High‐resolution station‐based diurnal ionospheric total electron content (TEC) from dual‐frequency GPS observations

Abstract

AbstractTotal electron content (TEC) estimates derived from Global Navigation Satellite System (GNSS) signal delays provide a rich source of information about the Earth's ionosphere. Networks of Global Positioning System (GPS) receivers data can be used to represent the ionosphere by a Global Ionospheric Map (GIM). Data input for GIMs is dual‐frequency GNSS‐only or a mixture of GNSS and altimetry observations. Parameterization of GNSS‐only GIMs approaches the ionosphere as a single‐layer model (SLM) to determine GPS TEC models over a region. Limitations in GNSS‐only GIM TEC are due largely to the nonhomogenous global distribution of GPS tracking stations with large data gaps over the oceans. The utility of slant GPS ionospheric‐induced path delays for high temporal resolution from a single‐station data rate offers better representation of TEC over a small region. A station‐based vertical TEC (TECV) approach modifies the traditional single‐layer model (SLM) GPS TEC method by introducing a zenith angle weighting (ZAW) filter to capture signal delays from mostly near‐zenith satellite passes. Comparison with GIMs shows the station‐dependent TEC (SD‐TEC) model exhibits robust performance under variable space weather conditions. The SD‐TEC model was applied to investigate ionospheric TEC variability during the geomagnetic storm event of 9 March 2012 at midlatitude station NJJJ located in New Jersey, USA. The high temporal resolution TEC results suggest TEC production and loss rate differences before, during, and after the storm.