If the upward flow of nutrients is interrupted, the same expanse will soon lose its greenish hue as the warming, infertile waters become incapable of supporting much life. Near the poles oceans are often white from a cover of ice and snow. Along coasts sediment from rivers and floods can turn the water a muddy brown. Vast dust storms spin out over the Atlantic from the Sahara and over the Pacific from central Asia. In bays, the ominous spread of a red tide can be deadly for fish and harmful to humans as well.
Oil is spilled.
The human hand leaves fingerprints of pollution. All of these variables are reflected in ocean color. But often these variations occur at such a large scale it is difficult to study them based on surface observations. Over the past two years, SeaWiFS has been serving up a feast of spectacular images and data. As its capabilities have become more widely recognized SeaWiFS' gaze is being turned toward the earth's landmasses and atmosphere as well.