Ionospheric effects of a solar wind high-speed stream driven geomagnetic storm

Solar wind high-speed streams (HSSs) and associated stream interaction regions (SIRs) typically produce long-lasting, but only moderate or weak geomagnetic storms. In this presentation, we will focus on electron density (Ne) and total electron content (TEC) changes at high to middle latitudes and associated physical processes during a specific HSS/SIR driven storm. The very long-lasting storm was produced by two interacting high-speed streams. Both enhancements, but in specific long-lasting (days) decreases of Ne and TEC are observed by the EISCAT radars and GNSS observations, respectively. Observational data sets also include AMPERE field-aligned current data, SuperDARN convection maps, and TIMED/GUVI observations of the O/N2 ratio.e