Sea surface temperature

Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of surface varies in the literature and in practice. It is usually between 1 millimetre (0.04 in) and 20 metres (70 ft) below the sea surface. Sea surface temperatures greatly modify air masses in the Earth's atmosphere within a short distance of the shore. Local areas of heavy snow can form in bands downwind of warm water bodies within an otherwise cold air mass. Warm sea surface temperatures can develop and strengthen cyclones over the ocean. Tropical cyclones can also cause a cool wake. This is due to turbulent mixing of the upper 30 metres (100 ft) of the ocean. Sea surface temperature changes during the day. This is like the air above it, but to a lesser degree. There is less variation in sea surface temperature on breezy days than on calm days. The thermohaline circulation has a major impact on average sea surface temperature throughout most of the world's oceans.^[1]

Coastal SSTs can cause offshore winds to generate upwelling, which can significantly cool or warm nearby landmasses, but shallower waters over a continental shelf are often warmer. Onshore winds can cause a considerable warm-up even in areas where upwelling is fairly constant, such as the northwest coast of South America. Its values are important within numerical weather prediction as the SST influences the atmosphere above, such as in the formation of sea breezes and sea fog.

It is very likely that global mean sea surface temperature increased by 0.88°C between 1850–1900 and 2011–2020 due to global warming, with most of that warming (0.60°C) occurring between 1980 and 2020.^[2]: 1228 The temperatures over land are rising faster than ocean temperatures. This is because the ocean absorbs about 90% of excess heat generated by climate change.^[3]