Research Product

In the boreal fall of 2005, the effects of tropical instability waves (TIW) appear as oscillations within the sea surface temperature (SST), meridional current (Vy), and thermocline (20°C) in the eastern equatorial Pacific. Within the Galápagos Archipelago, a strong 3-wave succession of ~15-day period TIW in Sep and Oct 2005 registered a large subsurface (5-m) temperature and water level response at four moorings. Upwelling speeds of ~5.0 m day-1 are estimated for the central archipelago during the TIW, dropping temperatures by ~7°C within a week. Meridional oscillations of the equatorial front (EF) by the TIW are observed from 110°W east to the archipelago, except near 95°W where the changes of the thermocline are concurrent to those of the SST. A significant biological response to the TIW is observed throughout the archipelago. Coincident with coldest temperatures, the chlorophyll a (Chl a) increased across the archipelago by 25 – 40% above its 2004 – 2006 mean and nearly 25% above its 1998 – 2007 mean. The much larger Chl a levels near/within the archipelago as compared to 95° and 110°W implicate that the island platform itself further iron-enriched the upwelling waters.