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11. Hawaiian lslands, Wakes
This photograph of the Hawaiian islands was taken in June 1983 at the peak of acceleration of the Northern Equatorial Current. These islands are also subjected to the northeast trade winds. Islands in regions of strong current, such as the Hawaiian chain, trail broad wakes that can easily be seen from space, both in the Sun's glitter and in changes of ocean color. The island wake is created by upwelling and vertical mixing induced by current action, which brings deep, cold, nutrient-rich waters near the surface. This increases the phytoplankton concentration and, in turn, ultimately affects surface coloration.
In this photograph, the wakes trailed by Molokai, Lanai, and Kahoolawe are 90 to 140 kilometers in length. The island of Oahu can be seen under cloud cover to the northwest. Early Polynesian navigators may have navigated toward islands beyond the horizon by noting such island wakes and the resultant alteration in sea-surface texture.
STS-7, June 1983. Picture #7-19-0875