Hurricane Floyd's Effect of Shelf Turbidity
Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE
The waters along the Florida/Georgia/Carolina coast in the April 1998 image appear deep blue except for an irregular narrow band along the coast which is colored yellowish-brown by suspended sediments and dissolved, colored organic materials (CDOM) that wash into the ocean from rivers and are resuspended by the action of the surf and currents in the shallow coastal waters. (The lighter blue water further southeast just under the clouds is the Gulf Stream. This water contains less phytoplankton biomass and CDOM than the water nearer shore and therefore scatters more blue light back to the spacecraft.)
In the September 16, 1999 image, the water all the way out to the edge of the continental shelf looks quite bright blue-green. As Hurricane Floyd passed over these waters, he stirred and mixed them much deeper than normal -- deep enough, in this case, to resuspend sediments that had settled on the continental shelf over the years. These resuspended sediments are what give the water its milky green color. A sense of the power of this hurricane is illustrated by realizing that the outer edge of the continental shelf in this area is about two-hundred meters deep.
At the shelf edge the water becomes rapidly deeper and bottom sediment can no longer be reached by the hurricane as you can see in this SeaWiFS image.