Extraction of motion parameters of gravity-wave structures from all-sky OH image sequences

Haque, Rezaul; Swenson, G. R.

doi:10.1364/ao.38.004433

Cited by 15 publications

(11 citation statements)

References 20 publications

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“…Then, the subtracted image counts I s were normalized by the average of the whole median image counts I m , that is, I s /I m . Finally, we created a time-difference (TD) image by taking the differences between two sequential images (Swenson and Mende, 1994;Haque and Swenson, 1999). The Milky Way structures move more slowly than the smallscale gravity wave in the sequential images.…”

Section: Image Correctionsmentioning

confidence: 99%

Gravity wave momentum flux in the upper mesosphere derived from OH airglow imaging measurements

et al. 2007

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We report procedures to identify small-scale (20-100 km) atmospheric gravity waves from OH airglow images to estimate momentum fluxes carried by the waves. We also deduce contamination of background continuum emission in OH image, by comparing a simultaneous observation of OH lines measured by the Spectral Airglow Temperature Imager (SATI). We applied the procedures to a one-night dataset obtained at Shigaraki, Japan (34.9• N, 136.1 • E) on November 19, 1999. The background wind, which is essential for deriving the intrinsic parameters of gravity waves, was measured by the Middle and Upper Atmosphere (MU) radar. Contamination of background continuum emission with the OH filter was deduced to be 30%. From these procedures, we found that the gravity waves identified in the OH images were mainly propagating southward or southeastward with horizontal wavelengths of 60-90 km and apparent phase speeds of 40-80 m/s. The estimated momentum fluxes on this night was 1-15 m 2 s −2 , with an average of 4.9 m 2 s −2 .

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Section: Image Correctionsmentioning

confidence: 99%

Gravity wave momentum flux in the upper mesosphere derived from OH airglow imaging measurements

et al. 2007

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“…In the absence of moonlight the airglow in the SWIR band is the brightest source. Previous work by other researchers using CCD cameras has examined seasonal variations of gravity waves [4,5,6] and the extraction of gravity wave motion parameters [5,6,7,8]. However, CCD cameras are insensitive to wavelengths greater than 1 μm wherein lies most of the airglow energy.…”

Section: I0 Introductionmentioning

confidence: 99%

“…Also, the use of a fisheye lens to image the whole sky onto a single CCD limits resolution, e.g. 0.36 deg/pixel [7] and wave motion can be smeared by exposure times ranging from 15 sec [6] to 120 sec [5].…”

Section: I0 Introductionmentioning

confidence: 99%

Seasonal hemispherical SWIR airglow imaging

et al. 2011

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Airglow luminescence in the SWIR region due to upper atmospheric recombination of solar excited molecules is a well accepted phenomenon. While the intensity appears broadly uniform over the whole sky hemisphere, we are interested in variations in four areas: 1) fine periodic features known as gravity waves, 2) broad patterns across the whole sky, 3) temporal variations in the hemispheric mean irradiance over the course of the night, and 4) long term seasonal variations in the mean irradiance. An experiment is described and results presented covering a full year of high resolution hemispheric SWIR irradiance images. An automated gimbal views 45 hemispheric positions, using 30 second durations, and repeats approximately every half hour through out the night. The gimbal holds co-mounted and bore-sighted visible and SWIR cameras. Measuring airglow with respect to spatial, temporal, and seasonal variations will facilitate understanding its behavior and possible benefits, such as night vision and predicting upper atmosphere turbulence. The measurements were performed in a tropical marine location on the island of Kauai Hi.

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“…In the absence of moonlight the airglow in the SWIR band is the brightest source. Previous work using CCD cameras has examined seasonal variations of gravity waves [5,6,7] and the extraction of gravity wave motion parameters [6,7,8,9]. However, CCD cameras are insensitive to wavelengths greater than 1 μm wherein lies most of the airglow energy.…”

Section: I0 Introductionmentioning

confidence: 99%

Spatial and temporal variability of SWIR air glow measurements

et al. 2011

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It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band between 0.9 and 1.7 μm wave length. This phenomenon, often referred to as airglow, has been demonstrated as an effective illumination source for passive low light level night time imaging applications. It addition it has been shown that observation of the spatial and temporal variations of the illumination can be used to characterize atmospheric tidal wave actions in the airglow region. These spatio-temporal variations manifest themselves as traveling wave patterns whose period and velocity are related to the wind velocity at 85 km as well as the turbulence induced by atmospheric vertical instabilities. In this paper we present nearly a year of airglow observations over the whole sky, showing long term and short term fluctuations to characterize SWIR night time image system performance.

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Extraction of motion parameters of gravity-wave structures from all-sky OH image sequences

Cited by 15 publications

References 20 publications

Gravity wave momentum flux in the upper mesosphere derived from OH airglow imaging measurements

Gravity wave momentum flux in the upper mesosphere derived from OH airglow imaging measurements

Seasonal hemispherical SWIR airglow imaging

Spatial and temporal variability of SWIR air glow measurements

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