An Inverse Technique for Obtaining Geostrophic Ocean Currents Independent of Reference Level

Abstract

Wunsch (1977, 1978) has recently applied a discrete form of geophysical inverse theory to the determination of ocean circulation. He estimates the total current by adding a given baroclinic current to a smoothed barotropic current found by conserving mass. The result is, however, fairly strongly dependent on the choice of the reference level used to calculate the baroclinic velocity. In a linear problem such as this, one expects the result to be independent of any starting point. Indeed, Wunsch (1978) gives a procedure which provides a unique answer?he smooths the baroclinic velocity by the same function used to smooth the barotropic. I show that this procedure is a special case of one derivable from a continuous formulation of inverse theory, and that the continuous formulation affords insights not obtainable from the discrete one.