Long-Term Wind Variability in the Tropical Pacific, Its Possible Causes and Effects

Abstract

It is shown that long-term trends in the meridional components of the trade wind circulations in both hemisphere over the Pacific are highly correlated with the precipitation falling in the intertropical convergence zone (ITCZ) over that region. The trends in the trade wind regime, on the one hand, seem to be caused by extratropical sea surface temperature (SST) anomalies in the North Pacific which influence atmospheric meridional temperature and pressure gradients. On the other hand, the release of latent heat in the ITCZ provides a self-enforcing feedback for the trade winds. A study of the recurrence frequency of precipitation surges over the Line Islands suggests the presence of three epoch (1911?28, 1929?62, 1963 to present) during which the Hadley cell circulation and attendant meteorological and oceanographic features showed different characteristics.