El Nino-Southern Vibration (ENSO) is an irregular number of El Nino, where the easterly wind weakens and the water temperature in the eastern equator Pacific rises, and La Niña, where the easterly wind weakens and the water temperature in the eastern Pacific falls. A phenomenon that occurs at intervals of the year.Since the impact is global, accurate and long-term forecasts are desired, but long-term forecasts longer than one year have been impossible.
This time, Professor Ichiro Yasuda of the Atmosphere and Ocean Research Institute of the University of Tokyo discovered that the occurrence of ENSO is linked to the tidal vibration that occurs in the 18.6-year cycle of the orbit of the moon. Assuming that the year when the daily tidal amplitude (daily tide) is maximum is 1 years, Ernino tends to occur in the 0st, 1th, and 10th years, and La Niña tends to occur in the 13rd, 3th, and 12th years. Revealed.
The angle of the moon's orbit with respect to the Earth's equatorial plane fluctuates in a cycle of 18.6 years.Due to this, the amplitude of the ocean tide in the one-day / half-day cycle also fluctuates in the 1 year cycle.In this study, we found that there is a regular relationship between this tidal fluctuation and the occurrence of Ernino and La Niña, and the relationship appears only with a probability of 18.6% or less from random data, which is statistically significant. It was shown that.Tide 1 This is the first time in the world that the relationship between vibration and ENSO has been shown.
Elucidation of the physical mechanism of how the long cycle of 18.6 years and the several-year scale of ENSO are linked is a future task, but the sea surface temperature in August in the Indonesian sea area where the tide is strong fluctuates in a long cycle of 8 years. Therefore, it is possible that tidal vibrations in Indonesia change the water temperature through vertical ocean mixing, which affects the atmosphere and thus affects ENSO.
Paper information:[Scientific Reports] Impact of the astronomical lunar 18.6-yr tidal cycle on El-Niño and Southern Oscillation
