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The Feature Tracking of Aurora (FTA) model was constructed using 1.5 years of Polar Ultraviolet Imager data and is based on tracking a cumulative energy grid in 96 magnetic local time (MLT) sectors. The equatorward boundary, poleward boundary, and 19 cumulative energy bins are tracked with the energy flux and the latitudinal position. With AE increasing, the equatorward boundary moves to lower latitudes everywhere, while the poleward boundary moves poleward in the 2300-0300 MLT region and equatorward in other MLT sectors. This results in the aurora getting wider on the nightside and becoming narrower on the dayside. The peak intensity of the aurora in each MLT sector is almost linearly related to AE, with the global peak moving from pre-midnight to post-midnight as geomagnetic activity increases. Ratios between the Lyman-Birge-Hopfield-long and -short models allow the average energy to be calculated. Predictions from the FTA and two other auroral models were compared to the measurements by the Defense Meteorological Satellite Program Special Sensor Ultraviolet Spectrographic Imagers (SSUSI) on March 17, 2013. Among the three models, the FTA model specified the most confined patterns with the highest energy flux, agreeing with the spatial and temporal evolution of SSUSI measurements better and predicted auroral power (AP) better during higher activity levels (SSUSI AP > 20 GW). The Fuller-Rowell and Evans (1987) and FTA models specified very similar average energy compared with SSUSI measurements, doing slightly better by ~1 keV than the OVATION Prime model. [ABSTRACT FROM AUTHOR]

We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 and X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at the Earth accompanied by enhancements of MeV‐range energetic particle flux in both the solar wind (SEP event) and inner magnetosphere, and an AL < −2,000 substorm took place. (1) Both X flares caused enhancement of ionospheric electron density for about 10 min. The X9.3 flare also increased temperatures of both electrons and ions over 69°–75° geomagnetic latitude until the X‐ray flux decreased below the level of X‐class flares. However, the temperature was not enhanced after the previous X2.2 flare in the prenoon sector. (2) At around 75° geomagnetic latitude, the prenoon ion upflow flux slightly increased the day after the X9.3 flare, which is also after the first ICME and a SEP event, while no outstanding enhancement was found at the time of these X flares. (3) The upflow velocity sometimes decreased when the interplanetary magnetic field (IMF) turned southward. (4) Before the first ICME arrival after the SEP event under weak IMF with Bz ~0 nT, a substorm‐like expansion of the auroral arc signature took place without local geomagnetic signature near local midnight, while no notable change was observed after the ICME arrival. (5) AL reached <−2,000 nT only after the arrival of the second ICME with strongly southward IMF. Causality connections between the solar/solar wind event and the ionospheric responses remain unclear. Key Points: The X9.3 flare on 6 September 2017 triggered enhancements of ionospheric electron density and temperature but not ion upflow immediatelyPrenoon ion upflow at 400 km altitude increased over 6–8 September 2017, but its cause can be SEP event rather than CME or X flareSubstorm‐like auroral breakup was observed without notable geomagnetic signature when the interplanetary magnetic field was very weak [ABSTRACT FROM AUTHOR]