Seasonal and Interannual Variations of Sea Temperature Influenced by Galapagos Islands in Eastern Tropical Pacific Ocean

The sea surface temperature and surface currents during 1993-2016 based on satellite remote sensing, along with the ocean temperature and currents during 1993-2013 from a data assimilative ocean simulation product, are analyzed to investigate the influence of the Galapagos Islands (GI) in the eastern tropical Pacific on the sea surface temperature. Variations of the cold core west of the GI are quantified by T-C-T-W, T-C-T-E, and the cold core area (CCA), where T-W, T-C, and T-E are the sea surface temperature to the west of the cold core, in the cold core, and to the east of the GI, respectively. T-C-T-E and the CCA show a stronger influence of the GI in boreal fall than in spring, in contrast to T-C-T-W, which shows a stronger influence in spring than in fall. All three indices show weaker (stronger) GI's influence during El Nino (La Nina) years, but only CCA and T-C-T-E have significant correlations of -0.66 and 0.61 with the Nino3 index. Variations of T-C-T-W are related to that of upwelling immediately the west of the GI. Variations of T-C-T-E and CCA are related to that of the spatial distributions of the upper ocean temperature, the advection of temperature by the horizontal currents, specifically the north branch of the South Equatorial Current, and upwelling in the eastern tropical Pacific.