The Cromwell Current and its effects on the Galapagos Islands Jennifer Walker Physical Oceanography...

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.