Satellites can measure water temperature to an accuracy better than 0.5 degrees Celcius. That's extremely accurate for an instrument that sees the Earth's surface from an altitude of approximately 800 km. The smallest spatial resolution (pixel size) that the AVHRR instrument sees on the Earth's surface is approximately 1.1 km.

Knowing the water temperature is important for many reasons. Living resources and ecological processes depend on the water to be in a particular range. If the water is too hot, the fish and other marine organisms will suffer stress, and may not be as productive. Also, changes in temperature over an extended period may cause some organisms to move to other regions where the temperature is more favorable for them, and may cause other non-native organisms to move into the region, thereby bringing about undesirable changes for certain human livelihoods such as fishing.