Ionospheric Sounding and Tomography Using Automatic Identification System (AIS) and Other Signals of Opportunity

Abstract

Abstract Numerical modeling has demonstrated that Automatic Identification System (AIS) signals can be used not only to estimate vertical total electron content (TEC) to supplement current TEC maps and data assimilation models but also to reconstruct two‐dimensional (2‐D) electron density maps of the ionosphere using computerized tomography. A ray tracing model was used to determine the characteristics of individual linearly polarized waves transmitted by ships to satellites in circular orbits at 780‐ and 1,000‐km altitude, including the wave path and the state of polarization at the satellite receiver. The modeled Faraday rotation was computed and used to calculate the TEC along the ray paths. The resulting TEC was used as input for computerized ionospheric tomography using the algebraic reconstruction technique. This study concentrated on reconstructing mesoscale structures 25–100 km in horizontal extent. The primary scientific interest of this study was to show that AIS signals can be used as a new source of input data for computerized ionospheric tomography to image the ionosphere and to obtain a better understanding of magneto‐ionic wave propagation.