High-latitude thermospheric wind study using a Fabry–Perot interferometer at Tromsø in Norway: averages and variations during quiet times

Abstract

The average winds in the thermosphere during geomagnetically quiet times are important because they provide a baseline wind in the upper atmosphere, but they remain insufficiently understood at high latitudes. This paper reports the first direct ground-based wind measurements of the quiet-time thermospheric wind pattern at Tromsø in Norway using 2009-2015 data from a Fabry-Perot interferometer. We analyzed red-line wind measurements (630.0 nm; altitude: 200-300 km). On average, the zonal wind shows a decrease of eastward wind compared with diurnal tidal wind before midnight. A maximum speed of 100 m/s occurs at both the dusk and dawn sides. The meridional wind has a diurnal tide structure with a minimum value of − 130 m/s around midnight. We also found occasional large wind deviations (> 100 m/s) from the averages, even during geomagnetically quiet times. We suggest that these large wind deviations are caused by the plasma convection associated with weak substorm activities with auroral electrojet (AE) index values of less than 100 nT that occurred at local times different from that at Tromsø.

Thermospheric Wind Response to March 2023 Storm: Largest Wind Ever Observed With a Fabry‐Perot Interferometer in Tromsø, Norway Since 2009

“…After each substorm onset, the acceleration direction of the zonal component turned eastward. This sequence of changes has typically been observed in association with the substorm activity at dusk (Cai et al., 2019; Conde et al., 2001; Oyama et al., 2022; Oyama, Aikio, et al., 2023; Wang, Lühr, Ritter, &, 2012; Wang, Lühr, & Ma, 2012; Wang et al., 2018; Xu et al., 2019). Values of the IL index are not notably large in negative, compared with the past results presented in Figure 6b.…”

“…Winds on the night of March 17 (yellow; before the storm) began from a quiet time level. The zonal component deviates westward after 21 UT or premidnight in the MLT, which is a typical thermospheric wind response to a substorm associated with the westward ionospheric plasma flow at dusk (Cai et al., 2019; Conde et al., 2001; Oyama et al., 2022; Oyama, Aikio, et al., 2023; Wang, Lühr, Ritter, &, 2012; Wang, Lühr, & Ma, 2012; Wang et al., 2018; Xu et al., 2019). The amplitudes of the deviations are within the historical fluctuation range.…”

Spectral Contamination of the 6300 Å Emission in Single‐Etalon Fabry‐Perot Interferometers

“…Many other international installations are unrepresented in this database (e.g., Aruliah et al., 2004; Ford et al., 2008; Ojo et al., 2022; Okoh et al., 2022; Shiokawa et al., 2003, 2012; Yatagai & Oyama, 2016; Yu et al., 2014; Yuan et al., 2010). Intercomparisons of data from various sites are common in the literature (e.g., Billett et al., 2022; Harding et al., 2017; Jiang et al., 2021; Makela et al., 2012, 2014, 2021; Meriwether, 2006; Wu et al., 2014, 2019, Xu et al., 2019). While derived horizontal winds generally compare well qualitatively, quantitative agreement has been challenging, especially for vertical winds and temperatures.…”

IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway

“…Consequently, at high latitudes, traces of ionospheric plasma convection are seen everywhere in the thermosphere. For example, westward thermospheric wind can often be observed in the dusk sector at auroral latitudes, where westward ion drag acts against the background eastward thermospheric wind (Barreto‐Schuler et al., 2021; Cai et al., 2019; Conde et al., 2001; Oyama et al., 2022, 2023; Wang, Lühr, & Ma, 2012b; Wang, Lühr, Ritter, & Kervalishvili, 2012; Wang et al., 2018; Xu et al., 2019).…”