Study of currents along the Pt.Sur transect in February 1989

Abstract

Ocean currents and density were measured ofT Point Sur, California in February' 1989 using Pegasus (an acoustically tracked velocity profiler), ADCP (a ship-mounted acoustic doppler current profiler), and CTD (conductivity, temperature, depth profiler). Absolute velocities are compared with geostrophy and various flow regimes are analyzed with respect to prominent features and historical and other recent data. Geostrophic cross-sections based on various levels of no motion (L\M) are compared. Temperature, salinity, and density fields are examined and correlated to velocity features. The California Current is a weak ( < 5 cm s) southeastward flow starting about 60 km from the coast. The Davidson Inshore Current is a strong ( > 25 cm/s) surfaceintensified core of warm, fresh water centered 30 km ofishore, and located in the top 100 m. A subsurface maximum of westward flow exists in a well-defined jet 100 m deep about 30 km off Point Sur. There is a trench jet located along the bottom between the continental slope and a seamount 33 km from the coast, which could either be topographically steered out of Monterey Canyon or recirculated from further ofishore. A band of alternating meridional velocity shears is seen in geostrophic sections (based on CTD data) 45-100 km from the coast, not supported by other data, and seems to be located in deep water near the edge of the continental margin. Its position in the water column can be shifted vertically by applying various LNMs, but based on density sections and .'XDCP data it appears to be a feature limited to the water below 1500 m. Otherwise, a 1000 m level of no motion seems to produce the best cross-section of geostrophic velocity.