Sea level is a measure of the heat stored in the ocean.
In the last month or so, the tropical Pacific has been switching from warm to cold. This change in the winds allows a large mass of warm water that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The change in the wind strength and direction also impacts global weather patterns. This phenomenon was responsible for record rainfall amounts in California, heavy flooding in Peru, drought and wildfires in Indonesia, tornadoes in the southeast United States and loss of life and property damage worldwide. These data are combined with measurements from other instruments that pinpoint the satellite's exact location in space.