Aspects of the Kelvin wave response to episodic wind forcing

Journal Article · Tue May 15 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JC095iC05p07289· OSTI ID:5084514

Giese, B S ^[1]; Harrison, D E ^[2]

---

1. Joint Inst. for the Study of Atmospheres and Oceans, Seattle, WA (United States)
2. NOAA, Seattle, WA (United States)

During El Nino-Southern Oscillation periods, the presence of westerly episodes comprises much of the low-frequency relaxation of the trades over the central and western Pacific. In this paper, the authors describe the oceanic Kelvin pulse response to a single idealized episode of westerly wind stress, using results from linear theory as well as from a 27-level general circulation model. Because of changing vertical thermal structure across the Pacific, the vertical structure of Kelvin pulses is altered as they propagate away from the forcing region. When stratification typical of the western and eastern Pacific is used, the conservation of energy flux predicts a reduction of surface currents associated with the first baroclinic mode and an enhancement of surface currents associated with the second baroclinic mode. The idealized wind anomaly is also used to drive an ocean general circulation model. When the wind anomaly is weak the model Kelvin response agrees with predictions of linear theory. For more realistic strong forcing there are three important deviations from linear theory: the amplitude of low baroclinic modes increases; the amplitude of higher baroclinic modes decreases; and the phase speed increases. In the presence of realistic oceanic background conditions, response in the equatorial waveguide is complicated by the equatorial undercurrent, a sloping thermocline and instability waves. Model sea surface temperature warming at the coast of South America is dominated by the second barocline mode, consistent with the results derived from linear theory.

• OSTI ID: 5084514
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:C5; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110
540310* -- Environment
Aquatic-- Basic Studies-- (1990-)
AMBIENT TEMPERATURE
ATMOSPHERIC CIRCULATION
CORRELATIONS
CURRENTS
FUNCTIONS
GENERAL CIRCULATION MODELS
MATHEMATICAL MODELS
MORPHOLOGY
OCEANIC CIRCULATION
PACIFIC OCEAN
RESPONSE FUNCTIONS
SEAS
SOUTHERN OSCILLATION
STRATIFICATION
SURFACE WATERS
WATER CURRENTS
WAVE PROPAGATION
WIND