Ionospheric topside Scale Height for Space Weather monitoring

Abstract

Space Weather refers to phenomena that arise from the connection between the Sun and Earth and can have adverse effects on the operation of technical systems and human activities. The Sun is rapidly approaching solar maximum currently, the technical systems are particularly vulnerable to rapid changes in the electron density distribution in the topside ionosphere and plasmasphere that can arise from space weather. Since ionospheric slab thickness is a measure of the shape of the electron density distribution, accurate modelling and monitoring of slab thickness can help prediction of space weather impact. Indeed, the profile shape reflects the complexity of production, loss and transportation of plasma in the Earth’s ionosphere and plasmasphere. A proxy Slab-Thickness for the topside ionosphere/plasmasphere is computed by dividing the topside vertical total electron content (TEC) data derived from GNSS navigation measurements by the in-situ electron density data from the Langmuir Probes (LP). The idea is very similar to the computation of equivalent slab-thickness dividing the ground TEC by the peak electron density measurements from vertical sounding or radio occultation data (see Jakowski and Hoque 2021). Single satellite measurements can be used; however, since Swarm-A and -C satellites are flying close-by both satellites data can be combined for improved products. The derived quantity will accurately provide a proxy measure of the topside ionosphere/plasmasphere (profile) thickness. From the long-term database of proxy Slab-Thickness a slab-thickness model can be developed. Existing ionosphere models (e.g., IRI, NeQuick, NEDM2020) will be benefitted using topside slab-thickness information. The data as well the model can be used to verify the properties of equivalent slab-thickness and ionosphere/plasmasphere coupling found by Jakowski and Hoque (2021, 2018). A bulge like increase of slab-thickness at around middle latitude (~40°) especially during night time is found which is first reported by Jakowski and Hoque (2021) in ground data. Many unanswered questions regarding ionosphere/plasmasphere coupling processes may be solved by simultaneously analysis of ground slab-thickness and topside proxy slab-thickness data. During space weather events the TEC and LP data will be changed in a nonlinear way and therefore the proxy slab-thickness value can be used a monitor for space weather events.

References: Jakowski N, Hoque MM. 2018. A new electron density model of the plasmasphere for operational applications and services. J. Space Weather Space Clim. 8: A16 Jakowski N & Hoque MM 2021. Global equivalent slab thickness model of the Earth’s ionosphere. J. Space Weather Space Clim. 11, 10. https://doi.org/10.1051/swsc/2020083