Earth is an ocean planet. The oceans cover nearly three-quarters of the world's surface, store most of earth's available heat and carbon dioxide, and play a central role in determining global climate trends. These trends, or climate changes, affect the earth's temperature and rainfall, which in turn impact crops and industry. We study the oceans to understand and possibly predict the effects of their changes.
Throughout history, sailors have measured winds, waves, currents, and tides. Only occasionally would they recognize long-term trends that raised or lowered sea levels. As technology advanced, oceanographers placed precise measuring devices on ships and buoys. This provided a collection of data, which allowed at least a partial look at the changing conditions of the world's oceans.
In recent years scientists have discovered that they can obtain a continuous, comprehensive look at the surface of the world's oceans by using a satellite in space equipped with an instrument called an altimeter.
Building on three earlier earth-orbiting missions TOPEX/Poseidon -- a joint mission between the United States and France -- is part of a global oceanographic effort to acquire a comprehensive look at the world's oceans. TOPEX/Poseidon's contribution involves continuous observation of the surface currents of the ocean.
