Instability at the winter stratopause: A mechanism for the 4-day wave

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1993)050<3928:IATWSA>2.0.CO;2· OSTI ID:7117585

Manney, G L ^[1]; Randel, W J ^[2]

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1. California Institute of Technology, Pasadena, CA (United States)
2. National Center for Atmospheric Research, Boulder, CO (United States)

Studies using climatological fields in a three-dimensional stability model show unstable modes near the polar winter stratopause with periods near 4 days. The calculated modes exhibit equatorward momentum and heat fluxes near the stratopause, similar to characteristics of observed 4-day wave events, demonstrating that both baroclinc and barotropic processes are important for this instability. The baroclinic and barotropic components are considered separately by selectively removing either horizontal or vertical shear from the background flow. Although both situations reveal instability, growth rates are very slow; realistic growth rates occur only for climatological flows including horizontal and vertical shears. Similar unstable, fast-moving waves are found near the polar stratopause for several winter months in both hemispheres. 34 refs., 15 figs.

• OSTI ID: 7117585
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 50:23; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ATMOSPHERIC CIRCULATION
CRYOSPHERE
EARTH ATMOSPHERE
MATHEMATICAL MODELS
METEOROLOGY
POLAR REGIONS
SEASONAL VARIATIONS
STRATOSPHERE
THREE-DIMENSIONAL CALCULATIONS
VARIATIONS
WAVE PROPAGATION