Upper Thermospheric Winds

Wang, Wenbin; Burns, A. G.; Liu, Jing

doi:10.1002/9781119815631.ch3

Cited by 14 publications

(15 citation statements)

References 95 publications

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“…Due to the geometry of the Earth's geomagnetic field, neutral winds at lower latitudes can generate electric fields via the dynamo effect and push the ionospheric plasma upward and downward along the magnetic field lines (e.g., Immel et al., 2021; Kelly, 1989; Rishbeth, 1972). At high latitudes, they feed back into the ionospheric convection and can transport energy and momentum from high to low latitudes (e.g., Dhadly & Conde, 2017; Killeen, 1987; Killeen & Roble, 1986; Richmond et al., 2003; Wang et al., 2021). In the mesosphere and lower thermosphere (MLT, 60–110 km), where most tides and waves dissipate, neutral winds control the energy and momentum entering the upper atmosphere via gravity waves, tides, and planetary waves from the underlying regions (including the troposphere, stratosphere, and lower mesosphere; e.g., Forbes, 2007; Forbes et al., 2006; Lindzen, 1981; Smith, 1996, 2004; Yiğit et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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The Earth's upper atmosphere is a dynamic environment and neutral winds are a critical component of it. Neutral winds control a large part of the dynamics within the coupled upper atmosphere and ionosphere system and thus plays an important role in determining the state of the ionosphere-thermosphere (I-T) system at all latitudes. Due to the geometry of the Earth's geomagnetic field, neutral winds at lower latitudes can generate electric fields via the dynamo effect and push the ionospheric plasma upward and downward along the magnetic field lines (e.g.,

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Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…The enhancement of the Joule heating, ion drag, and Lorentz force can also modulate the energy and momentum budgets of the residual circulation system during geomagnetically disturbed times. It would cause a complicated residual wind system yet more dynamic (Kwak & Richmond, 2021; W. Wang et al., 2021). This topic will be the subject for future studies.…”

Section: Discussion and Summarymentioning

confidence: 99%

The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 1. Driving Mechanism

et al. 2022

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In this study, the mechanism driving the narrow lower‐thermospheric winter‐to‐summer meridional circulation is thoroughly investigated for the first time using the Specified Dynamics configuration runs of the Whole Atmosphere Community Climate Model eXtended (SD‐WACCMX) simulations and the TIMED Doppler Interferometer (TIDI) observations. The mean meridional circulation in the SD‐WACCMX is qualitatively consistent with the TIDI measurements, though the magnitude in the SD‐WACCMX is about 50% weaker. The lower‐thermospheric winter‐to‐summer circulation is mainly driven by the resolved wave forcing, including the tides and internally generated inertia gravity waves (GWs). The momentum forcing from the parameterized sub‐grid scale GWs is not as significant as the resolved wave forcing in driving the lower‐thermospheric meridional circulation. The GW parameterization scheme in the SD‐WACCMX only includes GWs with phase velocities in the range of ±45 m/s, which might result in most of the parameterized sub‐grid GWs dissipating and breaking in the mesosphere and hardly impacting the lower thermosphere. Only including slow GWs in the SD‐WACCMX parameterization could potentially lead to the underestimation of the meridional wind in the model. Analysis also indicates the lower‐thermospheric meridional circulation is stronger in the summer hemisphere, which is attributed to the hemispheric asymmetry in the resolved wave momentum forcing. This study underlines the importance of the whole atmosphere coupling through wave propagation and dissipation. This understanding can guide the model development with an accurate representation of underlying physical processes in the mesosphere and lower thermosphere which drives the lower‐thermospheric circulation as well as the overall dynamics of this region.

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“…Besides electrodynamics effects, the mid‐ and low‐latitude ionosphere electron densities change in response to storm‐time neutral dynamics and composition variations. The storm‐time equatorward neutral wind surge raises the ionosphere to higher altitudes with a slower chemical loss rate, producing positive ionospheric storm effects that strengthen the EIA crests at low latitudes and contribute to the uplift and formation of SED at midlatitudes (e.g., Anderson, 1976; Balan et al., 2010; Datta‐Barua et al., 2011; Lu et al., 2008; W. Wang et al., 2021). In addition, the magnetic meridional/trans‐equatorial neutral winds act to increase the field line‐integrated conductivity so that the equatorial Rayleigh‐Taylor growth rate and EPBs could be somewhat suppressed, though this effect is much weaker than the dominant electrodynamics effect from PRE and storm‐disturbed electric field (Abdu, 2019; Sultan, 1996).…”

Section: Introductionmentioning

confidence: 99%

Significant Mid‐ and Low‐Latitude Ionospheric Disturbances Characterized by Dynamic EIA, EPBs, and SED Variations During the 13–14 March 2022 Geomagnetic Storm

Zhang

Erickson

et al. 2023

JGR Space Physics

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This work investigates mid‐ and low‐latitude ionospheric disturbances over the American sector during a moderate but geo‐effective geomagnetic storm on 13–14 March 2022 (π‐Day storm), using ground‐based Global Navigation Satellite System total electron content data, ionosonde observations, and space‐borne measurements from the Global‐scale Observations of Limb and Disk (GOLD), Swarm, the Defense Meteorological Satellite Program (DMSP), and the Ionospheric Connection Explorer (ICON) satellites. Our results show that this modest but geo‐effective storm created a number of large ionospheric disturbances, especially the dynamic multi‐scale electron density gradient features in the storm main phase as follows: (a) The low‐latitude equatorial ionization anomaly (EIA) exhibited a dramatic storm‐time deformation and reformation, where the EIA crests evolved into a bright equatorial band for 1–2 hr and then quickly separated back into the typical double‐crest structure with a broad crest width and deep equatorial trough. (b) Strong equatorial plasma bubbles (EPBs) occurred with an abnormally high latitude/altitude extension, reaching the geomagnetic latitude of ∼30°, corresponding to an Apex height of 2,600 km above the dip equator. (c) The midlatitude ionosphere experienced a conspicuous storm‐enhanced density (SED) plume structure associated with the subauroral polarization stream (SAPS). This SED/SAPS feature showed an unusual temporal variation that intensified and diminished twice. These distinct mid‐ and low‐latitude ionospheric disturbances could be attributed to the storm‐time electrodynamic effect of electric field perturbation, along with contributions from neutral dynamics and thermospheric composition change.

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Upper Thermospheric Winds

Cited by 14 publications

References 95 publications

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

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

The Lower Thermospheric Winter‐To‐Summer Meridional Circulation: 1. Driving Mechanism

Significant Mid‐ and Low‐Latitude Ionospheric Disturbances Characterized by Dynamic EIA, EPBs, and SED Variations During the 13–14 March 2022 Geomagnetic Storm

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