Optimal Estimation of Hydrographic Station Data and Derived Fields

Optimal estimation is applied to contouring and analysis of hydrographic sections. Measured fields, such as temperature and salinity, and derived fields, such as geostrophic velocity, are decomposed into large-scale and small-scale components. First, a heavily sampled basin-scale field is estimated and subtracted from the data. A small-scale field, barely resolved by the hydrography, is then found from the residuals. The power and utility of the technique are illustrated by means of examples, using a short section from the Straits of Florida and a transatlantic section along 24°N.