ESTIMATES OF HORIZONTAL DIVERGENCE AND VERTICAL VELOCITY IN THE EQUATORIAL PACIFIC

Horizontal divergence and vertical velocity in the surface mixed layer of the equatorial Pacific between 90-degrees and 150-degrees-W are es timated from current measurements obtained from trajectories of freely drifting buoys during 1979-1990. The 12-year averaged horizontal dive rgence is predominantly meridional and has a maximum magnitude of 3-4 (X 10(-6) s-1) in a 20-km-wide latitude band centered on the equator. Using the equation of continuity, this divergence corresponds to an up welling velocity of 1.5-2 (x 10(-4) m s-1) at 50-m depth. The seasonal variations of equatorial divergence are in good agreement with the lo cal zonal wind stress.