Subtidal velocity correlation scales on the northern California shelf

Along‐ and cross‐shelf correlation scales of subtidal cross‐shelf ( u ) and along‐shelf ( v ) velocities are estimated using moored records from several field programs over the northern California shelf. Over record lengths of 4–6 months, along‐shelf correlation scales of v are greater than maximum mooring separations (60 km). In the cross‐shelf direction, v is generally correlated between the 60 and 130 m isobaths (10–15 km separation). Along‐shelf correlation scales of u are much smaller than those of v and are often not resolved by minimum mooring separations. Time series between November 1988 and May 1989 do resolve along‐shelf correlation scales of near‐surface u and indicate that they are 15–20 km. During this time the along‐shelf correlation scale of near‐surface u shows variability on a monthly scale. It is generally long (30 km or more) when correlation of u with wind stress is high and short (15 km or less) when correlation with wind stress is low. On at least one occasion, short along‐shelf correlation scales coincide with the intrusion of an offshore mesoscale feature onto the shelf. Cross‐shelf correlation scales of u are resolved for typical mooring separations. In general, u is correlated between the 90 and 130 m isobaths (7–13 km separation) and between the 60 and 90 m isobaths (∼5 km).