Observation of Quasiperiodic Structures in the Hydroxyl Airglow on Scales Below 100 m

Franzen, Christoph; Espy, P. J.; Hibbins, R. E.; Djupvik, A. A.

doi:10.1029/2018jd028732

Cited by 4 publications

(10 citation statements)

References 35 publications

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“…In this manner, the Einstein coefficients of the Q-branch lines can be calculated relative to those in the P-branch that do not suffer from L-uncoupling [2]. For transitions, where the P-branch is not observed, for example, the (6,4) transition, the R-branch can be used.…”

Section: Direct Line Ratio Methodsmentioning

confidence: 99%

“…French et al [15] showed that the Einstein coefficients from the (6,2) Meinel transition with ∆J = 0 (Q-branch) become significantly lower with increasing rotational level than three different published sets of values. This discrepancy would affect the atmospheric temperatures fitted to either the Q-branch or a combination of the P-, Q-, and R-branches, depending upon their relative weighting.…”

Section: Introductionmentioning

confidence: 91%

“…Most frequently the filters J, H, and K are used to isolate the wavelength regions 1.165-1.328 µm, 1.484-1.780 µm, and 2.083-2.363 µm, respectively. The J-band filter spans two OH Meinel transitions, the (7,4) and (8,5), while the H-band filter contains the (3,1), (4,2), (5,3) and (6,4) transitions and the K-band filter spans the (9,7) transition.…”

Section: Instrumentation and Data Setmentioning

confidence: 99%

“…Pendleton and Taylor showed that this effect accounted for the discrepancy found by French et al [15] for the (6,2) Q-branch line strengths. However, while this angular-momentum uncoupling was verified for the (6,2) band, it has not been tested experimentally for transitions from other vibrational levels. Due to the exothermicity of reaction (1), the internal rotational energy, primarily at high rotational levels N > 3, of the OH molecule may not be completely thermalized with the surrounding gas as has been indicated by recent observations [18].…”

Section: Introductionmentioning

confidence: 99%

“…Radiative relaxation of this excited OH in the Meinel system results in the bright near-infrared (NIR) radiation known as OH nightglow or airglow. The OH Meinel emission occurs over an approximately 8 km thick layer [1], and spectroscopic observations of the nightglow have been used to infer the atmospheric conditions at the peak of the layer near 87 km altitude [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Airglow Derived Measurements of Q-Branch Transition Probabilities for Several Hydroxyl Meinel Bands

et al. 2019

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Spectroscopic measurements of the hydroxyl (OH) airglow emissions are often used to infer neutral temperatures near the mesopause. Correct Einstein coefficients for the various transitions in the OH airglow are needed to calculate accurate temperatures. However, studies from some studys showed experimentally and theoretically that the most commonly used Einstein spontaneous emission transition probabilities for the Q-branch of the OH Meinel (6,2) transition are overestimated. Extending their work to several Δv = 2 and 3 transitions from v′ = 3 to 9, we have determined Einstein coefficients for the first four Q-branch rotational lines. These have been derived from high resolution, high signal to noise spectroscopic observations of the OH airglow in the night sky from the Nordic Optical Telescope. The Q-branch Einstein coefficients calculated from these spectra show that values currently tabulated in the HITRAN database overestimate many of the Q-branch transition probabilities. The implications for atmospheric temperatures derived from OH Q-branch measurements are discussed.

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Section: Direct Line Ratio Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Instrumentation and Data Setmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Airglow Derived Measurements of Q-Branch Transition Probabilities for Several Hydroxyl Meinel Bands

et al. 2019

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Horizontal sodium density variations for laser guide star tip-tilt measurements

Holdorf,

Martínez-Rey

2024

Monthly Notices of the Royal Astronomical Society

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Adaptive optics, particularly with laser guide stars, has revolutionized ground-based astronomy. However, one known limitation is the requirement of a natural guide star to retrieve tip-tilt information. This is the limiting factor in the overall achievable sky coverage with adaptive optics systems as natural guide stars are not available for all science targets. There have been numerous different techniques proposed to overcome this limitation, however many are restricted by current technology. This work investigates the use of density perturbations in the sodium layer to retrieve the tip-tilt information. In this work, we identify atmospheric gravity waves as a mechanism that could cause perturbations in the sodium layer density. Archival hydroxyl airglow data was analysed to assess whether the density perturbations caused by atmospheric gravity waves are on the correct scales and have enough contrast to be used for laser guide star tip-tilt retrieval. This data showed a median contrast of 1.9% for a laser guide star with a full-width half max of 25″. Then to determine if these perturbations would be visible with a laser guide star at a high enough signal-to-noise ratio the Mathematica package LGSBloch was utilised. The CaNaPy laser guide star R&D facility was chosen to model as it has a state-of-the-art 70 W sodium laser. Promising results were found when modelling this method with the CaNaPy facility as a framework. This demonstrates that if these same perturbations were present in the sodium layer, sodium density variations are a potential mechanism to retrieve tip-tilt using laser guide stars.

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Hydroxyl airglow observations for investigating atmospheric dynamics: results and challenges

et al. 2023

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Abstract. Measurements of hydroxyl (OH*) airglow intensity are a straightforward and cost-efficient method which allows the derivation of information about the climate and dynamics of the upper mesosphere/lower thermosphere (UMLT) on different spatiotemporal scales during darkness. Today, instrument components can be bought “off-the-shelf” and developments in detector technology allows operation without cooling, or at least without liquid nitrogen cooling, which is difficult to automate. This makes instruments compact and suitable for automated operation. Here, we briefly summarize why an OH* airglow layer exists, how atmospheric dynamics influence it and how temperature can be derived from OH* airglow measurements. Then, we provide an overview of the scientific results regarding atmospheric dynamics (mainly gravity waves (GWs) but also planetary waves (PWs) and infrasound) achieved with OH* airglow measurements. We focus on long-term ground-based OH* airglow measurements or airglow measurements using a network of ground-based instruments. The paper includes further results from global or near-global satellite-based OH* airglow measurements, which are of special importance for characterizing the OH* airglow layer. Additionally, the results from the very few available airborne case studies using OH* airglow instruments are summarized. Scientific and technical challenges for the next few years are described.

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Observation of Quasiperiodic Structures in the Hydroxyl Airglow on Scales Below 100 m

Cited by 4 publications

References 35 publications

Airglow Derived Measurements of Q-Branch Transition Probabilities for Several Hydroxyl Meinel Bands

Airglow Derived Measurements of Q-Branch Transition Probabilities for Several Hydroxyl Meinel Bands

Horizontal sodium density variations for laser guide star tip-tilt measurements

Hydroxyl airglow observations for investigating atmospheric dynamics: results and challenges

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