SPACE WEATHER IMPACT ON SATELLITE NAVIGATION AND POSITIONING

Abstract

Space weather can adversely affect accuracy, reliability and availability of global navigation satellite systems (GNSS) in different ways. GNSS satellites can be direct subject to damage by high energetic particles or radiation. Furthermore, enhanced solar radio emission can interfere with GNSS signals and solar wind enhancements can considerably disturb the propagation of navigation signals in the ionosphere. Single frequency GNSS measurements require a correction of the ionospheric range error. Modeling and monitoring of related errors contribute to mitigate the ionospheric impact on GNSS In dual frequency GNSS systems space weather related ionospheric perturbations must be taken into account on a broad range in magnitude at quite different scales reaching from small scale plasma turbulences in the meter domain up to large scale ionization fronts in the 1000 km range. Thus, ionospheric perturbations can considerably reduce the achievable accuracy in precise positioning applications, whereas in safety of life applications such as aircraft landing in aviation, the protection level might be violated. To reduce the space weather impact on those applications and to enable correction or mitigation of ionospheric effects, continuous monitoring of the ionospheric behavior is required e.g. by measuring the Total Electron Content (TEC). Thus, augmentation systems such as WAAS in US and EGNOS in Europe and ionospheric services such as SWACI provide correction information and messages concerning the current and predicted perturbation degree of the ionosphere. Much work has still to be done to fulfill customers’ requirements on accuracy and reliability of forecast quality.