Ionospheric and thermospheric response to the 27–28 February 2014 geomagnetic storm

Abstract

Abstract. The present work explores the ionospheric and thermospheric responses to the 27–28 February 2014 geomagnetic storm. For the first time, a geomagnetic storm is explored in north Africa using interferometer, all-sky imager and GPS data. This storm was caused by coronal mass ejection (CME) associated flares that occurred on 25 February 2014. A Fabry-Perot interferometer located at the Oukaimeden Observatory (31.206° N, 7.866° W, 22.84° N magnetic) in Morocco provides measurements of the thermospheric neutral winds based on the observations of the 630 nm redline emission. A wide angle imaging system records images of the 630-nm emission. The effects of this geomagnetic storm on the thermosphere are evident from the clear departure of the neutral winds from their seasonal behavior. During the storm, the winds experience an intense and steep equatorward flow from 21 to 01 LT and a westward flow from 22 to 03 LT. The equatorial wind speed reaches a maximum of 120 m/s for the meridional component at 22 LT, when the zonal wind reverses to the westward direction. Shortly after 00 LT a maximum westward speed of 80 m/s was achieved for the zonal component of the wind. The features of the winds are typical of TAD (Traveling Atmospheric Disturbances) induced circulation; the first TAD coming from the northern hemisphere reaches the site at 21 LT and a second one coming from the southern hemisphere reaches the site at about 00 LT. We estimate the propagation speed of the northern TAD to be 550 m/s. We compared the winds to DWM07 (Disturbance Wind Model) prediction model and find that this model gives a good indication of the new circulation pattern caused by storm activity, but deviates largely inside the TADs. The effects on the ionosphere were also evident through the change observed in the background electrodynamics from the reversal in drift direction in an observed equatorial plasma bubble. TEC measurements of a GPS station installed in Morocco, at Rabat (33.998° N; 6.853° W, geographic) revealed a positive storm.

ED‐ConvLSTM: A Novel Global Ionospheric Total Electron Content Medium‐Term Forecast Model

“…A G2 class geomagnetic storm that occurred during 27 February-1 March 2014, due to the arrival at the Earth of the shock of a coronal mass ejection (CME) associated with the solar flare event on 25 February 2014 (Malki et al, 2018). Its main phase is during 17:00-23:00 UT, 27 February, and the minimum Dst index reached −97 nT at 23:00 UT, 27 February.…”

Comparison of ICON/MIGHTI and TIMED/TIDI Neutral Wind Measurements in the Lower Thermosphere

“…Thus, fixing TIDI winds based on HWM14 can serve as a fairly straightforward and quick fix until the TIDI zero-wind calibration of the TIDI observations is revised. However, there may be some limitations of using this method because of the known discrepancies between observations and HWM14 (e.g., Malki et al, 2018;Meriwether et al, 2016).…”

Storm‐Time Thermospheric Winds Over Peru

“…We have seen that the DWM07 significantly underestimates, particularly near midnight, the magnitude of the nighttime zonal disturbance winds. Thermospheric wind measurements over the North African lowlatitude region during the 27-28 February 2014 storm showed that the DWM07 also significantly underestimated the nighttime westward disturbance winds near midnight (Malki et al, 2018). Our simple empirical model provides improved estimates of the storm-driven zonal perturbations for the two geomagnetic storms considered above.…”

“…FPI observations from Arequipa showed reductions in the nighttime eastward and poleward winds 24 hr after the onsets of the August 1998 and October 2000 geomagnetic storms (Meriwether et al, 2013). Most recently, Malki et al (2018) reported strong zonal and meridional thermospheric wind perturbations in the westward and equatorward directions around midnight over the northern African sector (31.2°S, 7.8°W, magnetic latitude ~23°N) 6 hr after the onset of the 27-28 February 2014 storm. These results are consistent with predicted delays in the establishment of a steady storm-driven circulation pattern (e.g., Blanc & Richmond, 1980;Richmond & Matsushita, 1975).…”