The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Application to measurements over Alaska

Nicolls, M. J.; Vadas, Sharon L.; Meriwether, J. W.; Conde, M.; Hampton, Donald

doi:10.1029/2012ja017542

Cited by 30 publications

(47 citation statements)

References 77 publications

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“…Since we are only analyzing the published figures (not the data), we do not include error bars here. However, it is straightforward to include them [ Nicolls et al , 2012].…”

Section: Determination Of λH λZ and ωIr From In‐situ Satellite Obsementioning

confidence: 99%

“…Our second (more substantial) “test” is contained in our companion paper. Recently, high‐resolution, 3D neutral wind and temperature measurements using Fabry Perot observatories in Alaska have determined the phase shifts and amplitude ratios of a monochromatic GW observed there on 9–10 January 2010 [ Nicolls et al , 2012]. Using forward modeling, λ H and the direction of propagation were determined.…”

Section: Introductionmentioning

confidence: 99%

“…Section 5 contains our conclusions. A companion paper compares the predictions of this theory with Fabry‐Perot observations of a monochromatic GW observed in the thermosphere above Alaska on 9–10 January 2010 [ Nicolls et al , 2012].…”

Section: Introductionmentioning

confidence: 99%

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The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Theory

Vadas

Nicolls

2012

J. Geophys. Res.

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[1] We derive the high-frequency, compressible, dissipative dispersion and polarization relations for linear acoustic-gravity waves (GWs) and acoustic waves (AWs) in a single-species thermosphere. The wave amplitudes depend explicitly on time, consistent with a wave packet approach. We investigate the phase shifts and amplitude ratios between the GW components, which include the horizontal (u H ′ ) and vertical (w′) velocity, density (r′), pressure (p′), and temperature (T ′) perturbations. We show how GWs with large vertical wavelengths l z have dramatically different phase and amplitude relations than those with small l z . For zero viscosity, as jl z j increases, the phase between u H ′ and w′ decreases from 0 to $À90 , the phase between u H ′ and T′ decreases from $90 to 0 , and the phase between T ′ and r′ decreases from $180 to 0 for l H ≫ jl z j, where l H is the horizontal wavelength. This effect lessens substantially with increasing altitudes, primarily because the density scale height H increases. We show how in-situ satellite measurements of either (1) the 3D neutral wind or (2) r′, T′, w′, and the cross-track wind, can be used to infer a GW's l H , l z , propagation direction, and intrinsic frequency w Ir . We apply this theory to a GW observed by the DE2 satellite. We find a significant region of overlap in parameter space for 5 independent constraints (i.e., T′ 0 /r′ 0 , the phase shift between T ′ and w′, and the distance between wave crests), which provides a good test and validation of this theory. In a companion paper, we apply this theory to ground-based observations of a GW over Alaska.Citation: Vadas, S. L., and M. J. Nicolls (2012), The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Theory,

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“…Since we are only analyzing the published figures (not the data), we do not include error bars here. However, it is straightforward to include them [ Nicolls et al , 2012].…”

Section: Determination Of λH λZ and ωIr From In‐situ Satellite Obsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Theory

Vadas

Nicolls

2012

J. Geophys. Res.

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“…For typical horizontal scale sizes of the horizontal flow, and on time scales of hours, the magnitude of the vertical wind is not expected to be more than a few m/s [ Rishbeth et al , ; Smith , ]. However, measurements of persistent large vertical wind are not uncommon, especially at high latitudes [ Larsen and Meriwether , ; Nicolls et al , ]. Spencer et al [] first observed large, 80 m/s vertical winds at the AE‐C satellite, and ground‐based instruments have measured vertical winds at auroral latitudes of a few tens of m/s [ Rees et al , ; Ishii et al , ; Smith , ; Nicolls et al , ; Anderson et al , ; Larsen and Meriwether , , and references therein].…”

Section: Introductionmentioning

confidence: 99%

Storm time response of the midlatitude thermosphere: Observations from a network of Fabry‐Perot interferometers

et al. 2014

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Observations of thermospheric neutral winds and temperatures obtained during a geomagnetic storm on 2 October 2013 from a network of six Fabry‐Perot interferometers (FPIs) deployed in the Midwest United States are presented. Coincident with the commencement of the storm, the apparent horizontal wind is observed to surge westward and southward (toward the equator). Simultaneous to this surge in the apparent horizontal winds, an apparent downward wind of approximately 100 m/s lasting for 6 h is observed. The apparent neutral temperature is observed to increase by approximately 400 K over all of the sites. Observations from an all‐sky imaging system operated at the Millstone Hill observatory indicate the presence of a stable auroral red (SAR) arc and diffuse red aurora during this time. We suggest that the large sustained apparent downward winds arise from contamination of the spectral profile of the nominal thermospheric 630.0 nm emission by 630.0 nm emission from a different (nonthermospheric) source. Modeling demonstrates that the effect of an additional population of 630.0 nm photons, with a distinct velocity and temperature distribution, introduces an apparent Doppler shift when the combined emissions from the two sources are analyzed as a single population. Thus, the apparent Doppler shifts should not be interpreted as the bulk motion of the thermosphere, calling into question results from previous FPI studies of midlatitude storm time thermospheric winds. One possible source of contamination could be fast O related to the infusion of low‐energy O+ ions from the magnetosphere. The presence of low‐energy O+ is supported by observations made by the Helium, Oxygen, Proton, and Electron spectrometer instruments on the twin Van Allen Probes spacecraft, which show an influx of low‐energy ions during this period. These results emphasize the importance of distributed networks of instruments in understanding the complex dynamics that occur in the upper atmosphere during disturbed conditions.

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“…Only GWs with large λ z can propagate deep into the thermosphere ). Eventually, every GW dissipates in the thermosphere (Pitteway and Hines, 1963;Hines, 1973;Richmond, 1978;Hickey and Cole, 1988;Zhang and Yi, 2002;VF05;Walterscheid and Hickey, 2011;Vadas and Nicolls, 2012;Nicolls et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere

Liu

Yue

et al. 2013

Ann. Geophys.

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Abstract. We study the momentum deposition in the thermosphere from the dissipation of small amplitude gravity waves (GWs) within a wave packet using a fully nonlinear two-dimensional compressible numerical model. The model solves the nonlinear propagation and dissipation of a GW packet from the stratosphere into the thermosphere with realistic molecular viscosity and thermal diffusivity for various Prandtl numbers. The numerical simulations are performed for GW packets with initial vertical wavelengths (λ z ) ranging from 5 to 50 km. We show that λ z decreases in time as a GW packet dissipates in the thermosphere, in agreement with the ray trace results of Vadas and Fritts (2005) (VF05). We also find good agreement for the peak height of the momentum flux (z diss ) between our simulations and VF05 for GWs with initial λ z ≤ 2πH in an isothermal, windless background, where H is the density scale height. We also confirm that z diss increases with increasing Prandtl number. We include eddy diffusion in the model, and find that the momentum deposition occurs at lower altitudes and has two separate peaks for GW packets with small initial λ z . We also simulate GW packets in a non-isothermal atmosphere. The net λ z profile is a competition between its decrease from viscosity and its increase from the increasing background temperature. We find that the wave packet disperses more in the non-isothermal atmosphere, and causes changes to the momentum flux and λ z spectra at both early and late times for GW packets with initial λ z ≥ 10 km. These effects are caused by the increase in T in the thermosphere, and the decrease in T near the mesopause.

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The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Application to measurements over Alaska

Cited by 30 publications

References 77 publications

The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Theory

The phases and amplitudes of gravity waves propagating and dissipating in the thermosphere: Theory

Storm time response of the midlatitude thermosphere: Observations from a network of Fabry‐Perot interferometers

Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere

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