Effects of storm-induced equatorial plasma bubbles on GPS-based kinematic positioning at equatorial and middle latitudes during the September 7-8, 2017, geomagnetic storm

Space weather can impact significantly on the regular equatorial plasma bubbles (EPB) occurrence. During the severe geomagnetic storm on September 7-8, 2017, penetrating electric fields associated with a long-lasting southward IMF supported favorable conditions for EPBs development in the postsunset equatorial ionosphere. The storm-induced EPBs formed rapidly over a broad span of longitudes in the American sector, and further plasma density depletions were streaming away from low latitudes in a northwestward, poleward direction across North America midlatitudes (up to 30 degrees-40 degrees magnetic latitude) toward the main ionospheric trough and auroral irregularity zone. The large-scale storm-induced EPBs and the streamed plasma depletions that persist for several hours can create a localized threat for strong plasma gradients and GPS scintillation effects. We investigated dynamics of the storm-induced irregularities of the equatorial origin and effects of these ionospheric structures on kinematic positioning by combining multi-site ionospheric observations and kinematic solutions for low-earth-orbit GPS and for 4500+ ground-based GPS stations. It was found that the dual-frequency GPS-based positioning accuracy degrades at many GPS stations located from low to middle latitudes of North America, especially within the 25 degrees-35 degrees N area affected by the transported storm-induced plasma depletions and associated irregularities. The estimates of 3D error for the GPS stations in the American longitude sector rose to several meters compared to the normal quiet centimeter-decimeter-level conditions. For the first time, we showed high consistency between GNSS signal phase fluctuations intensity specified by rate-of-TEC change index (ROTI) and accuracy of GPS-based precise positioning for a dense multi-site GPS network in the American sector during such an extreme EPBs development. Analysis of the kinematic and reduced-dynamic orbit solutions for Swarm satellites demonstrated that storm-induced irregularities of an equatorial origin can cause increased up to about 5 times errors in kinematic orbit for LEO satellites, even at midlatitudes.