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Alan Z Liu

Selected Works

Dynamic instability

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Gravity Wave Characteristics In The Lower Atmosphere At South Pole, Matt Pfenniger, Alan Z. Liu, George C. Papen, Chester S. Gardner Oct 2013

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 …


Measurements Of Atmospheric Stability In The Mesopause Region At Starfire Optical Range, Nm, Yucheng Zhao, Alan Z. Liu, Chester S. Gardner Oct 2013

Measurements Of Atmospheric Stability In The Mesopause Region At Starfire Optical Range, Nm, Yucheng Zhao, Alan Z. Liu, Chester S. Gardner

Alan Z Liu

The structure and seasonal variations of static (convective) and dynamic (shear) instabilities in the mesopause region (80–105 km) are examined using high-resolution wind and temperature data obtained with a Na lidar at the Starfire Optical Range, NM. The probabilities of static and dynamic instability are sensitive functions of N2/S2, where N is the buoyancy frequency and S is the total vertical shear in the horizontal winds. The mesopause region is most stable in summer when the mesopause is low, N is large and S is small. Monthly mean N2/S2 varies from a maximum value of about 1.06 in mid-summer to …