Volume 50, Issue 14 e2023GL104334
Research Letter
Open Access

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

S. Oyama

Corresponding Author

S. Oyama

Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan

National Institute of Polar Research, Tokyo, Japan

Correspondence to:

S. Oyama,

[email protected]

Contribution: Conceptualization, Methodology, Software, Formal analysis, Resources, Writing - original draft

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K. Hosokawa

K. Hosokawa

The University of Electro-Communications, Chofu, Japan

Contribution: Validation, Writing - review & editing

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H. Vanhamäki

H. Vanhamäki

Space Physics and Astronomy, University of Oulu, Oulu, Finland

Contribution: Methodology, Validation, Writing - review & editing

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A. Aikio

A. Aikio

Space Physics and Astronomy, University of Oulu, Oulu, Finland

Contribution: Methodology, Validation, Writing - review & editing

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T. Sakanoi

T. Sakanoi

Graduate School of Science Planetary Plasma and Atmospheric Research Center, Tohoku University, Sendai, Japan

Contribution: Methodology, Validation, Writing - review & editing

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L. Cai

L. Cai

Space Physics and Astronomy, University of Oulu, Oulu, Finland

Contribution: Validation, Writing - review & editing

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I. I. Virtanen

I. I. Virtanen

Space Physics and Astronomy, University of Oulu, Oulu, Finland

Contribution: Validation, Writing - review & editing

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K. Shiokawa

K. Shiokawa

Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan

Contribution: Writing - review & editing, Project administration

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N. Nishitani

N. Nishitani

Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan

Contribution: Writing - review & editing

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A. Shinbori

A. Shinbori

Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan

Contribution: Writing - review & editing

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Y. Ogawa

Y. Ogawa

National Institute of Polar Research, Tokyo, Japan

Contribution: Writing - review & editing

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First published: 24 July 2023

Abstract

A thermospheric wind data set from a Fabry-Perot interferometer (630 nm) and the ion velocity from a Dynasonde in Tromsø, Norway, was analyzed for nine winter seasons to study the dynamics of the thermosphere and F-region ionosphere at an auroral latitude. This study focused on bifurcation in the zonal component of the neutral wind and ion velocity at midnight and its dependence on the Y component of the interplanetary magnetic field (IMF). Ionospheric plasma convection patterns are evidently imprinted on the thermospheric wind variations as aspects of the westward and eastward accelerations at dusk and late morning, respectively. The zonal wind bifurcates immediately before midnight for IMF By < 0, but for By > 0, it inverts gradually into the postmidnight sector. Neutral wind streams, originating from higher latitudes, may result in the dependence because of anti-sunward plasma flow distorted in the polar cap.

Key Points

  • The thermospheric wind from a Fabry-Perot interferometer (630 nm) and the ionospheric plasma velocity from a Dynasonde were compared

  • The zonal wind bifurcates immediately before midnight for interplanetary magnetic field By < 0, but for By > 0, it inverts gradually into the postmidnight sector

  • The wind bifurcation signature is different from the ion velocity bifurcation, probably due to advection from the polar cap region

Plain Language Summary

The ionosphere is partially ionized plasma, but the particle minority of ions plays an important role in controlling dynamics of the thermosphere. Particle collision is the fundamental process for momentum transfer from ionospheric ions to thermospheric neutral particles. The ionospheric plasma flow pattern at high latitudes depends on the direction of the interplanetary magnetic field (IMF), and the pattern may be projected on the thermospheric wind. However, the dependence is not yet well understood. This study derived statistical experimental features regarding the dependence of the thermospheric wind, analyzing data from an optical interferometer (Fabry-Perot interferometer) and a radio wave technique (Dynasonde) in Tromsø, Norway. The wind pattern around midnight is different from the ionospheric plasma convection, in accordance with the IMF direction. The zonal wind bifurcates immediately before midnight for IMF By < 0, but for By > 0, it inverts gradually into the postmidnight sector. Neutral wind streams, originating from higher latitudes, may cause the dependence because of anti-sunward plasma flow distortion in the polar cap. In summary, this study concludes that the zonal wind bifurcation at auroral latitudes is caused by the ion velocity bifurcation, and that advection from the polar cap region affects the wind response time to the ion velocity bifurcation.

1 Introduction

In a partially ionized plasma environment, such as the ionosphere, the particle collisional process is a fundamental mechanism that exchanges plasma kinetic energy to the kinetic and thermal energies of neutral particles or vice versa. Ion drag plays a crucial role in the thermospheric wind dynamics at the F-region altitude. 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., 20222023; Wang, Lühr, & Ma, 2012b; Wang, Lühr, Ritter, & Kervalishvili, 2012; Wang et al., 2018; Xu et al., 2019).

According to previous statistical studies on ionospheric plasma flow, the configuration and intensity of the plasma flow pattern are strongly linked to the interplanetary magnetic field (IMF), particularly in the Y-Z plane of the geocentric solar magnetospheric (GSM) coordinates (Förster & Haaland, 2015; Ruohoniemi & Greenwald, 2005; Thomas & Shepherd, 2018). For example, the anti-sunward flow in the polar cap tends to be along the noon-midnight meridian for IMF By < 0 but tilted duskward for IMF By > 0. Therefore, at auroral latitudes, an ionospheric convection border between the dusk and dawn cells appears at later hours for IMF By < 0 than IMF By > 0. A question that comes up naturally is the possibility of the IMF dependence of the thermospheric wind at high latitudes. Simulation studies suggest that the thermospheric dusk convection cell is enhanced more when IMF By is negative than positive (Deng & Ridley, 2006; Hong et al., 2021; Liu et al., 2020). A similar feature was seen in results from statistical analysis of the challenging minisatellite payload (CHAMP) wind measurement (Förster et al., 2011). The Dynamics Explorer (DE) 2 satellite measured thermospheric winds mainly at the dusk-dawn meridian, including the polar cap region. The statistical analysis found that maximum anti-sunward neutral wind in the polar cap appeared at the dusk and dawn side for IMF By < 0 and By > 0, respectively (McCormac et al., 1985; Thayer et al., 1987). This trend is consistent with the statistical features of the ionospheric plasma convection. Following the separation of the ionospheric plasma flow in the midnight sector at auroral latitudes, bifurcation of the thermospheric wind has been observed (Plate 2b of Killeen et al. (1986) and Dhadly and Conde (2017)). However, the IMF dependence of the thermospheric wind at auroral latitudes is not yet well understood.

A scientific objective of this study is to demonstrate the possible IMF dependence of the thermospheric wind at an F-region auroral latitude near magnetic local midnight. Statistical analysis was performed using measurements of the thermospheric wind and the ionospheric ion velocity from a Fabry-Perot interferometer (FPI) and a Dynasonde, respectively, in Tromsø, Norway. The nine winter data set was sorted by the IMF clock angle in GSM Y-Z plane. The statistical results are presented in Sections 3.1 and 3.2. A comparison between the thermospheric wind and ionospheric plasma velocity is presented in Section 3.2 and discussed in Section 4, with a particular focus on changes in individual zonal components near midnight. Note that results from this study are based on observations at a specific auroral latitude in the northern hemisphere. Hemispheric asymmetry of the thermospheric wind response is possible due to, for example, difference in the ionospheric plasma convection patterns (Lukianova et al., 2008; Pettigrew et al., 2010).

2 Measurements

2.1 Thermospheric Wind From an FPI

An FPI has been operating at the European Incoherent Scatter (EISCAT) radar site in Tromsø (69.6°N and 19.2°E in geographic coordinates and 66.7°N in geomagnetic coordinates) during the winter months (mainly from mid-September to early April) since January 2009. Four base points with 45° zenith angles and geographic vertical (i.e., total of five directions) were measured consecutively, with optical filters switched between 557.7 and 630.0 nm during each cycle. In this study, measurements at 630.0 nm were analyzed with an exposure time of 60 s at each position. Including the data transfer time from the charge-coupled device sensor to the hard disk drive, one cycle of the 630-nm measurement in five directions required 315 s. The relatively wide field of view (full width at half-maximum is about 4°) allows more than 10 fringes to be captured simultaneously in each line-of-sight (LoS) fringe image. The Doppler shift or LoS speed is derived from the individual fringes and averaged for each exposure. The statistical standard deviation, which is derived from the averaging procedure, is employed as the measurement uncertainty in this study. Due to the recurrent measurement between 630 and 557.7 nm, vector wind measurements at 630.0 nm, which may have a peak at approximately 240 km altitude, were taken every 780 s (13 min).

Combining data from the four basic positions yields the horizontal component of the thermospheric wind velocity by applying a method described in Shiokawa et al. (20032012) and Figure A1 of Oyama et al. (2023). This method is designed to cancel out the vertical wind and the etalon gap drift in deriving the meridional and zonal components of the wind from a pair of north-south and east-west LoS speeds, respectively. An advantage of this method is that the horizontal wind vector can be estimated without the vertical wind. Measurements under clear skies were used for analysis in reference to the sky condition table available at stdb2.isee.nagoya-u.ac.jp/omti/obslst.html. In this study, nine winter measurements (January 2009 to September 2017) were analyzed (approximately 10,000 data in total).

2.2 Ion Velocity From a Dynasonde

A Dynasonde has been used to estimate the ion velocity in the ionosphere by measuring time series of phase shifts of backscattered echoes from different directions and altitudes. The EISCAT Tromsø Dynasonde applied the ion velocity fit technique to estimate the velocity, using all echoes returned from a virtual range of 300–500 km at frequencies ranging from 2.8 to 8 MHz (Wright & Pitteway, 1994). Dynasonde soundings were performed every 3 min. Ion velocities measured with the EISCAT UHF tristatic method in the F-region were compared to those measured with the Dynasonde and showed good agreement in between (Sedgemore et al., 19961998). In this study, data obtained during the same interval, as the FPI did, were analyzed. The EISCAT radar could also provide the ion velocity, but there was not many simultaneous observation events with the FPI for doing a statistical analysis. Therefore, this study uses the Dynasonde, which is in basically continuous operation.

3 Statistical Results

3.1 Hourly Mean Winds With IMF Separation

Changes in the IMF affect the polar ionosphere through delays. Regarding the ionospheric response time, a long debate is ongoing (e.g., Coxon et al., 2019; Shore et al., 2019). For example, some representative values might be 20 and 60 min in mapping interplanetary conditions from the subsolar magnetopause to the ionosphere (Khan & Cowley, 1999; Laundal et al., 2018, and references therein). However, the response time for the thermosphere is unknown because there have been fewer studies than for the ionosphere. In this study, we tested two averaging windows, which were applied to the IMF data to avoid relying too strongly on fluctuations in instantaneous values, and three response times (20, 40, and 60 min); thus, in total, six patterns, were tested. Figure S1 in Supporting Information S1 describes the procedure in more detail, including the threshold of IMF magnitudes. Since there was no significant difference among the six scenarios (see Figures S2 and S3 in Supporting Information S1), we present results from a response time setting of 60 min, that is, Case 1c, with thresholds of urn:x-wiley:00948276:media:grl66026:grl66026-math-0001 and urn:x-wiley:00948276:media:grl66026:grl66026-math-0002, which is presented in Figure S1 in Supporting Information S1 (all scenarios for Case 1a–1c and Case 2a–2c are described in Supporting Information S1). Note that we do not claim that the thermospheric response time is 60 min, as the tested scenarios showed very similar results.

Figure 1 shows the hourly mean thermospheric wind pattern sorted by the IMF clock angle in the GSM Y-Z plane, which is based on the spacecraft-interspersed, 1-min averaged near-Earth solar wind (OMNI) magnetic field and plasma parameters (Papitashvili & King, 2020). A quiet-time wind pattern was made of measurements under a SuperMAG index, SME (Gjerloev, 2012), less than 40 nT but not sorted by the IMF clock angle (Oyama et al., 2023), which is overlaid in blue. Data number for each time bin is generally smaller at early evening and late morning and larger at midnight. This is because the FPI operation time is determined by the solar zenith angle. Data number is roughly dozens or more (for details, see data downloadable from the repository). As seen in Figure 1, overall patterns of the hourly mean wind look similar for any IMF conditions. For example, dominant equatorward winds are seen from midnight to dawn, southwestward flow at dusk, and westward flow in the late morning hours. However, by subtracting the quiet-time wind, the IMF dependence can be clarified.

Details are in the caption following the image

Statistical thermospheric wind pattern derived from nine-winter Fabry-Perot interferometer (FPI) measurements in Tromsø, Norway. The hourly mean winds were sorted by the interplanetary magnetic field (IMF) clock angle in the geocentric solar magnetospheric Y-Z plane. The quiet-time wind pattern, which was derived from the FPI measurements under SME < 40 nT but with no separation by the IMF clock angle (Oyama et al., 2023), is overlaid in blue. A reference magnitude of the wind vector is illustrated at the top.

Wind deviations from the quiet-time wind pattern, dU, are shown in Figure 2. Since the scientific target of this study is to find a possible imprint of the IMF-dependent ionospheric plasma convection near midnight, this study focuses on zonal dU turning from westward at dusk to eastward at dawn. In general, geomagnetic activity tends to be higher for periods of IMF Bz < 0 than IMF Bz > 0. Since the effects of ion drag are more clearly seen for the southward IMF Bz, we first describe features seen in the case of IMF Bz < 0 and then confirm whether the same features can be seen in the case of IMF Bz > 0. In the case of IMF By < 0, the zonal dU rotates immediately before midnight from westward to eastward. After midnight, the zonal component never reverse westward by the end of measurement in the late morning hours. However, in the case of IMF By > 0, after the westward dU diminishes at midnight, for a few hours, the zonal component is directed weakly westward or almost zero. Stable eastward dU finally appears after 4 MLT. Then, looking at dU patterns for IMF Bz > 0, similar IMF By dependences may be recognized, although features may not be as clear as in the IMF Bz < 0 case. This result is probably due to weaker ion drag effects during the lower geomagnetic activity, which is likely for periods of IMF Bz > 0.

Details are in the caption following the image

Same figure format as Figure 1 but for dU, which was derived from deviations from the quiet-time wind.

3.2 Comparison of the Wind Deviation With the Ion Velocity

The same statistical analysis method as the one employed for the FPI wind (Figure 1) was applied to the Dynasonde-measured ion velocity (Vi). The six schemes to average the IMF data were tested, and there was no significant difference among the results (see Figures S4 and S5 in Supporting Information S1). A method of Case 1c was applied to Vi as in the FPI wind. The hourly mean Vi was sorted by the IMF clock angle and is illustrated in Figure 3 (orange arrows). Features of the ionospheric two-cell convection pattern can be identified at all IMF clock angles. Midnight turning of the zonal Vi, from westward to eastward, appears at a few hours after midnight for IMF By < 0 and immediately before midnight for IMF By > 0. This signature is consistent with the previous statistical analyses of measurements with Super Dual Auroral Radar Network and spacecraft (e.g., Förster & Haaland, 2015; Ruohoniemi & Greenwald, 2005; Thomas & Shepherd, 2018). dU, which was shown in Figure 2, is overlaid in Figure 3 (black arrows). There are remarkable differences between dU and Vi in the midnight sector, particularly in the zonal components. For example, dU is almost perpendicular to Vi at postmidnight hours for IMF By > 0 and at 0 MLT for IMF By < 0. This suggests that in situ ion drag does not play a principal role in controlling the thermospheric wind. That is a notably different signature from the early evening sector, in which approximately same direction can be seen in the two vectors.

Details are in the caption following the image

dU vectors, as shown in Figure 2, are presented in black along with statistical ionospheric ion velocity patterns derived from nine-winter Dynasonde measurements in Tromsø, Norway (orange). Values were sorted by the interplanetary magnetic field clock angle in the geocentric solar magnetospheric Y-Z plane.

4 Discussion

The nine winter data set of the FPI and the Dynasonde measurements at Tromsø, Norway, was statistically analyzed to examine the dependence of the thermospheric and ionospheric flows on the IMF direction in the GSM Y-Z plane. Wind deviations from the quiet-time wind pattern, dU, were derived to investigate the ionospheric forcing that controls the thermospheric wind. This study focuses on zonal dU turning from westward to eastward near MLT midnight, in association with traversing the dusk-dawn ionospheric plasma convection cells at midnight. As presented in Figure 3, an ionospheric convection boundary between the dusk and dawn cells at a Tromsø latitude appears immediately before midnight for IMF By > 0 and a few hours after midnight for IMF By < 0. On the other hand, the wind deviation, dU, does not simply follow the ionospheric pattern as evidenced by the fact that the zonal component turning of dU appears at different time from that of Vi. This discrepancy suggests that other forcings in addition to the ion drag play a crucial role in the wind dynamics at the midnight sector at the auroral latitude.

As seen in Figure 3, for the IMF By < 0 and Bz < 0 case, the zonal component of dU before 23 MLT is westward but turns to eastward at 0 MLT. After turning eastward, dU remains eastward till the end of the FPI measurement. For the IMF By > 0 case, the westward component of dU weakens at 0 MLT, and it takes several hours more until dU becomes stable eastward. Moreover, in the IMF By > 0 case, dU is mainly directed equatorward at post-midnight, although Vi is directed mainly eastward. From midnight to the early morning hours, dU tends to be approximately perpendicular to Vi.

For both IMF By conditions, from midnight to early morning hours, dU is directed approximately equatorward with less reaction to ionospheric dawn cell convection than to the dusk cell convection, at least, at the Tromsø latitude. However, focusing on the zonal component of dU, the westward preference at dusk turns eastward at midnight for IMF By < 0 and remains eastward in the morning sector. For IMF By > 0, the eastward turning of dU appears to take more time after midnight. This result suggests that plasma convection patterns from postmidnight to early morning hours at the Tromsø latitude may be more easily imprinted on dU, although imperfectly, for IMF By < 0 than for IMF By > 0.

We present a hypothesis to generate the equatorward preference of dU and a more clearly visible ionospheric imprint for IMF By < 0. Figure 4 is a schematic drawing of the ion velocity, Vi, (orange) and the wind deviation, dU, (black) for a few hours around midnight. Streams at other time sectors are not illustrated in the figure because this study focuses on features near midnight. Another reason is that IMF dependence of dU has been mainly found around midnight in this study, rather than at the dusk and dawn sectors. The Tromsø latitude is marked by a dashed curve.

Details are in the caption following the image

Model of the ionospheric ion velocity (Vi; orange) and thermospheric wind deviation (dU; black) near midnight for interplanetary magnetic field By < 0 (left) and By > 0 (right) cases. The latitude of Tromsø is marked by a dashed curve.

Before discussing the ionosphere-thermosphere coupling at auroral latitudes, we first introduce the background dynamics in the polar cap region. As reported by previous works, anti-sunward plasma flow in the polar cap can be estimated as more along the noon-midnight meridian for IMF By < 0 than for IMF By > 0 (e.g., Figure 6 in Thomas and Shepherd (2018)). Thermospheric winds in the polar cap can be characterized by the similar trend as the plasma flow, according to the DE 2 and CHAMP measurements (e.g., Förster et al., 2017; McCormac et al., 1985; Thayer et al., 1987).

At premidnight hours, in the dusk ionospheric plasma convection cell, anti-sunward neutral particle streams coming from the polar cap sharply turn westward at auroral latitudes. This change can happen soon after meeting plasma return flows because the horizontal component of the Coriolis and centrifugal forces, acting on the thermospheric westward flow at dusk, tend to cancel each other (Förster et al., 2017). Consequently, the neutral particle stream can be exposed to westward ion drag for several hours (Fuller-Rowell et al., 1984).

Since the zonal component of the hourly mean ion velocity is likely small in the border region between the dusk and dawn plasma convection cells near midnight at auroral latitudes, a continued thermospheric wind from the polar cap can maintain an anti-sunward direction. Applying previous statistical results for the IMF By dependence of the thermospheric wind in the polar cap (Förster et al., 2017; McCormac et al., 1985; Thayer et al., 1987), for IMF By < 0, the anti-sunward neutral particle stream directs almost equatorward in the polar cap at midnight, and the zonal component is nearly null until the stream meets the ionospheric return flow at auroral latitudes. The equatorward neutral particle stream under westward ion drag on the dusk side and eastward on the dawn side swings westward and eastward, respectively, at auroral latitudes. This results in a relatively clear bifurcation of dU at midnight for IMF By < 0.

On the other hand, for IMF By > 0, the thermospheric stream has been tilted slightly westward when reaching auroral latitudes by plasma convection in the polar cap near midnight. The westward component remains for a while at auroral latitudes even after entering the eastward ionospheric plasma convection at dusk, which delays the zonal wind reversal and makes the bifurcation of dU unclear for several hours after midnight.

In any situation of the IMF orientation, at postmidnight hours in the dawn ionospheric plasma convection cell, neutral particle streams, coming from the polar cap region, can pass through the auroral latitudes with less exposure to the eastward ionospheric convection than to the westward ionospheric convection at dusk. The horizontal components of the Coriolis and centrifugal forces add up to the equatorward direction at dawn (Förster et al., 2017; Fuller-Rowell et al., 1984), which builds up the inertia of neutral particle motion equatorward. Consequently, in the postmidnight sector, the eastward ion drag at auroral latitudes can act on the neutral particle streams for a shorter time than the westward ion drag at dusk. For the IMF By < 0 case, since the anti-sunward thermospheric wind in the polar cap is directed almost equatorward, dU can be directed slightly eastward by ion drag, although the equatorward component is still dominant.

In summary, dU bifurcation can appear close to 0 MLT for the IMF By < 0 case. On the other hand, for the IMF By > 0 case, eastward turning of dU requires more time because of the westward-tilted neutral and plasma flows in the polar cap, resulting in delay of the dU bifurcation. The zonal wind bifurcation at auroral latitudes is caused by the ion velocity bifurcation, while advection from the polar cap region affects the response time of thermospheric wind to the ion velocity bifurcation.

5 Conclusions

Statistical analysis was conducted for nine winter measurements from an FPI (wavelength of 630 nm) and a Dynasonde in Tromsø, Norway, to study the dependence of the thermospheric wind (U) at approximately 240 km altitude and the ionospheric plasma velocity (Vi) on the IMF clock angle in the GSM Y-Z plane. In this study, we calculated wind deviations (dU) from the quiet-time wind pattern to highlight variations due to external forcings. This study focused on westward to eastward zonal thermospheric wind changes near midnight. The zonal bifurcation of dU appears immediately before midnight for the IMF By < 0 case. On the other hand, for the IMF By > 0 case, the zonal component gradually inverts from westward to eastward in the postmidnight sector. This study is the first to report the IMF dependence of the thermospheric wind near midnight at an F-region auroral latitude.

From midnight to early morning hours, dU is directed preferentially equatorward, despite of eastward-dominant Vi, which suggests that in situ ion drag does not play a principal role in controlling the thermospheric wind at auroral latitudes for this time sector. The cause of the dU deviation from Vi may be related to the integrated ion drag effect in the polar cap, as the air travels from dayside to the nightside. For the IMF By < 0 case, the accelerated wind in the polar cap can be almost parallel to the noon-midnight meridian, as is the ionospheric plasma flow, and reaches auroral latitudes with a small zonal component on average. On the other hand, for the IMF By > 0 case, the accelerated wind in the polar cap is tilted slightly westward when reaching the auroral latitudes due to distortion of the ionospheric plasma convection cells. The flow angle difference when reaching auroral latitudes in the midnight-early morning sector and the time-of-passing through the auroral oval can result in the observed IMF By dependence on dU.

Note that this study is confined to the Tromsø latitude, that is, an auroral latitude in the northern hemisphere. IMF clock-angle dependence of the thermospheric wind at auroral latitudes may be different in the southern hemisphere due to, for example, differences in the ionospheric plasma convection pattern (Lukianova et al., 2008; Pettigrew et al., 2010). A similar analysis as performed in this study should be applied to datasets obtained in the southern hemisphere. Such study will be helpful to understand more about the energy dissipation process in the high-latitude upper atmosphere during solar-wind variations, which can be different between hemispheres.

Acknowledgments

We gratefully acknowledge the EISCAT Scientific Association which operates the Tromsø Dynasonde (dynserv.eiscat.uit.no). This work was supported by JSPS KAKENHI JP 16H06286, 21H04518, 21K18651, 21KK0059, 22H01283, 22H00173, and 22K21345. H. V. was partially supported by Academy of Finland AF314664. This work was conducted by the joint research program of Planetary Plasma and Atmospheric Research Center, Tohoku University.

    Data Availability Statement

    The IMF and the SME data were obtained from the OMNI database (https://doi.org/10.48322/45bb-8792) and SuperMAG webpage (supermag.jhuapl.edu/indices and go to a tag of “Download Indices”), respectively. The FPI and Dynasonde mean data used for figures in the study are available at the Nagoya University Repository with open and free access (https://doi.org/10.18999/2005071).