MINIMAL ADJUSTMENT OF HYDROGRAPHIC PROFILES TO ACHIEVE STATIC STABILITY

Hydrographic data, be it raw or highly averaged observational data, co ntain substantial regions having vertical density inversions. An algor ithm is described that minimally modifies such data so that the result ing hydrographic casts have vertical buoyancy frequency profiles large r than a specified lower bound. The method underlying the algorithm is based on the solution of a constrained weighted least-squares problem and maximizes the smoothness of the resulting salinity-potential temp erature diagram. Examples are provided that demonstrate the effectiven ess of the technique in minimally altering hydrographic data only in t he immediate vicinity of the data that do not already satisfy the buoy ancy frequency constraint. A modified equation of state, identical in form to the international equation of state of seawater but written in terms of potential rather than in situ temperature, is also provided, enabling rapid computation of the thermal expansion and saline contra ction coefficients.