Equatorial Front in the Eastern Pacific Ocean

Abstract

The equatorial front in the eastern Pacific Ocean observed during 14 October?7 December, 1971, from R/V Yaquina of Oregon State University is discussed. The front is clearly defined at the sea surface by a large horizontal gradient of temperature, salinity, σt and nitrate. Equatorial upwelling, which is believed to be driven by the prevailing wind and the Equatorial Undercurrent, appears as the primary source of the cold water on the south side of the front in the region west of the Galapagos Islands. In vertical distributions of various properties of the water across the equator, equatorial upwelling is apparent over the equator in the region between the Galapagos Islands and the Ecuadorian coast. It is suggested that the equatorial front in this region is also associated with the equatorial upwelling.