By using information about the temperature and salinity of ocean water, oceanographers can determine the

By using information about the temperature and salinity of ocean water, oceanographers can determine the: Density

By using salinity, the oceanographer could determine to pick up the ocean water (let say for about 1 litre) and let it evaporate from the temperature.  This will leave them with the amount of salt per liter and its salt ratio could be used to determine the density for the ocean.