Ionospheric impact on GNSS signals

Abstract

Space weather can adversely affect accuracy, reliability and availability of global navigation satellite systems (GNSS). To be aware of the space weather impact on navigation signals in the L- band, a permanent monitoring of the ionospheric behavior is required in precise and safety of life applications. Enhanced ionization level of the ionosphere increases also ionospheric range errors. Whereas dual frequency GNSS measurements enable mitigating first order errors, higher order errors do not cancel out by combining the signals at both frequencies. Space weather events affecting the ionospheric plasma distribution may degrade the navigation information or even the electromagnetic signal itself. We discuss several space weather effects in the ionosphere such as strong perturbations in plasma density and distribution using ground and space based GNSS measurements. The temporal variation of high latitude TEC data extracted from polar TEC maps indicate a close correlation of TEC fluctuations not only with geomagnetic activity indices but also with particle flux data.