The Cromwell Current and its effects on the

Galapagos Islands

Jennifer WalkerPhysical Oceanography

Fall 2014

What is the Cromwell Current?

• Discovered in 1951• Last major ocean current to be

found• Cromwell led expedition following

year

General Characteristics

• Geostrophic equilibrium• Symmetrical about equator• 200 m thick• 300 km wide• Velocities up to 1.5 m/s• Core coincides with thermocline• Temp of 13 degrees C

Variations in the current

• Seasonal fluctuations of wind affect transport• Velocity and transport decrease to east• Core depth varies from 50 m in E to 200 m in W• Galapagos is eastern terminus

• Galapagos: 13 islands, 1000 km W of Ecuador• Weakens velocities• Undercurrent splits• Upwelling

The Cromwell Current and the Galapagos Islands

The Current and Galapagos Biology

• Upwelling• High oxygen• High nutrients

• Increased primary production• Effect of El Nino

ReferencesKnauss, J.A., 1997, Introduction to Physical Oceanography, Waveland Press,

Inc., Illinois, 146-151pp.Knauss, J.A., 1961, The Cromwell Current, Scientific American, Inc., 105-119.Liu, Y., L. Xie, J.M. Morrison, D. Kamykowski, and W.V. Sweet, 2014, Ocean

circulation and water mass characteristics around the GalapagosArchipelago simulated by a multiscale nested ocean circulationmodel, International Journal of Oceanography, 2014, 1-16.

Pak, H. and J.R. Zaneveld, 1973, The Cromwell Current on the east side of the Galapagos Islands, Journal of Geophysical Research, 78, 7845-7859.

Philander, S.G., 1973, Equatorial Undercurrent: Measurements and theories, Reviews of Geophysics and Space Physics, 11, 513-570.

Stewart, R., 2002, Introduction to Physical Oceanography, Chapter 14.