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Physical Sciences and Mathematics Commons™

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Oceanography and Atmospheric Sciences and Meteorology

Selected Works

Publications

Articles 1 - 21 of 21

Full-Text Articles in Physical Sciences and Mathematics

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 Aug 2014

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

Estimates of the global influx of cosmic dust are highly uncertain, ranging from 0.4–110 t/d. All
meteoric debris that enters the Earth’s atmosphere is eventually transported to the surface. The downward
fluxes of meteoric metals like mesospheric Na and Fe, in the region below where they are vaporized and
where the majority of these species are still in atomic form, are equal to their meteoric ablation influxes,
which in turn, are proportional to the total cosmic dust influx. Doppler lidar measurements of mesospheric Na
fluxes made throughout the …

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Removing Milky Way From Airglow Images Using Principle Component Analysis, Zhenhua Li, Alan Z. Liu, Gulamabas G. Sivjee Feb 2014

Removing Milky Way From Airglow Images Using Principle Component Analysis, Zhenhua Li, Alan Z. Liu, Gulamabas G. Sivjee

Alan Z Liu

Airglow imaging is an effective way to obtain atmospheric gravity wave information in the airglow layers in the upper mesosphere and the lower thermosphere. Airglow images are often contaminated by the Milky Way emission. To extract gravity wave parameters correctly, the Milky Way must be removed. The paper demonstrates that principal component analysis (PCA) can effectively represent the dominant variation patterns of the intensity of airglow images that are associated with the slow moving Milky Way features. Subtracting this PCA reconstructed field reveals gravity waves that are otherwise overwhelmed by the strong spurious waves associated with the Milky Way. Numerical …

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A Model For Calculating Acoustic Gravity Wave Energy And Momentum Flux In The Mesosphere From Oh Airglow, Gary R. Swenson, Alan Z. Liu Sep 2013

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), …

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Sources Of Gravity Waves In The Lower Stratosphere Above South Pole, Zhenhua Li, Walter Robinson, Alan Liu Aug 2013

Sources Of Gravity Waves In The Lower Stratosphere Above South Pole, Zhenhua Li, Walter Robinson, Alan Liu

Zhenhua Li

No abstract provided.

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Meteor-Radar Observed Mesospheric Semi-Annual Oscillation (Sao) And Quasi-Biennial Oscillation (Qbo) Over Maui, Hawaii, Tao Li, Alan Liu, Xian Lu, Zhenhua Li, Steven Franke, Gary Swenson, Xiankang Dou Aug 2013

Meteor-Radar Observed Mesospheric Semi-Annual Oscillation (Sao) And Quasi-Biennial Oscillation (Qbo) Over Maui, Hawaii, Tao Li, Alan Liu, Xian Lu, Zhenhua Li, Steven Franke, Gary Swenson, Xiankang Dou

Zhenhua Li

No abstract provided.

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Gravity Wave Characteristics From Oh Airglow Imager Over Maui, Alan Liu, Xian Lu, Zhenhua Li, Gary Swenson, Steven Franke Aug 2013

Gravity Wave Characteristics From Oh Airglow Imager Over Maui, Alan Liu, Xian Lu, Zhenhua Li, Gary Swenson, Steven Franke

Zhenhua Li

No abstract provided.

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Diurnal Variation Of Gravity Wave Momentum Flux And Its Forcing On The Diurnal Tide, Alan Z. Liu, Xian Lu, Steven Franke Feb 2013

Diurnal Variation Of Gravity Wave Momentum Flux And Its Forcing On The Diurnal Tide, Alan Z. Liu, Xian Lu, Steven Franke

Alan Z Liu

The diurnal variation of gravity wave (GW) momentum flux is derived from the 5 years of meteor radar wind measurements at Maui, Hawaii. The amplitude and phase relationships between the GW forcing and the diurnal tide are analyzed by calculating their equivalent Rayleigh frictions. The results show that the GW momentum flux is clearly modulated by the diurnal tide. The forcing from the momentum flux convergence has strong effects on both the amplitude and phase of the diurnal tide. They can reach 80 ms ‚àí‚Äâ1 day ‚àí‚Äâ1 for the amplitude and 15 h day ‚àí‚Äâ1 for the phase. The GW …

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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 Dec 2012

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

The commonly used criteria for shear and convective instabilities were developed for steady horizontally uniform background flows. However, the formalism that rigorously addresses the instability of waves on a basic state modulated by a primary wave is Floquet theory in which the basic state includes a wave. A Floquet system supports parametric instabilities when conventional Richardson number (Ri) criteria indicate that the system is stable. In a study of small-scale instability structures during the Maui MALT campaign, Hecht et al. (2005) noted that there were occurrences of ripple (instability) structure when the conventional criteria indicated stable conditions. …

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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 Mar 2012

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.

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Spectral Energy Transfer Of Atmospheric Gravity Waves Through Sum And Difference Nonlinear Interactions, Kaiming Huang, Alan Z. Liu, Shaodong Zhang, Fan Yi, Zhenhua Li Feb 2012

Spectral Energy Transfer Of Atmospheric Gravity Waves Through Sum And Difference Nonlinear Interactions, Kaiming Huang, Alan Z. Liu, Shaodong Zhang, Fan Yi, Zhenhua Li

Zhenhua Li

No abstract provided.

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Spectral Energy Transfer Of Atmospheric Gravity Waves Through Sum And Difference Nonlinear Interactions, Kaiming Huang, Alan Z. Liu, Shaodong Zhang, Fan Yi, Zhenhua Li Feb 2012

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.

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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 Dec 2011

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.

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Gravity Wave Characteristics From Oh Airglow Imager Over Maui, Alan Z. Liu, Xian Lu, Zhenhua Li, Gary R. Swenson, Steven Franke Nov 2011

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.

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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 Sep 2011

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

Zhenhua Li

No abstract provided.

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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 Sep 2011

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.

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Wave-Induced Transport Of Atmospheric Constituents And Its Effect On The Mesospheric Na Layer, Chester S. Gardner, Alan Z. Liu Oct 2010

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.

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Overturning Instability In The Mesosphere And Lower Thermosphere: Analysis Of Instability Conditions In Lidar Data, Lucas Hurd, Miguel F. Larsen, Alan Z. Liu Dec 2008

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.

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Gravity Wave Propagation And Dissipation From The Stratosphere To The Lower Thermosphere, Xian Lu, Alan Z. Liu, Gary R. Swenson, Tao Li Dec 2008

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.

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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 Dec 2008

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.

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Estimate Eddy Diffusion Coefficients From Gravity Wave Vertical Momentum And Heat Fluxes, Alan Z. Liu Dec 2008

Estimate Eddy Diffusion Coefficients From Gravity Wave Vertical Momentum And Heat Fluxes, Alan Z. Liu

Alan Z Liu

No abstract provided.

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Sources Of Gravity Waves In The Lower Stratosphere Above South Pole, Zhenhua Li, Walter A. Robinson, Alan Z. Liu Dec 2008

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.

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