Watchers in the Sky: Observing Ocean Color from Space
Ocean color depends on the amount of phytoplankton in the water.
Green water = More phytoplankton
From a ship we could observe ocean color in different parts of the ocean, and figure out how much phytoplankton there is. But the ocean is HUGE! From a ship or even an aircraft we can observe only a tiny fraction of the ocean at one time.
From a satellite orbiting a few hundred kilometers above the Earth, we can see all of the oceans in just a few hours!
A special device on the satellite, called a sensor , makes a very accurate color image of the oceans, and sends the data back to the Earth. From this data, scientists figure out how much phytoplankton is in different parts of the image.
Here are some ocean color images .