Determinations of plasmasphere electron content from a latitudinal chain of GPS stations

An extended application of a regional method (SCORPION) for calibration of GPS total electron content (TEC) measurements and plasmasphere electron content (PEC) determinations is described and demonstrated for a particular chain of GPS stations, in order to resolve the ambiguity between an omnipresent PEC contribution and the derived receiver system bias. Based on these calibrations and PEC determinations, a latitudinal profile of vertical TEC is presented for North American stations ranging from Alaska to central Mexico, with separate profiles for both the ionosphere (nominally to 1000 km altitude) and the plasmasphere. Determination of the local vertical PEC remedies a latitudinal TEC “sawtooth” feature arising from the standard conversion of slant TEC to equivalent vertical TEC at each station. Comparisons to other TEC methods and measurements, including SCORE, Jason‐1, and IONEX, are also presented. SCORE biases derived for simulated data confirm a latitudinal trend in its bias errors that is also evident in comparisons to SCORPION and Jason‐1. IONEX vertical TEC values are generally greater than the SCORPION vertical TEC values, although the associated comparisons of IONEX to SCORE results indicate that this is primarily a consequence of the conversion from slant TEC to equivalent vertical TEC without separating the ionosphere and plasmasphere components.