Underutilized Spaceborne GPS Observations for Space Weather Monitoring

Many of currently operated low Earth orbit satellites, in particular Earth observing meteorological missions, are equipped with dual-frequency Global Positioning System (GPS) receivers with a zenith-looking antenna for tasks of precise orbit determination and timing. The already existed databases with accumulated raw GPS measurements, as a by-product of satellite missions, can arouse specific interest for ionospheric and space weather community too. We demonstrate potential possibilities and advantages of involving underutilized spaceborne GPS measurements for Space Weather activity monitoring by specification of storm-induced ionospheric plasma density irregularities at different altitudinal domain of the topside ionosphere. We have analyzed a dynamical response of the high-latitude topside ionosphere to the intense geomagnetic storm of 19–21 December 2015 using up-looking GPS measurements on board Swarm and Meteorological Operational satellite (MetOp) missions, flying at altitudes of ~500 km and ~835 km, respectively. For the first time, GPS observations on board the meteorological mission MetOp were used to reveal an occurrence of plasma irregularities at altitudes above 835 km. Our results demonstrate that during strong geomagnetic storms the intense plasma density irregularities can occur in the topside ionosphere near ~500 km altitude and can be still persisted above 835 km. Joint analysis of the Super Dual Auroral Radar Network global convection patterns, ground-based GPS total electron content (TEC) observations, and MetOp-derived topside TEC observations confirmed that plasma irregularities above ~835 km coincided with the plasmaspheric/magnetospheric part of the storm-enhanced density and the polar tongue of ionization structures, which is the first direct observation of the storm-enhanced density/tongue of ionization structure in the plasmaspheric TEC.