Parameter: Sigma_theta

sigma_theta density. [The density calculated with in situ salinity, potential temperature, and pressure = 0, minus 1000 kg/m3. If a pressure reference level other than the surface is used, it will be indicated by using the reference level as the subscript for sigma. When comparing the density of water samples from different depths, it is preferable to use sigma-theta. - added 11/15/2013, njc from the Naval Postgraduate School, http://www.oc.nps.edu/nom/day1/parta.html]