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Deep current measurements suggest long waves in the eastern equatorial pacific.
Science (New York, N.Y.)
|September 3, 1976
Summary
Researchers detected a 25-day westward-propagating wave near the equator during the 1975 El Niño expedition. This oceanic wave matches theoretical models of equatorial Rossby waves.
Area of Science:
- Oceanography
- Climate Science
- Geophysics
Background:
- The 1975 El Niño expedition aimed to study oceanic conditions.
- El Niño events are associated with significant climate anomalies.
- Understanding equatorial wave dynamics is crucial for climate modeling.
Purpose of the Study:
- To analyze near-bottom current data collected during the 1975 El Niño expedition.
- To identify and characterize any significant oceanic oscillations.
- To compare observed phenomena with theoretical models of equatorial waves.
Main Methods:
- Deployment of conventional and electric field near-bottom current recorders.
- Hydrographic observations were conducted concurrently.
- Analysis of current meter data for period, wavelength, amplitude, and propagation speed.
Main Results:
- An oscillation with a 25-day period was recorded.
- The wave exhibited a wavelength of approximately 1000 km and an amplitude of 0.04 m/s.
- The oscillation propagated westward at about 0.5 m/s.
Conclusions:
- The observed westward-propagating wave matches theoretical models of a first-mode baroclinic Rossby wave.
- The wave was found to be trapped at the equator.
- These findings enhance understanding of equatorial ocean dynamics during El Niño events.
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