Physical Oceanography
VI. Tide and Tidal Currents

Monterey Bay and the central California coast have a mixed mainly semidiurnal tide, with the K1 O1 M2 and S2 constituents contributing about 80% of the total amplitude. The diurnal tidal range is 1.6 m (NOAA 1995). A large fraction of the current variance in Monterey Bay is associated with tidal motions, as shown by Paduan and Neal's (1992) CODAR observations and nearshore current meter records at the site of the Monterey Peninsula Regional Outfall 2 km seaward from the mouth of the Salinas River (Figure 13). The alongshore component of the current meter record was filtered with a low-pass tidal filter. That analysis showed that the non-tidal speeds for November 1976 were less than 10 cm/s (being mostly southerly during this period) and that the high-passed "tidal" velocities were modulated in the characteristic neap-spring cycle. Tidal current speeds were about 20 cm/s during spring tides and about 10 cm/s during neaps. Petruncio's (1993), and Paduan et als. (1995) CODAR method measures currents in the upper 1 m of the water column and reveal that the tidal current ellipses were larger near the head of Monterey Submarine Canyon with speeds of 15 cm/s, and that in the nearshore south Bay currents were strongly aligned with the local bathymetry. These CODAR results promise to shed new light on near surface currents in the Bay and to extend the measurements from the few isolated current meter records to nearly the full areal extent of the Bay.