SuperDARN Observations During Geomagnetic Storms, Geomagnetically Active Times, and Enhanced Solar Wind Driving

The Super Dual Auroral Radar Network (SuperDARN) was built to study ionospheric convection at Earth and has in recent years been expanded to lower latitudes to observe ionospheric flows over a larger latitude range. This enables us to study extreme space weather events, such as geomagnetic storms, which are a global phenomenon, on a large scale (from the pole to magnetic latitudes of 40°). We study the backscatter observations from the SuperDARN radars during all geomagnetic storm phases from the most recent solar cycle and compare them to other active times to understand radar backscatter and ionospheric convection characteristics during extreme conditions and to discern differences specific to geomagnetic storms and other geomagnetically active times. We show that there are clear differences in the number of measurements the radars make, the maximum flow speeds observed, and the locations where they are observed during the initial, main, and recovery phase. We show that these differences are linked to different levels of solar wind driving. We also show that when studying ionospheric convection during geomagnetically active times, it is crucial to consider data at midlatitudes, as we find that during 19% of storm time the equatorward boundary of the convection is located below 50° of magnetic latitude. Plain Language Summary During geomagnetic storms, electrical currents which flow in space around the Earth change the magnetic field we measure at Earth. We use this to identify storms and look at how measurements from radars during the storm phases compare to other times when the disturbance of the geomagnetic field is similar, as well as during times when the solar wind (which drives the storms) is high and behaves similarly as to storms. The radars we use are located at high latitudes and are purposely built to measure ionospheric convection. We find that the ionospheric convection during the main phase of a storm spans to much lower latitudes than previously thought: 40 degrees of magnetic latitude. We also show that the initial and recovery phases of a geomagnetic storm show similar ionospheric convection as periods when enhanced solar wind driving, but no geomagnetic storm occurs. Whereas the main phase of a storm shows a faster moving and more disturbed ionosphere. The initial and recovery phase show similar behavior, whereas the main phase of a storm shows higher ionospheric convection due to higher solar wind driving. Key Points During geomagnetic