Ocean currents across the entrance to the Gulf of California

Observations of transport and currents in April, May, and December 1992 and January 1993 were made across the entrance to the Gulf of California with an acoustically tracked dropsonde. Flow was into the gulf along Sinaloa and out of the gulf along Baja California. The transports were 5–10 Sv and the currents were deep, with 10 cm s−1 flow extending to depths greater than 1000 m. The currents were intensified in the upper 300 m. Geostrophic flows compared well with observed currents when smoothed to 2–3 times the Rossby radius. Salinity in the upper 300 m was higher on the Baja California side of the gulf, indicating modification of Subtropical Subsurface waters within the Gulf as well as the presence of surface and near‐surface gulf waters. The salinity minimum associated with California Current waters at 50 m had narrow cores that can be resolved only with closely spaced conductivity‐temperature‐depth casts. Mass and heat fluxes for the upper 300 m were estimated as 280 t s−1 and −0.1×1012 W in May and 170 t s−1 and 2.0×1012 W in December.