Tropical Pacific control of intraseasonal oscillations off Chile by way of oceanic and atmospheric pathways

Sea level, current, satellite wind data and a simple model of wind-forced, low frequency waves are used to study the origins of strong, observed intraseasonal variability in the ocean and atmosphere off Chile. There intraseasonal wind fluctuations are correlated to wind fluctuations in the equatorial Pacific, associated with the Madden-Julian Oscillation. Results suggest intraseasonal teleconnections via two distinct atmospheric pathways. Very simple model simulations forced by satellite winds from the equator and the South American coast compare well with observed fluctuations of currents and sea level off central Chile. There most of this intraseasonal variability, particularly during summer and during El Niño events, arrives as free, oceanic, coastal trapped waves via oceanic, equatorial Kelvin waves, forced by tropical Pacific winds. South of 20S, some oceanic intraseasonal variability is forced by local winds associated with the atmospheric teleconnections.