Why Scientists Measure the Temperature of the Sea's Surface

The ocean covers 71 percent of Earth's surface, and the temperature of its topmost layer is one of the most important numbers in climate science. Sea surface temperature (SST) is how scientists understand the way the ocean communicates with the atmosphere, and it provides fundamental information about the global climate system.

A simulation of sea surface temperatures from NOAA's Geophysical Fluid Dynamics Laboratory. The model inspired a U.S. Postal Service Forever international rate stamp, released on Earth Day in 2014. Credit: NOAA.

Spotting El Niño and La Niña

SST data is especially useful for detecting the start of El Niño and La Niña cycles. During El Niño, the Pacific near the equator is warmer than normal; during La Niña, the same area is colder than normal. These cycles are caused by multiyear shifts in pressure and wind speed, and they affect ocean circulation, weather patterns around the globe, and marine ecosystems.

What else it is used for

SST is essential to weather prediction and to atmospheric model simulations, and it matters for studying marine ecosystems. It also serves a wide range of practical uses:

• climate and seasonal monitoring and forecasting
• military defense operations
• checking atmospheric models
• tracking sea turtles
• assessing coral bleaching
• tourism
• managing commercial fisheries

How it is measured

Scientists measure SST with temperature sensors on satellites, buoys, ships and ocean reference stations, and through marine telemetry. The NOAA-led U.S. Integrated Ocean Observing System and NOAA's Center for Satellite Applications and Research combine their data to provide sea surface temperatures worldwide.

Sources

Based on "Why do scientists measure sea surface temperature?" from NOAA's National Ocean Service, a work of the United States government in the public domain.