Studies of spatial and temporal surface current turbulence outside Golden Gate

This contribution examines the zero-mean random variability of surface currents seen by drifters and HF radar outside of Golden Gate in the Pacific. Seeding multiple drifters within cells of radar spatial and temporal scale sizes allows an understanding of this natural variability. Using the drifter velocity standard deviations to establish these turbulent motions is important in assessing radar errors, as it allows apportioning the differences between natural surface motions (that may not be of interest in studying mean flows) and radar noise. Numbers obtained in this study are about 4.1 cm/s for spatial and 1.2 cm/s for temporal drifter standard deviations, respectively. Similar numbers for radar standard deviations are 8.2 and 3.2 cm/s. RMS differences between radar and drifter radial velocities here are typically 8-9 cm/s.