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Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Statistical Characteristics Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao
Statistical Characteristics Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao
Publications
The long-term statistical characteristics of high-frequency quasi-monochromatic gravity waves are presented using multi-year airglow images observed at Andes Lidar Observatory (ALO, 30.3° S, 70.7° W) in northern Chile. The distribution of primary gravity wave parameters including horizontal wavelength, vertical wavelength, intrinsic wave speed, and intrinsic wave period are obtained and are in the ranges of 20–30 km, 15–25 km, 50–100 m s−1, and 5–10 min, respectively. The duration of persistent gravity wave events captured by the imager approximately follows an exponential distribution with an average duration of 7–9 min. The waves tend to propagate against the local background winds and …
The Geocoronal H Α Cascade Component Determined From Geocoronal H Β Intensity Measurements, F. L. Roesler, E. J. Mierkiewicz, S. M. Nossal
The Geocoronal H Α Cascade Component Determined From Geocoronal H Β Intensity Measurements, F. L. Roesler, E. J. Mierkiewicz, S. M. Nossal
Publications
"Geocoronal H α and H β intensity measurements using the Wisconsin H α Mapper Fabry-Perot are used to determine the intensity of the H α cascade component. From basic atomic physics and the work of Meier (1995), we show that the total cascade in geocoronal H α emission is 0.52 ± 0.03 times the geocoronal H β intensity, I(H β), for solar Lyman series excitation of geocoronal hydrogen. The results are consistent with the H α cascade measurements of Mierkiewicz et al. (2012), which were determined directly from the analysis of H α line profile measurements, and significantly narrow the …
Numerical And Statistical Evidence For Long-Range Ducted Gravity Wave Propagation Over Halley, Antarctica, J. B. Snively, K. Nielsen, M. P. Hickey, C. J. Heale, M. J. Taylor, T. Moffat-Griffin
Numerical And Statistical Evidence For Long-Range Ducted Gravity Wave Propagation Over Halley, Antarctica, J. B. Snively, K. Nielsen, M. P. Hickey, C. J. Heale, M. J. Taylor, T. Moffat-Griffin
Publications
Abundant short-period, small-scale gravity waves have been identified in the mesosphere and lower thermosphere over Halley, Antarctica, via ground-based airglow image data. Although many are observed as freely propagating at the heights of the airglow layers, new results under modeled conditions reveal that a significant fraction of these waves may be subject to reflections at altitudes above and below.The waves may at times be trapped within broad thermal ducts, spanning from the tropopause or stratopause to the base of the thermosphere (~140 km), which may facilitate long-range propagation (~1000s of km) under favorable wind conditions.
Mesospheric Hydroxyl Airglow Signatures Of Acoustic And Gravity Waves Generated By Transient Tropospheric Forcing, J. B. Snively
Mesospheric Hydroxyl Airglow Signatures Of Acoustic And Gravity Waves Generated By Transient Tropospheric Forcing, J. B. Snively
Publications
"Numerical model results demonstrate that acoustic waves generated by tropospheric sources may produce cylindrical “concentric ring” signatures in the mesospheric hydroxyl airglow layer. They may arrive as precursors to upward propagating gravity waves, generated simultaneously by the same sources, and produce strong temperature perturbations in the thermosphere above. Transient and short-lived, the acoustic wave airglow intensity and temperature signatures are predicted to be detectable by ground-based airglow imaging systems and may provide new insight into the forcing of the upper atmosphere from below."--From publisher's website.
Observed And Modeled Solar Cycle Variation In Geocoronal Hydrogen Using Nrlmsise-00 Thermosphere Conditions And The Bishop Analytic Exosphere Model, S. M. Nossal, E. J. Mierkiewicz, F. L. Roesler
Observed And Modeled Solar Cycle Variation In Geocoronal Hydrogen Using Nrlmsise-00 Thermosphere Conditions And The Bishop Analytic Exosphere Model, S. M. Nossal, E. J. Mierkiewicz, F. L. Roesler
Publications
High precision observations during Solar Cycle 23 using the Wisconsin H‐alpha Mapper (WHAM) Fabry‐Perot quantify a factor of 1.5 ± 0.15 higher Balmer α column emission intensity during near‐solar‐maximum than during solar minimum conditions. An unresolved question is how does the observed solar cycle variation in the hydrogen column emission compare with that calculated from the hydrogen distribution in atmospheric models? We have compared WHAM solar minimum and near‐solar‐maximum column intensity observations with calculations using the thermospheric hydrogen density profile and background thermospheric conditions from the Mass Spectrometer Incoherent Scatter (NRLMSISE‐00) empirical model extended to exospheric altitudes using the analytic …
Oh And Oi Airglow Layer Modulation By Ducted Short-Period Gravity Waves: Effects Of Trapping Altitude, Jonathan B. Snively, Victor P. Pasko, Michael J. Taylor
Oh And Oi Airglow Layer Modulation By Ducted Short-Period Gravity Waves: Effects Of Trapping Altitude, Jonathan B. Snively, Victor P. Pasko, Michael J. Taylor
Publications
Perturbations to the OH and OI [O(1S) 557.7 nm] airglow layers by ducted gravity waves near the Brunt‐Väisälä period are investigated using a 2‐D numerical model. Airglow signatures of these waves are strongly determined by perturbations of O, O3, and H, which exhibit peak densities near and above mesopause. Strong periodic vertical wind components of short‐period gravity waves induce opposite relative density perturbations above and below the layer density peaks. Airglow signatures for ducted waves depend on the specific vertical shapes and altitudes of the wave packets relative to ambient species density profiles; waves perturbing only the bottoms or tops …
Atmospheric Airglow Fluctuations Due To A Tsunami‐Driven Gravity Wave Disturbance, Michael P. Hickey Ph.D., G. Schubert, R. L. Walterscheid
Atmospheric Airglow Fluctuations Due To A Tsunami‐Driven Gravity Wave Disturbance, Michael P. Hickey Ph.D., G. Schubert, R. L. Walterscheid
Publications
A spectral full‐wave model is used to study the upward propagation of a gravity wave disturbance and its effect on atmospheric nightglow emissions. Gravity waves are generated by a surface displacement that mimics a tsunami having a maximum amplitude of 0.5 m, a characteristic horizontal wavelength of 400 km, and a horizontal phase speed of 200 m/s. The gravity wave disturbance can reach F region altitudes before significant viscous dissipation occurs. The response of the OH Meinel nightglow in the mesopause region (∼87 km altitude) produces relative brightness fluctuations, which are ∼1% of the mean for overhead viewing. The wave …
Analysis And Modeling Of Ducted And Evanescent Gravity Waves Observed In The Hawaiian Airglow, D. B. Simkhada, J. B. Snively, M. J. Taylor, S. J. Franke
Analysis And Modeling Of Ducted And Evanescent Gravity Waves Observed In The Hawaiian Airglow, D. B. Simkhada, J. B. Snively, M. J. Taylor, S. J. Franke
Publications
Short-period gravity waves of especially-small horizontal scale have been observed in the Maui, Hawaii airglow. Typical small-scale gravity wave events have been investigated, and intrinsic wave propagation characteristics have been calculated from simultaneous meteor radar wind measurements. Here we report specific cases where wave structure is significantly determined by the local wind structure, and where wave characteristics are consistent with ducted or evanescent waves throughout the mesopause region. Two of the documented events, exhibiting similar airglow signatures but dramatically different propagation conditions, are selected for simple numerical modeling case studies. First, a Doppler-ducted wave trapped within relatively weak wind flow …
On The Variability Of Mesospheric Oh Emission Profiles, Romina Nikoukar, Gary R. Swenson, Alan Z. Liu, Farzad Kamalabadi
On The Variability Of Mesospheric Oh Emission Profiles, Romina Nikoukar, Gary R. Swenson, Alan Z. Liu, Farzad Kamalabadi
Physical Sciences - Daytona Beach
Mesospheric OH radiance limb profiles measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) spacecraft were inverted to yield altitude profiles of OH volume emission rates. The Abel inversion results of two months of data (from 1 June to 31 July 2004) were analyzed for the layer mean and standard deviation as a function of latitude and local time. Statistical analysis of SABER data shows that the global difference between the mean and standard deviation profiles for the OH(vu = 7, 8, 9; ∆v …
Doppler Ducting Of Short-Period Gravity Waves By Midaltitude Tidal Wind Structure, Jonathan B. Snively, Victor P. Pasko, Michael J. Taylor, Wayne K. Hocking
Doppler Ducting Of Short-Period Gravity Waves By Midaltitude Tidal Wind Structure, Jonathan B. Snively, Victor P. Pasko, Michael J. Taylor, Wayne K. Hocking
Publications
Multiwavelength airglow image data depicting a short-period (∼4.9 min) atmospheric gravity wave characterized by a sharp leading front have been analyzed together with synoptic meteor radar wind data recorded simultaneously from Bear Lake Observatory, Utah (41.6°N, 111.6°W). The wind data suggest the presence of a semidiurnal tide with horizontal winds peaking at around 60 m/s along the SSE direction of motion (170° from north) of this short-period wave. It was found that the gravity wave was most probably ducted because of the Doppler shift imposed by this wind structure. A marked 180° phase shift was observed between the near-infrared OH …
Radial Velocity Observations Of The Extended Lunar Sodium Tail, E. J. Mierkiewicz, M. Line, F. L. Roesler, R. J. Oliversen
Radial Velocity Observations Of The Extended Lunar Sodium Tail, E. J. Mierkiewicz, M. Line, F. L. Roesler, R. J. Oliversen
Physical Sciences - Daytona Beach
We report the first velocity resolved sodium 5889.950 Å line profile observations of the lunar sodium tail observed in the anti-lunar direction near new Moon. These observations were made on 29 March 2006, 27 April 2006 and 28 April 2006 from Pine Bluff (WI) observatory with a double etalon Fabry-Perot spectrometer at a resolving power of ∼80,000. The observations were made within 2–14 hours from new Moon, pointing near the anti-lunar point. The average observed radial velocity of the lunar sodium tail in the vicinity of the anti-lunar point for the three nights reported was 12.4 km s−1 (from …
A Modeling Study Of O2 And Oh Airglow Perturbations Induced By Atmospheric Gravity Waves, Alan Z. Liu, Gary R. Swenson
A Modeling Study Of O2 And Oh Airglow Perturbations Induced By Atmospheric Gravity Waves, Alan Z. Liu, Gary R. Swenson
Physical Sciences - Daytona Beach
A one-dimensional model is used to investigate the relations between gravity waves and O2 and OH airglows perturbations. The amplitude and phase of the airglow perturbations induced by gravity waves (with period > 20 min) are calculated for different vertical wavelength (10–50 km) and damping rate. The model shows that for vertically propagating gravity waves, the amplitude of airglow perturbations observed from ground is larger for longer vertical wavelength, because of the smaller cancellation effect within each layer. The ratio of the amplitudes between O2 and OH is smaller for larger wave damping. For upward propagating (downward phase progression) …
A Simulation Study Of Space-Based Observations Of Gravity Waves In The Airglow Using Observed Aloha-93 Wave Parameters, Michael P. Hickey Ph.D., J. S. Brown
A Simulation Study Of Space-Based Observations Of Gravity Waves In The Airglow Using Observed Aloha-93 Wave Parameters, Michael P. Hickey Ph.D., J. S. Brown
Publications
We use gravity wave parameters derived from the ALOHA-93 campaign to model four gravity waves in airglow emissions as observed from the ground to numerically predict whether these waves could have been observed from space. In spite of encountering critical levels, some waves may still be observed in the airglow provided the critical level lies within the airglow emission region. One of the four waves experiences a critical level in the lower region of an airglow layer such that the disturbance to the volume emission rate would be effectively limited to a short distance along a satellite line of sight. …
Observations Of Persistent Leonid Meteor Trails 3. The ‘‘Glowworm’’, Jack D. Drummond, Brent W. Grime, Chester S. Gardner, Alan Z. Liu, Xinzhao Chu, Michael C. Kelley, Craig Kruschwitz, Timothy J. Kane
Observations Of Persistent Leonid Meteor Trails 3. The ‘‘Glowworm’’, Jack D. Drummond, Brent W. Grime, Chester S. Gardner, Alan Z. Liu, Xinzhao Chu, Michael C. Kelley, Craig Kruschwitz, Timothy J. Kane
Physical Sciences - Daytona Beach
A spectacular, well-observed Leonid meteor of visual magnitude -14.3 appeared on 17 November 1998 and left a lingering trail, dubbed the Glowworm, that was well studied. From a location on Kirtland Air Force Base, near Albuquerque, New Mexico, we obtained CCD images of the trail from 94 to 203 s after the meteor and recorded a video with an intensified camera for even longer. From information obtained with a sodium lidar half an hour after the meteor, we have determined that a gravity wave with a vertical wavelength of 2.4 km was responsible for the right-angled appearance of the trail. …
Geocoronal H-A [Alpha] Intensity Measurements Using The Wisconsin H-A [Alpha] Mapper Fabry-Perot Facility, S. Nossal, F. L. Roesler, J. Bishop, R. J. Reynolds, M. Haffner, S. Tufte, J. Percival, E. J. Mierkiewicz
Geocoronal H-A [Alpha] Intensity Measurements Using The Wisconsin H-A [Alpha] Mapper Fabry-Perot Facility, S. Nossal, F. L. Roesler, J. Bishop, R. J. Reynolds, M. Haffner, S. Tufte, J. Percival, E. J. Mierkiewicz
Physical Sciences - Daytona Beach
"The Wisconsin H-a [alpha] Mapper (WHAM), a remotely operable, semi-automated Fabry-Perot located at Kitt Peak Observatory, has been making an all-sky survey of interstellar hydrogen Balmer a [alpha] (H-a [alpha]) emissions since 1997. Using the annular summing spectroscopy technique, WHAM has acquired ~[approx.] 37,000 spectra to date, spanning almost 100 nights of observations. Since all of the galactic emission spectral data contain the terrestrial H-a [alpha] (6562.7 Å) emission line, these measurements constitute a rich source of geocoronal data for investigating natural variability in the upper atmosphere. The WHAM observations also serve as a benchmark for comparison with future …