1. When wind-driven surface currents carry water away from continents, an upwelling of deep ocean water occurs. These cold waters have high concentrations of nutrients, leading to phytoplankton growth and creating a highly productive fishing area. Ocean plants live within 200 meters from the surface where there is sunlight.

2. Most zooplankton migrate to the surface at night to feed on phytoplankton, and then sink to greater depths during the day. When zooplankton die, they carry carbon with them as they sink to the bottom of the ocean.

3. Plants and bacteria are at the bottom of the food chain. Animals that eat grass, such as sheep, belong to higher food web levels.

4. A polar-orbiting satellite potentially can "see" everywhere in the world in about two days, and its orbit is low enough so that it can detect smaller details than a geostationary satellite. lt will pass over a certain area once daily at the same time of day, which is important for instruments that use sun illumination for measurements of ocean color or land vegetation. A geostationary orbit can view almost an entire hemisphere at the same time, is able to track hurricanes and Weather systems by making measurements every half hour or so, and also is used for meteorological purposes.

5. Differences in the heating and cooling rates of land and ocean affect air circulation. Land and water temperatures rise and fall at different rates because land absorbs and loses heat faster than water does. During the day, hot air rises and is replaced by cooler air. This small-scale circulation is called a sea breeze, and usually starts three or four hours after sunrise, reaching its peak by early afternoon. At night, the land is cooler than the water because the land has given up its heat to the atmosphere. The cool air flows over the warmer water and rises as it is warmed. This circulation is called a land breeze, and usually starts to form in the late evening. lt reaches its peak intensity near sunrise.

6. Global warming may cause sea levels to rise by several mechanisms. Temperature increases may cause some of the ice in the polar regions to melt, which would raise sea levels. Higher water temperatures also may cause the oceans to expand. This expansion would cause a sea-level rise. Scientists are studying how global warming would affect sea levels, because a substantial rise in the sea level may flood coastal cities and other low-lying areas.

7. Plankton (microscopic drifting plants and animals) live near the ocean surface where there is sunlight. Satellites will see changes in the color of water that indicates growth of ocean plants.

SeaWiFS Teacher's Guide and Activities
gene carl feldman (301) 286-9428