APPLICATION OF THE ADJOINT TECHNIQUE TO PROCESSING OF A STANDARD SECTION DATA SET - WORLD OCEAN CIRCULATION EXPERIMENT SECTION S4 ALONG 67-DEGREES-S IN THE PACIFIC-OCEAN

We present a variational data assimilation scheme designed to recover the steady state of an ocean region along a conductivity-temperature-d epth section track. Oceanic velocity and tracer fields are assumed to satisfy simple stationary dynamical constraints, which include the equ ation of state of seawater, a dynamical constraint on vertical velocit y, stationary tracer transfer equations, geostrophic relations for hor izontal velocities, and the kinematic constraint, imposed on the net t ransport across the section plane. Cousin data assimilation experiment s with the steady state geostrophic component of the fine resolution a ntarctic model have shown that in addition to the absolute cross-secti on velocity component and along-section gradients of properties, the a lgorithm is capable of reconstructing the cross-section gradients of t emperature, salinity, and along-section velocity component. The algori thm can also process an arbitrary set of passive tracer fields measure d at the section. These fields are coupled statistically with active t racers and between each other via the depth dependent in situ covarian ce matrix. Error analysis of the assimilated data set taken at 67 degr ees S in the southern Pacific has shown that the major state vector co mponents were statistically reliable.