An investigation of intrinsic gravity wave signatures using coordinated lidar and nightglow image measurements

Taylor, Michael J.; Gu, Yonggen; Tao, Xin; Gardner, Chester S.; Bishop, M. B.

doi:10.1029/95gl02949

Cited by 55 publications

(29 citation statements)

References 6 publications

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“…Because of destructive interference within the layer for smaller-scale motions, the FWHM of an emission layer sets an approximate lower limit to the vertical wavelengths of the motions that can be detected. Similarly, the horizontal field of view sets an upper limit of ---250 km on the horizontal wavelengths to which the imaging technique is sensitive [Taylor et al, 1995c]. (Larger-scale waves have been detected using a time series of image measurements, but their two-dimensional morphology is not easily determined.)…”

Section: Imaging Gravity Wavesmentioning

confidence: 99%

Observational evidence of wave ducting and evanescence in the mesosphere

Isler¹,

Taylor²,

Fritts³

1997

J. Geophys. Res.

129

142

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These results suggest that ducted waves are relatively common in the upper mesosphere and lower thermosphere region, at least over the mid-Pacific Ocean. As small-scale waves which are ducted have the potential to travel much longer horizontal distances than freely propagating waves, the frequency of their occurrence should be taken into account in efforts to quantify gravity wave effects at these altitudes.

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Section: Imaging Gravity Wavesmentioning

confidence: 99%

Observational evidence of wave ducting and evanescence in the mesosphere

Isler¹,

Taylor²,

Fritts³

1997

J. Geophys. Res.

129

142

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show abstract

“…These are smallscale waves seen in the airglow layers between 80 and 105 km and which have observed horizontal phase speeds much less than 100 m/s and periods typically less than a few tens of minutes [e.g., Taylor et al, 1995aTaylor et al, , 1995bWu and Killeen, 1996; periods of typically between 5 and 20 min. When freely propagating and not ducted or trapped, these waves would be expected to travel only a few hundred kilometers from their source in the troposphere to where they are observed near the mesopause in airglow observations.…”

Section: Introductionmentioning

confidence: 99%

Climatology and modeling of quasi‐monochromatic atmospheric gravity waves observed over Urbana Illinois

Hecht¹,

Walterscheid²,

Hickey³

et al. 2001

J. Geophys. Res.

101

165

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Abstract. From analyzing nine months of airglow imaging observations of atmospheric gravity waves (AGWs) over Adelaide, Australia (35øS) [Walterscheid et al., 1999] have proposed that many of the quasi-monochromatic waves seen in the images were primarily thermally ducted. Here are presented 15 months of observations, from February 1996 to May 1997, for AGW frequency and propagation direction from a northern latitude site, Urbana Illinois (40øN). As Adelaide, Urbana is geographically distant from large orographic features. Similar to what was found in Adelaide, the AGWs seem to originate from a preferred location during the time period around summer solstice. In conjunction with these airglow data there exists MF radar data to provide winds in the 90 km region and near-simultaneous lidar data which provide a temperature climatology. The temperature data have previously been analyzed by States and Gardner [2000]. The temperature and wind data are used here in a full wave model analysis to determine the characteristics of the wave ducting and wave reflection during the 15 month observation period. This model analysis is applied to this and another existing data set recently described by Nakamura et al. [1999]. It is shown that the existence of a thermal duct around summer solstice can plausibly account for our observations. However, the characteristics of the thermal duct and the ability of waves to be ducted is also greatly dependent on the characteristics of the background wind. A simple model is constructed to simulate the trapping of these waves by such a duct. It is suggested that the waves seen over Urbana originate no more than a few thousand kilometers from the observation site. IntroductionThe ducting or trapping of atmospheric gravity waves (AGWs) has long been a subject of interest [e.g., Pitteway and

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“…Lidar measurements of Na atom concentration over low latitude stations have been carried out for several decades (e.g. Clemesha et al 1979;Taylor et al 1995;Collins et al 2002;Clemesha 2004;Sarkhel et al 2009Sarkhel et al , 2010Sarkhel et al , 2012a. On occasion, the Na concentration profiles show enhancement by a factor of 2 or more over the usual background layer in a narrow altitude region of up to a few kilometer thickness.…”

Section: Introductionmentioning

confidence: 99%

A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India

et al. 2015

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The height-time-concentration map of neutral sodium (Na) atoms measured by a Na lidar during the night of 18 to 19 March 2007 over Gadanki, India (13.5°N, 79.2°E) reveals an unusual structure in the Na layer for around 30 min in the altitude range of 92 to 98 km which is similar to the usual 'C' type structures observed at other locations. In order to understand the physical mechanism behind the generation of this unusual event, an investigation is carried out combining the data from multiple instruments that include the meteor wind radar over Thiruvananthapuram, India (8.5°N, 77°E) and the SABER instrument onboard the TIMED satellite. The temperature and wind profiles from the data set provided by these instruments allow us to infer the Richardson number which is found to be noticeably less than the canonical threshold of 0.25 above 92 km over Thiruvananthapuram suggesting the plausible generation of Kelvin-Helmholtz (KH) billows over southwestern part of the Indian subcontinent. Based on the average wind speed and direction over Thiruvananthapuram, it is proposed that the KH-billow structure was modified due to the background wind and was advected with it in nearly 'frozen-in' condition (without significant decay) in the northeastward direction reaching the Na lidar location (Gadanki). This case study, therefore, presents a scenario wherein the initially deformed KH-billow structure survived for a few hours (instead of a few minutes or tens of minutes as reported in earlier works) in an apparently 'frozen-in' condition under favorable background conditions. In this communication, we suggest a hypothesis where this deformed KH-billow structure plays crucial role in creating the abovementioned unusual structure observed in the Na layer over Gadanki.

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An investigation of intrinsic gravity wave signatures using coordinated lidar and nightglow image measurements

Cited by 55 publications

References 6 publications

Observational evidence of wave ducting and evanescence in the mesosphere

Observational evidence of wave ducting and evanescence in the mesosphere

Climatology and modeling of quasi‐monochromatic atmospheric gravity waves observed over Urbana Illinois

A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India

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