Objective Estimation of Velocity Streamfunction Field with Discretely Sampled Oceanic Data I : with Application of Helmholtz Theorem

An objective method for the generation of velocity streamfunction is presented for dealing with discretely sampled oceanic data. The method treats a Poisson equation (forced by vorticity) derived from Helmholtz theorem in which streamfunction is obtained by isolating the non-divergent part of the two-dimensional flow field. With a mixed boundary condition and vorticity field estimated from observed field, the method is implemented over the Texas-Louisiana shelf based on the current meter data of the Texas-Louisiana Shelf Circulation and Transport Processes Study (LATEX) measured at 31 moorings for 32 months (April 1992 - November 1994). The resulting streamfunction pattern is quite consistent with observations. The streamfunction field by this method presents an opportunity to initialize and to verify computer models for local forecasts of environmental flow conditions for oil spill, nutrient and plankton transports as well as opportunity to understand shelf-wide low-frequency currents.