What is the Salinity indicator?
The salinity, or saltiness, of the water is shown on this indicator. Oceanographers are interested in salinity because of its traceability. The salinity of a parcel of water won't change unless it mixes with another parcel of water; in Long Island Sound that would include fresh water from the rivers, or ocean waters entering through The Race or Fishers Island Sound. For the most part, you can tell which end of the Sound you are in by looking at the salinty (vertically averaged -- it is saltier at the eastern end than at the western end...). In the open ocean, where mixing processes are much slower - oceanographers can trace parcels of water for large distances and even determine a water parcel's origin. In 1978, the method of measuring salinity was redefined, and is now based on a comparison between electrical conductivity of the sampled water and standard seawater that has a known conductivity. The comparison, which is a ratio, has no units, but for convenience we put pss. Pss stands for Practical Salinity Scale - the official name of the 1978 redefinition. Salinity used to be reported in ppt (parts per thousand) which refers to a concentration of salt, but is no longer valid.
