Tropical instability wave interactions within the Galapagos Archipelago

The effects of tropical instability waves (TIW) within the eastern equatorial Pacific during the boreal fall of 2005 were observed in multiple data sets. The TIW cause oscillations of the sea surface temperature (SST), meridional currents (V), and 20 degrees C isotherm (thermocline). A particularly strong 3-wave packet of similar to 15-day period TIW passed through the Galapagos Archipelago in Sep and Oct 2005 and their effects were recorded by moored near-surface sensors. Repeat Argo profiles in the archipelago showed that the large temperature ( > 5 degrees C) oscillations that occurred were associated with a vertical adjustment within the water column. Numerical simulations report strong oscillations and upwelling magnitudes of similar to 5.0 m d(-1) near the Tropical Atmosphere Ocean (TAO) buoy at 0 degrees, 95 degrees W and in the Archipelago at 92 degrees W and 90 degrees W. A significant biological response to the TIW passage was observed within the archipelago. Chlorophyll a measured by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) increased by > 30% above 1998-2007 mean concentrations within the central archipelago. The increases coincide with coldest temperatures and the much larger increases within the archipelago as compared to those of 95 degrees W indicate that TIW induced upwelling over the island platform itself brought more iron-enriched upwelling waters into the euphotic zone. Published by Elsevier Ltd.