The Moon and El Niño
Abstract
Regional climates around the world display cycles corresponding to the 18.61-year maximum lunar declination (MLD) periodicity. We suggest that these cycles are created by a relationship between MLD and El Niño / Southern Oscillation (ENSO). Both equatorial Pacific sea-surface temperature and South Pacific atmospheric pressure significantly correlate with maximum lunar declination. Low MLDs are associated with warmer equatorial Pacific sea-surface temperatures and negative values of the Southern Oscillation Index. A lunar-influenced change in the Pacific gyre circulation presents a viable physical mechanism for explaining these relationships. We suggest that the gyre is enhanced by tidal forces under high MLDs, inducing cold-water advection into the equatorial region but is restricted by the weak tidal forcing of low MLDs thereby favoring El Niño episodes. An astronomical model utilizing this relationship produces a forecast of increased non-El Niño (either La Niña or neutral) activity for the early part of this decade.
- Publication:
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Geophysical Research Letters
- Pub Date:
- January 2001
- DOI:
- 10.1029/2000GL012117
- Bibcode:
- 2001GeoRL..28...25C
- Keywords:
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- Oceanography: Physical: El Nino