A new technique for mapping of total electron content using GPS network in Japan

摘要: The dual frequency radio signals of the Global Positioning System (GPS) allow measurements total number electrons, called electron content (TEC), along a ray path from GPS satellite to receiver. We have developed new technique construct two-dimensional maps absolute TEC over Japan by using data more than 1000 receivers. A least squares fitting procedure is used remove instrumental biases inherent in and Two-dimensional vertical are derived with time resolution 30 seconds spatial 0.15° × latitude longitude. Our method validated two ways. First, TECs paths satellites simulated model for contents based on IRI-95 model. It found that our underestimated less 3 TECU. Then, estimated compared ionospheric calculated simultaneous density profile obtained MU radar. Diurnal day-to-day variation follows behavior radar observation but 2 TECU larger average. This difference can be attributed plasmaspheric path. also applied during magnetic storm September 25, 1998. An intense enhancement, probably caused northward expansion equatorial anomaly, was observed southern part evening main phase storm.