TOPEX/Poseidon continually maps changes in sea level due to heat storage in the ocean. The observations are valuable because changes in heat stored in the ocean affects our global climate. This information can help scientists predict climate changes, and possibly help avert the ill-effects that might occur from extreme weather conditions.
The upper three meters of the ocean store the same amount of heat as does the entire atmosphere. This heat is released and reabsorbed regularly in a cycle from ocean to atmosphere and back. Since unusual patterns in the rate and size of this exchange can cause severe weather, oceanographers measure the oceans' temperature to see if they can identify and predict such patterns.
In addition to affecting the weather, changes in ocean temperature affect sea-level. The majority of sea-level rise is due to thermal expansion. As ocean temperature rises, the water expands to occupy more space. The melting of polar ice has an additional but more minor effect.
In the past, scientists had to rely on tide gauges and other devices to measure change in sea level. Now we have TOPEX/Poseidon giving us half a million observations in just one 10-day cycle.
