Analysis of Large and Extreme Global Total Electron Content

Abstract:

Ionospheric disturbances, due to photoionization and energetic particle precipitation, occurring both on a regular recurring basis, and heightened due to space weather, impact global position, navigation, and timing services provided by, for example, the Global Navigation Satellite System (GNSS). The development of operational services to mitigate the risks to users requires knowledge on how space weather impacts critical systems, and the frequency and magnitude of extreme events. Systems sensitive to ionospheric propagation delay errors specifically benefit from an analysis of large and extreme total electron content (TEC). In this study, twenty years of global TEC maps are analyzed to determine the global distribution of the maximum TEC. Maximum TEC is shown to reach magnitudes of up to >200 TECU in extreme cases, with the largest overall TEC located at equatorial latitudes. A generalized extreme value distribution was applied to the daily maximum TEC globally and for the high, mid, and low-latitude regions to determine the 1-in-44 year (4 solar cycles) and 1-in-100 year maximum TEC with a 99% confidence interval. Additionally, the return period for TEC thresholds defined for safe operation by the International Civil Aviation Organization are discussed. Extreme values provide criteria for the development of operational systems and vulnerability assessment of critical systems dependent on GNSS.