Physical Sciences and Mathematics Commons^™

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. …

Tomographic Imaging Of Airglow From Airborne Spectroscopic Measurements, D. Scott Anderson, Gary Swenson,, Farzad Kamalabadi, Alan Liu

Alan Z Liu

A description is given of the methodology based on a single, aircraft-mounted spectroscopic imager to tomographically reconstruct airglow perturbations induced by atmospheric gravity waves. In this configuration, the imager passes under the airglow structure to gather multiple-angle views of the wave structure in a relatively short amount of time. Under the assumption that the airglow structure does not change significantly during the acquisition interval, the data can be tomographically inverted to estimate the 2D (horizontal–vertical) airglow structure. We develop an inversion strategy for this image formation task and illustrate its applicability by inverting time-sequential imaging data taken from different vantage …

High Frequency Gravity Waves Observed In Oh Airglow At Starfire Optical Range, Nm: Seasonal Variations In Momentum Flux, Jing Tang, Alan Z. Liu, Gary R. Swenson

Alan Z Liu

Airglow imager and Na wind/temperature lidar measurements at Starfire Optical Range, New Mexico (35ºN, 107ºW) are used to estimate the seasonal variation of the vertical fluxes of horizontal momentum carried by high frequency Atmospheric Gravity Waves (AGWs). The cross-correlation coefficients between the vertical and horizontal wind perturbations were calculated from the OH airglow imager data collected during 32 nights in 1998, 1999 and 2000. The RMS wind velocities were deduced from the lidar measurements. The combined information was used to estimate the upper limit of the momentum flux. The meridional component of the vertical flux of horizontal momentum was observed …

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 …

Observations Of Overturning In The Upper Mesosphere And Lower Thermosphere, M. F. Larsen, Alan Z. Liu, C. S. Gardner, M. C. Kelley, S. Collins, J. Friedman, J. H. Hecht

Alan Z Liu

A number of observations of the sodium density primarily in the mesosphere and lower thermosphere (but also of the electron density structure) have shown what appears to be overturning or convective roll cells near the transition from the mesosphere to the lower thermosphere. The cells are found in the region between 95 and 105 km and occur near the boundary between the region of lower stability in the mesosphere and the region of higher stability in the lower thermosphere. The vertical scale for the rolls is ~5–6 km, and the timescale is ~1–3 hours. The rolls occur in a region …

Seasonal And Nocturnal Variations Of The Mesospheric Sodium Layer At Starfire Optical Range, New Mexico, Hu Xiong, Chester S. Gardner, Alan Z. Liu

Alan Z Liu

The seasonal variations of the mesospheric sodium layer structure over Starfire Optical Range (SOR: 35ºN, 106.5ºW), New Mexico are characterized using 46 night data of Na wind/temperature lidar observations collected from Jan. 1998 to May 2000. The column abundance has a mean value of 5.06 x 109 cm -2 and strong annual oscillations of with a maximum in November and a minimum in June and July. The annual mean rms width of the sodium layer is 4.30 km and the mean centroid height is 91.60 km. Semiannual oscillations are evident in seasonal variations of the rms width and the centroid …

Unstable Layers In The Mesopause Region Observed With Na Lidar During The Turbulent Oxygen Mixing Experiment (Tomex) Campaign, Alan Z. Liu, Raymond G. Roble, James H. Hecht, Miguel F. Larsen, Chester S. Gardner

Alan Z Liu

The Na wind/temperature lidar located at Starfire Optical Range near Albuquerque, New Mexico, provided real time measurements of wind, temperature, and Na density in the mesopause region during the TOMEX rocket campaign in October 2000. The state of the atmosphere in which the rocket was launched into was examined using the lidar measurements. Both convectively and dynamically unstable layers were observed at various times and altitudes during the night. The low convective stability region below 90 km was found to be associated with the diurnal tide. The unstable layers are the combined results of wave and tidal perturbations. Comparison with …

Tomex: A Comparison Of Lidar And Sounding Rocket Chemical Tracer, M. F. Larsen, Alan Z. Liu, R. L. Bishop, J. H. Hecht

Alan Z Liu

On October 26, 2000, a Black Brant V sounding rocket carrying a chemical tracer release was launched from the rocket range at White Sands, New Mexico, as part of the Turbulent Oxygen Mixing Experiment (TOMEX). The releases occurred approximately 150 km from the location of the Starfire Optical Range where the University of Illinois sodium lidar was operated to measure winds and temperatures in the mesosphere and lower thermosphere. The geometry for the experiment was such that the lidar beam was able to intersect the release point for the chemical tracer trail on the upleg part of the flight near …

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

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

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

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

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

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

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

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

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

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

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

Alan Z Liu

No abstract provided.

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

Alan Z Liu

No abstract provided.