Multi-instrument observations of storm-enhanced density during geomagnetic storms

Ionospheric electron density and the total electron content (TEC) are representative and highly variable electromagnetic parameters in the coupled magnetosphere-ionosphere system. Because our modern society increasingly relies on ground-to-ground and ground-to-space communications and navigation, understanding the sources of the ionospheric density variability and monitoring its dynamics during space weather events have great practical importance. During geomagnetically disturbed times, ground-based instruments, such as incoherent scatter radars (ISRs) and GPS receivers, have observed great electron density and TEC enhancements and depressions over a wide range of magnetic latitudes and local times. We present observations of Storm-Enhanced Density (SED) [1] from the Poker Flat Advanced Modular ISR and GPS TEC during multiple geomagnetic storms. In particular, we show in detail the temporal evolution of SED observed during the Oct. 24-25, 2011 geomagnetic storm and discuss the mechanisms for the formation of SED [2]. Other key ionospheric properties, such as the convection flows and plasma temperature, within and surrounding these density structures are also presented and their relationship to the electron density and TEC changes are discussed.