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- Publications (16)
- Gravity waves (4)
- Diurnal tide (2)
- Eddy diffusion (2)
- Mesospheric dynamics (2)
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- Na flux (2)
- Acoustic-gravity waves (1)
- Airglow (1)
- Airglow layers (1)
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- Dissipating gravity waves (1)
- Dynamic instability (1)
- Dynamical flux (1)
- Dynamical instabilities (1)
- Feature extraction (1)
- Flux of momentum and energy (1)
- Gravity wave (1)
- Heat flux (1)
- Lidar (1)
- Maui mesosphere and lower thermosphere (1)
- Mesopause region (1)
- Mesopheric dynamics (1)
- Mesosphere (1)
- Mesosphere and lower thermosphere (1)
Articles 1 - 27 of 27
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Characteristics Of Short-Period Wavelike Features Near 87 Km Altitude From Airglow And Lidar Observations Over Maui, J. H. Hecht, A. Z. Liu, R. L. Walterscheid, S. J. Franke, R. J. Rudy, M. J. Taylor, P. -D. Pautet
Characteristics Of Short-Period Wavelike Features Near 87 Km Altitude From Airglow And Lidar Observations Over Maui, J. H. Hecht, A. Z. Liu, R. L. Walterscheid, S. J. Franke, R. J. Rudy, M. J. Taylor, P. -D. Pautet
Alan Z Liu
Small-scale (less than 15 km horizontal wavelength) wavelike structures known as ripples are a common occurrence in OH airglow images. Recent case studies attribute their origin to the presence of either convective or dynamical instabilities. However, little is known about their frequency of occurrence and period. The Maui-MALT Observatory, located at Mt. Haleakala, is instrumented with a Na wind/temperature lidar, which allows the determination of whether the atmosphere is dynamically or convectively unstable, and a fast OH airglow camera which takes images every 3 s with a sensitivity high enough to see the ripples. This study reports on 2 months …
Observations Of Persistent Leonid Meteor Trails 2. Photometry And Numerical Modeling, C. A. Kruschwitz, M. C. Kelley, C. S. Gardner, G. Swenson, A. Z. Liu, X. Chu, J. D. Drummond, B. W. Grime, W. T. Armstrong, J. M. C. Plane, P. Jenniskens
Observations Of Persistent Leonid Meteor Trails 2. Photometry And Numerical Modeling, C. A. Kruschwitz, M. C. Kelley, C. S. Gardner, G. Swenson, A. Z. Liu, X. Chu, J. D. Drummond, B. W. Grime, W. T. Armstrong, J. M. C. Plane, P. Jenniskens
Alan Z Liu
During the 1998 Leonid meteor shower, multi-instrument observations of persistent meteor trains were made from the Starfire Optical Range on Kirtland Air Force Base, New Mexico, and from a secondary site in nearby Placitas, New Mexico. The University of Illinois Na resonance lidar measured the Na density and temperature in the trains, while various cameras captured images and videos of the trains, some of which were observed to persist for more than 30 min. The Na density measurements allow the contribution of Na airglow to the observed train luminescence to be quantified for the first time. To do this, persistent …
Measuring Eddy Heat And Constituent Fluxes With High-Resolution Na And Fe Doppler Lidars, Chester S. Gardner, Alan Z. Liu
Measuring Eddy Heat And Constituent Fluxes With High-Resolution Na And Fe Doppler Lidars, Chester S. Gardner, Alan Z. Liu
Alan Z Liu
Inferring The Global Cosmic Dust Influx To The Earth’S Atmosphere From Lidar Observations Of The Vertical Flux Of Mesospheric Na, Chester S. Gardner, Alan Z. Liu, Dan Marsh, Wuhu Feng, John Plane
Inferring The Global Cosmic Dust Influx To The Earth’S Atmosphere From Lidar Observations Of The Vertical Flux Of Mesospheric Na, Chester S. Gardner, Alan Z. Liu, Dan Marsh, Wuhu Feng, John Plane
Alan Z Liu
Removing Milky Way From Airglow Images Using Principle Component Analysis, Zhenhua Li, Alan Z. Liu, Gulamabas G. Sivjee
Removing Milky Way From Airglow Images Using Principle Component Analysis, Zhenhua Li, Alan Z. Liu, Gulamabas G. Sivjee
Alan Z Liu
Gravity Wave Characteristics In The Lower Atmosphere At South Pole, Matt Pfenniger, Alan Z. Liu, George C. Papen, Chester S. Gardner
Gravity Wave Characteristics In The Lower Atmosphere At South Pole, Matt Pfenniger, Alan Z. Liu, George C. Papen, Chester S. Gardner
Alan Z Liu
A 4-year (1993-1996) temperature and wind data set obtained from over 2000 high-resolution balloon soundings at South Pole is used to study gravity wave characteristics in the atmosphere and lower stratosphere. Extensive analyses of energy density, spectra, and static stability are performed to present a comprehensive view of the gravity waves are ubiquitous and often fairly strong at the South Pole, even though the generation mechanisms are not clear. Gravity wave characteristics are, in general, similar to those obtained at other high-latitude southern hemisphere stations. Potential energies vary between about 0.5 J/kg and 5 J/kg with season and altitude. Variations …
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
Alan Z Liu
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 = 2) emission …
Vertical Heat And Constituent Transport In The Mesopause Region By Dissipating Gravity Waves At Maui, Hawaii (20.7ºn), And Starfire Optical Range, New Mexico (35ºn), Alan Z. Liu, Chester S. Gardner
Vertical Heat And Constituent Transport In The Mesopause Region By Dissipating Gravity Waves At Maui, Hawaii (20.7ºn), And Starfire Optical Range, New Mexico (35ºn), Alan Z. Liu, Chester S. Gardner
Alan Z Liu
Vertical heat flux profiles induced by dissipating gravity waves in the mesopause region (85–100 km altitude) are derived from Na lidar measurements of winds and temperatures at Maui (20.7ºN, 156.3ºW), Hawaii, and compared with earlier results from Starfire Optical Range (SOR, 35.0ºN, 106.5ºW), New Mexico. The heat flux profile at SOR has a single downward maximum of 2.25 ± 0.3 K m/s at 88 km, while the profile at Maui has two downward maxima of 1.25 ± 0.5 K m/s and 1.40 ± 0.5 K m/s at 87 and 95 km, respectively. The common maximum below 90 km can be …
Characteristics Of Instabilities In The Mesopause Region Over Maui, Hawaii, Feng Li, Alan Z. Liu, Gary R. Swenson
Characteristics Of Instabilities In The Mesopause Region Over Maui, Hawaii, Feng Li, Alan Z. Liu, Gary R. Swenson
Alan Z Liu
Characteristics of convective and dynamical instabilities in the mesopause region (between 85 and 100 km) over Maui, Hawaii (20.7ºN, 156.3ºW) are investigated using 19 nights, ~133 hours of high-resolution wind and temperature data obtained by the University of Illinois Na wind/temperature lidar during the Maui Mesosphere and Lower Thermosphere (Maui MALT) campaigns. The mean probabilities of convective and dynamical instabilities are observed to be ~3 and 10%, respectively, but there is considerable night-to-night variation. At any given time the probability that an unstable condition is found at some altitudes in the 85–100 km range is 90%. The Maui MALT data …
Vertical Dynamical Transport Of Mesospheric Constituents By Dissipating Gravity Waves, Alan Z. Liu, Chester S. Gardner
Vertical Dynamical Transport Of Mesospheric Constituents By Dissipating Gravity Waves, Alan Z. Liu, Chester S. Gardner
Alan Z Liu
Over 400 h of Na wind/temperature lidar observations, obtained at the Star5re Optical Range, NM, are used to study the vertical dynamical transport of Na in the mesopause region between 85 and 100 km. Dynamical transport occurs when dissipating, non-breaking gravity waves impart a net vertical displacement in atmospheric constituents as they propagate through a region. We show that the vertical constituent flux can be related in a simple way to the vertical heat flux. Breaking gravity waves also contribute to eddy transport by generating turbulence. Because eddy transport is a mixing process, it only occurs in the presence of …
Estimation Of Gravity Wave Momentum Flux With Spectroscopic Imaging, Jing Tang, Farzad Kamalabadi, Steven J. Franke, Alan Z. Liu, Gary R. Swenson
Estimation Of Gravity Wave Momentum Flux With Spectroscopic Imaging, Jing Tang, Farzad Kamalabadi, Steven J. Franke, Alan Z. Liu, Gary R. Swenson
Alan Z Liu
Atmospheric gravity waves play a significant role in the dynamics and thermal balance of the upper atmosphere. In this paper, we present a novel technique for automated and robust calculation of momentum flux of high-frequency quasi-monochromatic wave components from spectroscopic imaging and horizontal radar wind measurements. Our approach uses the two-dimensional (2-D) cross periodogram of two consecutive Doppler-shifted time-differenced (TD) images to identify wave components and estimate intrinsic wave parameters. Besides estimating the average perturbation of dominant waves in the whole field of view, this technique applies 2-D short-space Fourier transform to the TD images to identify localized wave events. …
O(1s), Oh, And O2(B) Airglow Layer Perturbations Due To Agws And Their Implied Effects On The Atmosphere, Fabio Vargas, Gary Swenson, Alan Liu, Delano Gobbi
O(1s), Oh, And O2(B) Airglow Layer Perturbations Due To Agws And Their Implied Effects On The Atmosphere, Fabio Vargas, Gary Swenson, Alan Liu, Delano Gobbi
Alan Z Liu
The O(1S) (green line) night airglow emission in response to atmospheric gravity wave (AGW) perturbations was simulated with a linear, one-dimensional model. The results were combined with previously modeled O2(b, 0–1) atmospheric band and OH Meinel band emission response (Liu and Swenson, 2003) to derive amplitude and phase relations among multiple airglow layers in response to gravity waves with various intrinsic parameters and damping rates (β). The simulations show that the vertical profile of the standard deviation of the perturbed green line volume emission rate (VER) has a centroid altitude that is 3 km …
An Overview Of Observations Of Unstable Layers During The Turbulent Oxygen Mixing Experiment (Tomex), J. H. Hecht, Alan Z. Liu, R. L. Bishop, J. H. Clemmons, C. S. Gardner, M. F. Larsen, R. G. Roble, G. R. Swenson, R. L. Walterscheid
An Overview Of Observations Of Unstable Layers During The Turbulent Oxygen Mixing Experiment (Tomex), J. H. Hecht, Alan Z. Liu, R. L. Bishop, J. H. Clemmons, C. S. Gardner, M. F. Larsen, R. G. Roble, G. R. Swenson, R. L. Walterscheid
Alan Z Liu
The Turbulent Oxygen Mixing Experiment (TOMEX) was designed to measure the atmospheric response to the existence of unstable layers as determined by wind and temperature measurements from 80 to 105 km. TOMEX combined Na lidar measurements, from Starfire Optical Range in Albuquerque, New Mexico, with a launch of a payload from White Sands Missile Range, located between 100 and 150 km south of Starfire. The payload included a trimethyl aluminum chemical release to measure winds and diffusion, a 5-channel ionization gauge to measure neutral density fluctuations at high vertical resolution, and a 3-channel photometer experiment to measure atomic oxygen related …
A Model For Calculating Acoustic Gravity Wave Energy And Momentum Flux In The Mesosphere From Oh Airglow, Gary R. Swenson, Alan Z. Liu
A Model For Calculating Acoustic Gravity Wave Energy And Momentum Flux In The Mesosphere From Oh Airglow, Gary R. Swenson, Alan Z. Liu
Alan Z Liu
Acoustic gravity and tidal waves propagating in the mesosphere/lower thermosphere (80-110 km) perturb the airglow layer intensities. The OH airglow has recently been modeled to determine the relationship between the relative perturbed atmospheric density and temperature (ρ’/ ρ, T’/T) to the OH intensity ( I’OH/IOH ) at the OH emission altitudes [Swenson and Gardner, 1997]. A model is presented here which relates wave perturbed OH airglow to the wave energy and momentum flux as they propagate through the emission layer. The model is dependent on the wave horizontal and vertical wavelengths (or phase speed as related through the dispersion relationship), …
Diurnal Variation Of Gravity Wave Momentum Flux And Its Forcing On The Diurnal Tide, Alan Z. Liu, Xian Lu, Steven Franke
Diurnal Variation Of Gravity Wave Momentum Flux And Its Forcing On The Diurnal Tide, Alan Z. Liu, Xian Lu, Steven Franke
Alan Z Liu
Instability Structures During Periods Of Large Richardson Number (Ri > ¼): Evidence Of Parametric Instability, Richard L. Walterscheid, L J. Gelinas, James H. Hecht, Alan Z. Liu
Instability Structures During Periods Of Large Richardson Number (Ri > ¼): Evidence Of Parametric Instability, Richard L. Walterscheid, L J. Gelinas, James H. Hecht, Alan Z. Liu
Alan Z Liu
Meteor-Radar Observed Mesospheric Semi-Annual Oscillation (Sao) And Quasi-Biennial Oscillation (Qbo) Over Maui, Hawaii, Tao Li, Alan Z. Liu, Xian Lu, Zhenhua Li, Steven Franke, Gary R. Swenson, Xiankang Dou
Meteor-Radar Observed Mesospheric Semi-Annual Oscillation (Sao) And Quasi-Biennial Oscillation (Qbo) Over Maui, Hawaii, Tao Li, Alan Z. Liu, Xian Lu, Zhenhua Li, Steven Franke, Gary R. Swenson, Xiankang Dou
Alan Z Liu
No abstract provided.
Spectral Energy Transfer Of Atmospheric Gravity Waves Through Sum And Difference Nonlinear Interactions, Kaiming Huang, Alan Z. Liu, Shaodong Zhang, Fan Yi, Zhenhua Li
Spectral Energy Transfer Of Atmospheric Gravity Waves Through Sum And Difference Nonlinear Interactions, Kaiming Huang, Alan Z. Liu, Shaodong Zhang, Fan Yi, Zhenhua Li
Alan Z Liu
No abstract provided.
Momentum Budget Of The Migrating Diurnal Tide In The Whole Atmosphere Community Climate Model At Vernal Equinox, Xian Lu, Alan Z. Liu, Han-Li Liu, Jie Yue
Momentum Budget Of The Migrating Diurnal Tide In The Whole Atmosphere Community Climate Model At Vernal Equinox, Xian Lu, Alan Z. Liu, Han-Li Liu, Jie Yue
Alan Z Liu
No abstract provided.
Gravity Wave Characteristics From Oh Airglow Imager Over Maui, Alan Z. Liu, Xian Lu, Zhenhua Li, Gary R. Swenson, Steven Franke
Gravity Wave Characteristics From Oh Airglow Imager Over Maui, Alan Z. Liu, Xian Lu, Zhenhua Li, Gary R. Swenson, Steven Franke
Alan Z Liu
No abstract provided.
Seasonal Variability Of The Diurnal Tide In The Mesosphere And Lower Thermosphere Over Maui, Hawaii (20.7˚N, 156.3˚W), Xian Lu, Alan Z. Liu, Jens Oberheide, Qian Wu, Tao Li, Zhenhua Li, Gary R. Swenson, Steven J. Franke
Seasonal Variability Of The Diurnal Tide In The Mesosphere And Lower Thermosphere Over Maui, Hawaii (20.7˚N, 156.3˚W), Xian Lu, Alan Z. Liu, Jens Oberheide, Qian Wu, Tao Li, Zhenhua Li, Gary R. Swenson, Steven J. Franke
Alan Z Liu
No abstract provided.
Wave-Induced Transport Of Atmospheric Constituents And Its Effect On The Mesospheric Na Layer, Chester S. Gardner, Alan Z. Liu
Wave-Induced Transport Of Atmospheric Constituents And Its Effect On The Mesospheric Na Layer, Chester S. Gardner, Alan Z. Liu
Alan Z Liu
No abstract provided.
Overturning Instability In The Mesosphere And Lower Thermosphere: Analysis Of Instability Conditions In Lidar Data, Lucas Hurd, Miguel F. Larsen, Alan Z. Liu
Overturning Instability In The Mesosphere And Lower Thermosphere: Analysis Of Instability Conditions In Lidar Data, Lucas Hurd, Miguel F. Larsen, Alan Z. Liu
Alan Z Liu
No abstract provided.
Gravity Wave Propagation And Dissipation From The Stratosphere To The Lower Thermosphere, Xian Lu, Alan Z. Liu, Gary R. Swenson, Tao Li
Gravity Wave Propagation And Dissipation From The Stratosphere To The Lower Thermosphere, Xian Lu, Alan Z. Liu, Gary R. Swenson, Tao Li
Alan Z Liu
No abstract provided.
A Model Study Of The Effects Of Winds On Concentric Rings Of Gravity Waves From A Convective Plume Near Fort Collins On 11 May 2004, Sharon L. Vadas, Jia Yue, Chiao-Yao She, Peter A. Stamus, Alan Z. Liu
A Model Study Of The Effects Of Winds On Concentric Rings Of Gravity Waves From A Convective Plume Near Fort Collins On 11 May 2004, Sharon L. Vadas, Jia Yue, Chiao-Yao She, Peter A. Stamus, Alan Z. Liu
Alan Z Liu
No abstract provided.
Estimate Eddy Diffusion Coefficients From Gravity Wave Vertical Momentum And Heat Fluxes, Alan Z. Liu
Estimate Eddy Diffusion Coefficients From Gravity Wave Vertical Momentum And Heat Fluxes, Alan Z. Liu
Alan Z Liu
No abstract provided.
Sources Of Gravity Waves In The Lower Stratosphere Above South Pole, Zhenhua Li, Walter A. Robinson, Alan Z. Liu
Sources Of Gravity Waves In The Lower Stratosphere Above South Pole, Zhenhua Li, Walter A. Robinson, Alan Z. Liu
Alan Z Liu
No abstract provided.