Estimation of mesoscale thermospheric wind structure using a network of interferometers

Harding, Brian J.; Makela, J. J.; Meriwether, J. W.

doi:10.1002/2015ja021025

Cited by 26 publications

(37 citation statements)

References 34 publications

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“…Both of these conditions can occur as a result of the MTM. At El Leoncito, the observations presented here show that the BW travels South‐West and previous studies have shown that the MTM is known to create or enhance a poleward wind (Harding et al, ; Meriwether et al, ). It is this poleward wind that moves the plasma and creates the BW.…”

Section: Discussionsupporting

confidence: 63%

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All‐Sky Imaging Observations of the Interaction Between the Brightness Wave and ESF Airglow Depletions

Hickey

Martinis

2020

JGR Space Physics

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The midnight temperature maximum (MTM) and equatorial spread F (ESF) are common processes in the low-latitude ionosphere and thermosphere. This work shows the first interaction between the brightness wave (BW), associated with the MTM, and plasma depletions, associated with ESF. Observations from the El Leoncito all-sky imager (ASI) (31.8 • S, 69.3 • W, 19.7 • S magnetic latitude) show concurrent observations of a plasma depletion and a BW. As the BW passes through the depletion, the depletion is modified and becomes an enhancement. Concurrent measurements at the conjugate location show an airglow depletion, indicating that the enhancement is an evolution of the depletion and not a separate feature and that it only occurs in one hemisphere. Previous model results were able to recreate the evolution of an airglow depletion into an enhancement when there is a poleward wind combined with converging zonal winds. We discuss how these wind conditions are often associated with the MTM/BW and can explain this observed enhancement.

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Section: Discussionsupporting

confidence: 63%

“…Regarding the zonal winds, past observations have shown that the MTM can cause a reversal or abatement in the typically eastward zonal wind (Colerico et al, ; Harding et al, ; Meriwether et al, ). This reversal due to the MTM can cause a convergence of the zonal wind in the same way as the common reversal near sunrise.…”

Section: Discussionmentioning

confidence: 99%

All‐Sky Imaging Observations of the Interaction Between the Brightness Wave and ESF Airglow Depletions

Hickey

Martinis

2020

JGR Space Physics

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“…It is described, for example, by Bristow et al () and Nicolls et al () as a means of inverting radar measurements of Doppler shift to derive ion flow vectors. Of more direct relevance here is the work of Harding et al (), who used a regularized inverse approach to estimate the thermospheric neutral wind field from a midlatitude array of narrow‐field Fabry‐Perot instruments.…”

Section: Multistatic Fabry‐perot Wind Fittingmentioning

confidence: 99%

Multiinstrument Studies of Thermospheric Weather Above Alaska

et al. 2018

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We describe how space weather impacts thermospheric winds above Alaska, using an array of ground and space-based instrumentation. Forcing of the thermosphere is observed using coherent (Super Dual Auroral Radar Network) and incoherent (Poker Flat Incoherent Scatter Radar) radars to measure ion convection, plus ground and space-based imagers to map auroral precipitation. The primary emphasis in this work is to determine the neutral thermospheric wind response at F region heights to these drivers, using an array of ground-based all-sky imaging Fabry-Perot spectrometers that record Doppler spectra of optical emissions at 630-nm wavelength, originating from a height of around 240 km. Line-of-sight winds are derived from Doppler shifts and, because each instrument only directly measures this one component, considerable postprocessing must be applied to infer the full three-component vector velocity field. Several techniques for doing so are identified, and a detailed description is presented of the hybrid algorithm used here. Results show that thermospheric winds at these latitudes respond strongly to magnetospheric drivers associated with the aurora over length scales down 100 km or less, and on time scales as short as 15 min. These scales are considerably smaller than those resolved by previous observations, or those captured in semiempirical models such as the Horizontal Wind Model or global-scale first principle models such as the Thermospheric Global Circulation Model and its relatives. Divergence and vorticity commonly occur in the observed horizontal wind fields, over regions spanning hundred of kilometers across and with magnitudes exceeding 0.5 × 10 − 3 s −1 . Plain Language Summary This article combines data from multiple instruments to show howEarth's aurora and flows of ionosphere plasma perturb winds in the neutral atmosphere at 240-km altitude. It shows how atmospheric weather at this height is driven by space weather.

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“…We propose to further investigate ways to reduce the inverse problem's condition number, and its sensitivity to outliers. We note in this context that to deal with fitting radial velocities to multisite FPI observations, Harding et al (2015) successfully regularized the inversion problem in such a way as to produce "smooth" variations in the solved components. It is not clear how well the approach will lend itself to non-ideal observing geometries in the covariance estimation situation, but it nonetheless appears promising, in particular for application to meteor radar estimates of wind covariance.…”

Section: Simulationsmentioning

confidence: 99%

VHF radar measurements of momentum flux using summer polar mesopause echoes

Rüster

Czechowsky

Spargo

2018

Earth Planets Space

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We revisit previously unpublished analysis of observations of the dynamics of the mesopause region over the Norwegian Island of Andøya (69°N, 16°E) made during a 1-week period in summer 1987 during the Middle Atmosphere Cooperation-Summer in Northern Europe (MAC-SINE) campaign using the mobile SOUSY VHF (53.5 MHz) Doppler radar operating in a six-beam mode. We do this in the light of: (1) more recent developments in the measurement of the components of the density-normalized Reynolds stress tensor using meteor radars, and with medium-frequency partial reflection radars using the hybrid Doppler interferometric technique, and (2) satellite measurements of the absolute upward flux of horizontal momentum. We consider of the density-normalized total upward flux of horizontal momentum u ′ w ′ + v ′ w ′ for the 83-90 km height interval. Values of the component of the density-normalized flux for the 6 min to 12.8 h period range, after the tidal components have been removed, and the effects of the aspect sensitivity on the radar beam look directions have been accounted for vary between 5 m 2 s −2 below 86 km and 13 m 2 s −2 above 86 km. The major contribution is from the 6 to 12.8 h period range. The results of the analysis have implications for meteor radar estimates of momentum flux and also for Doppler radar measurements of the same term in the presence of aspect-sensitive scattering.

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Estimation of mesoscale thermospheric wind structure using a network of interferometers

Cited by 26 publications

References 34 publications

All‐Sky Imaging Observations of the Interaction Between the Brightness Wave and ESF Airglow Depletions

All‐Sky Imaging Observations of the Interaction Between the Brightness Wave and ESF Airglow Depletions

Multiinstrument Studies of Thermospheric Weather Above Alaska

VHF radar measurements of momentum flux using summer polar mesopause echoes

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