Small‐scale gravity waves near the mesopause observed by four all‐sky airglow imagers

Ejiri, Mitsumu K.; Shiokawa, K.; Ogawa, T.; Nakamura, Takuji; Maekawa, R.; Tsuda, Toshitaka; Kubota, Minoru

doi:10.1029/2001jd900225

Cited by 16 publications

(15 citation statements)

References 17 publications

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“…Recently, all‐sky airglow imagers make possible visual observations of short wave structures having periods 5–30 min, horizontal wavelengths 10–60 km and phase velocities 10–70 m/s [e.g., Taylor et al , 1995; Nakamura et al , 1999; Ejiri et al , 2001a]. Hodograph analysis of vertical wind profiles obtained with the MU radar at Shigaraki from turbulent induced radio echoes at altitudes 65–85 km [ Nakamura et al , 1993] and from meteor track echoes [ Nakamura et al , 1993; Namboothiri et al , 1996] provides information about IGWs with periods 5–15 hours and horizontal wavelengths 500–3000 km.…”

Section: Discussionmentioning

confidence: 99%

Seasonal variations of medium‐scale gravity wave parameters in the lower thermosphere obtained from spectral airglow temperature imager observations at Shigaraki, Japan

2002

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[1] A method of statistical analysis is used to study parameters of the medium-scale internal gravity waves (IGWs) from the data of the spectral airglow temperature imager (SATI) observations of the OH and O 2 nightglow emissions at Shigaraki, Japan (35°N, 136°E) during April 1998 to May 2001. Average relative magnitudes of spectral components of airglow variations are 1.8-2.4% for the emission rates and 0.5-1% for the rotational temperature in different seasons. Distributions of periods, horizontal wavelengths, and phase speeds have the main maxima at 0.5-2 hours, 100-500 km, and 50-150 m/s, respectively. In winter, the distributions of propagation azimuths are broad with a dominance in the northwest sector and in the southern half of the sky for OH and in the northwest and southeast sectors for O 2 . In spring and summer, IGWs propagate mainly to the northern half of the sky with larger occurrence in the northeast sector for OH emission. Seasonal variations of the average and median IGW magnitudes do not exceed 20-30% and are not stable. In winter, IGWs have maximum occurrence with larger magnitudes, horizontal wavelengths, and phase speeds, particularly at azimuths of 90-210 deg. These results are compared with previous studies.

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Section: Discussionmentioning

confidence: 99%

Seasonal variations of medium‐scale gravity wave parameters in the lower thermosphere obtained from spectral airglow temperature imager observations at Shigaraki, Japan

2002

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“…The other case is that gravity waves may be ducted between the ground and some high regions of the atmosphere in which waves become locally evanescent [ Francis , 1973; Yeh and Liu , 1974; Richmond , 1978; Tuan and Tadic , 1982; Mayr et al , 1984; Wang and Tuan , 1988; Munasinghe et al , 1998]. The wave reflection events were reported from imager and foil chaff measurements [ Schubert et al , 1999; Ejiri et al , 2001; Wüst and Bittner , 2008], even including the reflection of a long‐period gravity wave [ Walterscheid et al , 2000], and the evidence of ducted gravity waves in the mesopause region was revealed by many imager observations [e.g., Taylor et al , 1995; Isler et al , 1997; Walterscheid et al , 1999; Hecht et al , 2001]. Moreover, Hines and Tarasick [1994] and Makhlouf et al [1995, 1998] suggested that an out‐of‐phase relation between airglow brightness and temperature was attributed to the strong wave reflection, which results in the establishment of vertically standing waves.…”

Section: Introductionmentioning

confidence: 99%

Reflection and transmission of atmospheric gravity waves in a stably sheared horizontal wind field

2010

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[1] Applying a second-order fully nonlinear numerical scheme, we have investigated the characteristics of reflection and transmission of atmospheric gravity wave packets in a vertically sheared horizontal wind. When the leading edge of incident wave arrives at the reflecting level predicted by the linear theory, the wave reflection begins to occur. In the reflection process, the reflection and incident waves are superposed with obvious phase staggering, which is different from the wave reflection in a meridionally sheared horizontal wind. In the evanescent region, the wave phase has only weak variation; the wave amplitude decays with the sheared wind growth and vice versa, which is in good agreement with the evanescent wave configuration predicted by the linear theory. Some spectral components of the incident wave can penetrate through the evanescent region and produce a transmitted wave. Both the reflection and transmission coefficients slightly decrease with the moderate increase of the initial amplitude of the incident wave, which is because a large-amplitude wave can induce a strong mean flow; moreover, the waveinduced mean flow plays a more significant role in transferring the energy from the waves to the background flow than in enhancing the transmission of the waves. This is distinguished from the wave reflection in a sheared flow under the wave propagation distance smaller than the density scale height, in which the mean flow induced by a largeramplitude wave significantly strengthens the transmission of the wave. The simulation shows that the reflection loop predicted by the linear theory is not a common phenomenon in the wave reflection. Several groups of simulated cases indicate that the reflection and transmission coefficients depend on not only the amplitude, frequency, and wavenumbers of the incident wave but also the strength and thickness of the evanescent region. The reflection coefficient increases but the transmission coefficient decreases with the relative evanescent thickness growth, and once the strength and thickness of the evanescent region are large enough, the wave hardly penetrates through the sheared wind zone, and the reflection coefficient approaches a constant value, too. Except for the disappearance of the evanescent region, the total sum of the reflection and transmission coefficients of the wave pseudoenergy flux is slightly <1 because of the interaction between the wave and flow. These results suggest that the effects of wave reflection and transmission should be correctly included in the parameterization of gravity waves to attain more realistic middle atmospheric climatology from general circulation models.

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“…Once ω i is known, m is found using the dispersion relation. Another way is to simultaneously observe multiple airglow layers separated in altitude and to correlate the phase structure seen in both layers (assuming the altitude separation is known) [11], [20], [25].…”

Section: Introductionmentioning

confidence: 99%

Experimental Validation of a Technique to Estimate Vertical Wavelength Parameters From Gravity Wave Perturbations on Mesospheric Airglows

Anderson¹,

Makela

Kanwar

2014

IEEE Trans. Geosci. Remote Sensing

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This paper establishes the experimental validation of a new technique to estimate the key intrinsic atmospheric gravity wave (AGW) parameters from imagery of mesospheric airglow layers. The technique provides two independent methods for estimating AGW parameters. In one method, the magnitude of the wave fluctuations is analyzed from image data simultaneously acquired from different locations on the ground to estimate the vertical wavelength. In the other, the phase of the wave is analyzed over time from multiple layers to estimate its vertical wavelength and frequency. After a brief overview of the technique, it is applied to a dataset acquired during the New Mexico Wave Campaign (NMWC) in 2010-2011.

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Small‐scale gravity waves near the mesopause observed by four all‐sky airglow imagers

Cited by 16 publications

References 17 publications

Seasonal variations of medium‐scale gravity wave parameters in the lower thermosphere obtained from spectral airglow temperature imager observations at Shigaraki, Japan

Seasonal variations of medium‐scale gravity wave parameters in the lower thermosphere obtained from spectral airglow temperature imager observations at Shigaraki, Japan

Reflection and transmission of atmospheric gravity waves in a stably sheared horizontal wind field

Experimental Validation of a Technique to Estimate Vertical Wavelength Parameters From Gravity Wave Perturbations on Mesospheric Airglows

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