Table of Contents
International Journal of Oceanography
Volume 2014, Article ID 198686, 16 pages
http://dx.doi.org/10.1155/2014/198686
Research Article

Ocean Circulation and Water Mass Characteristics around the Galápagos Archipelago Simulated by a Multiscale Nested Ocean Circulation Model

1Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695-8208, USA
2Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Miami, FL 33129-1098, USA
3Atlantic Oceanographic and Meteorological Laboratory, NOAA, 4301 Rickenbacker Causeway, Miami, FL 33129-1026, USA
4Department of Physics and Physical Oceanography, University of North Carolina at Wilmington, Wilmington, NC 28403-5606, USA
5National Ocean Service, NOAA, Center for Operational Oceanographic Products and Services, Silver Spring, MD 20910-3281, USA

Received 29 September 2013; Accepted 12 December 2013; Published 11 February 2014

Academic Editor: Lakshmi Kantha

Copyright © 2014 Yanyun Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ocean circulation and water mass characteristics around the Galápagos Archipelago are studied using a four-level nested-domain ocean system (HYCOM). The model sensitivity to atmospheric forcing frequency and spatial resolution is examined. Results show, that with prescribed atmospheric forcing, HYCOM can generally simulate the major El Niño events especially the strong 1997-1998 events. Waters surrounding the archipelago show a large range of temperature and salinity in association with four different current systems. West zones of Isabella and Fernandina Islands are the largest upwelling zones, resulting from the collision of the Equatorial Undercurrent (EUC) with the islands, bringing relatively colder, salty waters to the surface and marking the location of the highest biological production. Model results, which agree well with observations, show a seasonal cycle in the transport of the EUC, reaching a maximum during the late spring/early summer and minimum in the late fall. The far northern region is characterized by warmer, fresher water with the greatest mixed layer depth as a result of Panama Current waters entering from the northeast. Water masses over the remainder of the region result from mixing of cool Peru Current waters and upwelled Cold Tongue waters entering from the east.