC) in negative phases of the storm. We demonstrate the performance of GNSS positioning in Single Point Positioning (SPP) and Precise Point Positioning (PPP) techniques for the different phases of ionospheric disturbances. The large errors seems to be occurred when the electron density drops sharply compared to quiet time conditions.