The mean zonal flow response to Rossby wave and gravity wave forcing in the equatorial lower stratosphere: Relationship to the QBO. [QBO (quasi-biennial oscillation)]

Journal Article · Sun Sep 15 04:00:00 EDT 1991 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1991)048<2078:TMZFRT>2.0.CO;2· OSTI ID:5416599

Takahashi, M; Holton, J R ^[1]

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1. Univ. of Washington, Seattle, WA (United States)

Observations show that the westerly acceleration of the equatorial quasi-biennial oscillation (QBO) can be accounted for by Kelvin waves, but that there is a deficiency in the easterly acceleration due to Rossby-gravity waves. Rossby waves and westward propagating gravity waves have been suggested as alternative sources for the easterly acceleration. We have tested the possible role of these two wave modes in a two-dimensional model of the QBO. When the easterly acceleration is due to Rossby waves, the zonal-mean response is steady; when it is due to gravity waves, an oscillation with some features similar to the QBO occurs, but it is of short period and weak amplitude. A similar result occurs when a standing-wave forcing pattern is imposed. These results suggest that Rossby waves play only a minor role in the QBO, and that while the Rossby-gravity mode is essential, other gravity modes may also be important for the easterly phase. 12 refs., 22 figs.

• OSTI ID: 5416599
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 48:18; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ATMOSPHERIC CIRCULATION
FORCING FUNCTIONS
GRAVITY WAVES
METEOROLOGY
TROPICAL REGIONS
WAVE PROPAGATION