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.
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