The temperature of the top layer of the ocean, measured by satellites, ships and buoys, in °C.
Indices
SST is the temperature of the ocean surface (roughly the top metre). It is measured by satellites (infrared and microwave sensors), ships, drifting buoys and moored buoys such as the TAO array. Products such as NOAA OISST and ERSST blend these into maps.
ENSO is measured mainly with SST in the equatorial Pacific. SST also matters locally: warm water around Samui feeds heavier showers and stresses corals.