The Effects of IMF B_z Periodic Oscillations on Thermospheric Meridional Winds

Abstract

Previous studies mostly focused on ionosphere and thermosphere responses to strong southward interplanetary magnetic field (IMF) Bz conditions. However, it is not clear how the ionosphere and thermosphere (IT) system responds to Alfvénic quasi‐periodic oscillating IMF Bz conditions. In this article, simulations by the Coupled Magnetosphere Ionosphere Thermosphere model have been used to investigate the effects of IMF Bz temporal variations with 10‐, 30‐, and 60‐min oscillation periods on the coupled IT system. The simulation results show that the cross polar cap potential and auroral peak electron energy flux are stronger when the IMF Bz oscillation frequency is lower. The relatively small periodic wind responses in the 10‐min IMF oscillation case indicates a low‐pass filter nature of the magnetosphere‐ionosphere‐thermosphere system. Two different thermospheric wind (Vn) responses are revealed. One is the almost simultaneous responses at all latitudes, and the other shows a typical traveling atmospheric disturbances signature with a time delay with respect to the latitude for all UTs. The simultaneous Vn responses at all latitudes appear in the daytime Northern Hemisphere, which are mainly caused by the ion drag force in association with penetration electric fields induced plasma density and ion drifts changes. The short‐period traveling atmospheric disturbances occurring in the nighttime of both hemispheres and the daytime of the Southern Hemisphere propagate from high to low latitudes showing latitudinal dependence. Both responses oscillate with the same frequencies as those of IMF Bz oscillations.

WITHDRAWN: Longitudinal variations of noontime thermospheric winds in response to IMF Bz temporal oscillations: broken mean circulation and standing feature

“…In our simulations the maximum PPEF is ~3 mv/m ( Figure not shown), which might be overestimated (Merkin et al, 2005;Wang et al, 2008). As shown in the previous work of Zhang et al (2019), the disturbed wind in the oscillation period of 60 minutes in IMF Bz is strongest when compared to the other two cases with oscillation period of 10 and 30 minutes. Thus, in the present work, we will focus on the 60-min case.…”

“…In the past decades, TADs during magnetic disturbed periods have attracted much attention (e.g., Bruinsma & Forbes, 2007;Liu and Lühr, 2005;Liu et al, 2010Liu et al, , 2014Liu et al, , 2018bOliveira et al, 2017;Otsuka et al, 2004;Shiokawa et al, 2003;Sutton et al, 2009;Thome et al, 1964;Zhang et al, 2019). Previous studies have reported that the storm time energetic particle precipitation and Joule heating (Rodríguez-Zuluaga et al, 2016), the gravity waves (Liu et al, 2014), and the sunset terminator (Beer, 1973) are critical in the generation of TADs.…”

WITHDRAWN: Longitudinal Variations of Noontime Thermospheric Winds in Response to IMF Bz Temporal Oscillations: Broken Mean Circulation and Standing Feature

“…Figure 4 shows the geographic longitude and latitude variations of the disturbed electron density, vertical plasma velocity, meridional plasma velocity, and neutral temperature. The enhancements of wind and temperature at -60°~-180° GLon might be related to the longitudinal patterns of electron density, which have a peak at America sector and causing by the topology of geomagnetic eld (Wang and Zhang, 2017;Zhang et al, 2019). The wind and temperature can be affected by electron density via ion-neutral collision.…”

“…In the past decades, TADs during magnetic disturbed periods have attracted much attention (e.g., Bruinsma & Forbes, 2007;Liu and Lühr, 2005;Liu et al, 2010Liu et al, , 2014Liu et al, , 2018bOliveira et al, 2017;Otsuka et al, 2004;Shiokawa et al, 2003;Sutton et al, 2009;Thome et al, 1964;Zhang et al, 2019). Previous studies have reported that the storm time energetic particle precipitation and Joule heating (Rodríguez-Zuluaga et al, 2016), the gravity waves (Liu et al, 2014), and the sunset terminator (Beer, 1973) are critical in the generation of TADs.…”

“…The thermospheric winds are important factors in the understanding of changes in ionosphere-thermosphere coupling system. In addition, the periodic oscillations of IMF Bz are a common phenomenon seen in the solar wind, which can produce periodic oscillations in the energy and momentum deposition in the upper atmosphere and TADs (e.g., Liu et al, 2018a;Zhang et al, 2019). Taking the abovementioned into consideration, the present work is to study the longitudinal and hemispheric patterns of the meridional wind changes at a xed local time, which…”