The water sampling page explains the analysis on the water samples taken. We do not measure salinity directly, but conductivity is measured instead and can be converted to salinity using mathematical formulae. Temperature Temperature is recorded in degrees Celcius. Higher temperatures are usually found at the sea surface since sunlight and air will warm the water in the summer. During the winter, the air will actually cool the surface layer.
Temperatures generally decrease with depth.
Depth Depth is actually measured as a pressure increase within an fluid-filled diaphram. Each 10 meters increase in depth is approximately equivalent to 1 atmosphere of pressure. Most of our casts are to 500 m, water depth permitting. This instrument measures the clarity of the water by emitting a beam of light at one side and detecting how much of the light is received at the other side. The penetration of light from the surface influences the depth at which phytoplankton and zooplankton exist.