Observed nocturnal gravity wave variances and zonal momentum flux in mid-latitude mesopause region over Fort Collins, Colorado, USA

Acott, P.; She, C. Y.; Krueger, David A.; Yan, Zhaoai; Yuan, Tao; Yue, Jia; Harrell, Sean

doi:10.1016/j.jastp.2010.10.016

Cited by 15 publications

(20 citation statements)

References 34 publications

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“…Several methods are available to infer GW‐induced temperature perturbations diagnostically from observed GW‐induced sodium density perturbations. Sodium density perturbations have previously been used to calculate temperature perturbations associated with GWs (Bossert et al, ; Shelton et al, ; Swenson & Gardner, ), and sodium lidars have also been previously used to calculate MFs associated with GWs (Acott et al, ; Gardner & Liu, ). Assuming hydrostatic GWs and purely vertical and linear gradients in background temperatures and sodium densities, GW‐induced perturbations in temperature can be derived from sodium density perturbations using parcel‐advection methods (see Eckermann et al, ).…”

Section: Temperature and Mf Measurements And Validationmentioning

confidence: 99%

Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

et al. 2018

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During the Deep Propagating Gravity Wave Experiment (DEEPWAVE) 13 July 2014 research flight over the South Island of New Zealand, a multiscale spectrum of mountain waves (MWs) was observed. High‐resolution measurements of sodium densities were available from ~70 to 100 km for the duration of this flight. A comprehensive technique is presented for obtaining temperature perturbations, T′, from sodium mixing ratios over a range of altitudes, and these T′ were used to calculate the momentum flux (MF) spectra with respect to horizontal wavelengths, λH, for each flight segment. Spectral analysis revealed MWs with spectral power centered at λH of ~80, 120, and 220 km. The temperature amplitudes of these MWs varied between the four cross‐mountain flight legs occurring between 6:10UT and 9:10UT. The average spectral T′ amplitudes near 80 km in altitude ranged from 7–13 K for the 220 km λH MW and 4–8 K for the smaller λH MWs. These amplitudes decayed significantly up to 90 km, where a critical level for MWs was present. The average MF per unit mass near 80 km in altitude ranged from ~13 to 60 m2/s2 across the varying spectra over the duration of the research flight and decayed to ~0 by 88 km in altitude. These MFs are large compared to zonal means and highlight the importance of MWs in the momentum budget of the mesosphere and lower thermosphere at times when they reach these altitudes.

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Section: Temperature and Mf Measurements And Validationmentioning

confidence: 99%

Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

et al. 2018

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“…The gravity wave momentum flux (MF) and its divergence can provide insight into the wave's amplitude and impacts in the mesopause region. In addition to the coplanar lidar beam measurement [Acott et al, 2011], as discussed by Ern et al [2004] and Alexander et al [2008], the relation between absolute MF and temperature variance is…”

Section: Figures 4a and 4bmentioning

confidence: 99%

Evidence of dispersion and refraction of a spectrally broad gravity wave packet in the mesopause region observed by the Na lidar and Mesospheric Temperature Mapper above Logan, Utah

et al. 2016

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Gravity wave packets excited by a source of finite duration and size possess a broad frequency and wave number spectrum and thus span a range of temporal and spatial scales. Observing at a single location relatively close to the source, the wave components with higher frequency and larger vertical wavelength dominate at earlier times and at higher altitudes, while the lower frequency components, with shorter vertical wavelength, dominate during the latter part of the propagation. Utilizing observations from the Na lidar at Utah State University and the nearby Mesospheric Temperature Mapper at Bear Lake Observatory (41.9°N, 111.4°W), we investigate a unique case of vertical dispersion for a spectrally broad gravity wave packet in the mesopause region over Logan, Utah (41.7°N, 111.8°W), that occurred on 2 September 2011, to study the waves' evolution as it propagates upward. The lidar-observed temperature perturbation was dominated by close to a 1 h modulation at 100 km during the early hours but gradually evolved into a 1.5 h modulation during the second half of the night. The vertical wavelength also decreased simultaneously, while the vertical group and phase velocities of the packet apparently slowed, as it was approaching a critical level during the second half of the night. A two-dimensional numerical model is used to simulate the observed gravity wave processes, finding that the location of the lidar relative to the source can strongly influence which portion of the spectrum can be observed at a particular location relative to a source.

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“…For example, the airglow measurement techniques like OH imaging [ Swenson and Mende , ] can provide important horizontal wave structures information at high temporal resolution and capture the direct evidence of GW breaking and instability features like ripples, but it lacks vertical coverage of some key parameters, such as temperature and horizontal wind gradients, preventing a comprehensive investigation on this subject. On the other hand, lidar and radar, especially narrowband sodium lidar [ Franke and Collins , ; Li et al ., ], are able to measure the temperature and wind vertical profiles, even the GW‐induced horizontal momentum flux [ Acott et al ., ], simultaneously with high resolution, and allow people to surgically carry out statistical studies on instability [ Zhao et al ., ; Li et al ., ]. However, without critical horizontal information about the GWs, such as horizontal phase speed and wavelength, it is also difficult to reveal the full spectrum of the wave breaking and the instability involved.…”

Section: Introductionmentioning

confidence: 99%

“…The wave breaking process deposits momentum into the mean flow field, causing mean flow acceleration in the wave propagation direction; changes the thermal structure; and generates turbulence around the breaking region. and radar, especially narrowband sodium lidar [Franke and Collins, 2003;Li et al, 2007a], are able to measure the temperature and wind vertical profiles, even the GW-induced horizontal momentum flux [Acott et al, 2011], simultaneously with high resolution, and allow people to surgically carry out statistical studies on instability [Zhao et al, 2003;Li et al, 2005a]. However, without critical horizontal information about the GWs, such as horizontal phase speed and wavelength, it is also difficult to reveal the full spectrum of the wave breaking and the instability involved.…”

Section: Introductionmentioning

confidence: 99%

A coordinated investigation of the gravity wave breaking and the associated dynamical instability by a Na lidar and an Advanced Mesosphere Temperature Mapper over Logan, UT (41.7°N, 111.8°W)

et al. 2014

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The impacts of gravity wave (GW) on the thermal and dynamic characteristics within the mesosphere/lower thermosphere, especially on the atmospheric instabilities, are still not fully understood. In this paper, we conduct a comprehensive and detailed investigation on one GW breaking event during a collaborative campaign between the Utah State University Na lidar and the Advanced Mesospheric Temperature Mapper (AMTM) on 9 September 2012. The AMTM provides direct evidence of the GW breaking as well as the horizontal parameters of the GWs involved, while the Na lidar's full diurnal cycle observations are utilized to uncover the roles of tide and GWs in generating a dynamical instability layer. By studying the changes of the OH layer peak altitude, we located the wave breaking altitude as well as the significance of a 2 h wave that are essential to this instability formation. By reconstructing the mean fields, tidal and GW variations during the wave breaking event, we find that the large-amplitude GWs significantly changed the Brunt-Vaisala frequency square and the horizontal wind shear when superimposed on the tidal wind, producing a transient dynamic unstable region between 84 km and 87 km around 11:00 UT that caused a subsequent small-scale GW breaking. IntroductionThe gravity wave (GW) forcing and its related spectra within the mesosphere/lower thermosphere (MLT) are the key parameters for the understanding of energy and momentum transfers between the lower and middle atmosphere and the ionosphere. They have been known to drive the circulation and generate the counter intuitive cold summer and warm winter in the mesopause region [Garcia and Solomon, 1985], along with some irregularities in the ionosphere [Liu and Vadas, 2013]. Yet after decades of investigations, their characteristics and effects on the upper atmosphere are still not fully understood due to the GW's random spatial scales with their periods varying from a few minutes to several hours. Mainly generated in the troposphere by orographic, convection, and jet-front system, the GWs propagate upward with growing amplitude to compensate for the decrease of the air density due to conservation of the wave energy density during their propagation, before they reach the critical levels or become unstable and break . It is also possible that the GW breaking can generate secondary waves within the breaking region [Vadas et al., 2003;Smith et al., 2013], affecting the atmosphere above MLT region. The wave breaking process deposits momentum into the mean flow field, causing mean flow acceleration in the wave propagation direction; changes the thermal structure; and generates turbulence around the breaking region.Ground-based experimental studies have been playing the significant role in studying the GW dynamics and the associated atmospheric instabilities during the recent decades. However, single instrument only partially resolves the complex wave breaking process and the instability phenomenon. For example, the airglow measurement techniques like OH ima...

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Observed nocturnal gravity wave variances and zonal momentum flux in mid-latitude mesopause region over Fort Collins, Colorado, USA

Cited by 15 publications

References 34 publications

Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

Evidence of dispersion and refraction of a spectrally broad gravity wave packet in the mesopause region observed by the Na lidar and Mesospheric Temperature Mapper above Logan, Utah

A coordinated investigation of the gravity wave breaking and the associated dynamical instability by a Na lidar and an Advanced Mesosphere Temperature Mapper over Logan, UT (41.7°N, 111.8°W)

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