Mapping Surface Currents in Monterey Bay With CODAR-Type HF Radar

Abstract

HIGH-FREQUENCY (HF) radar measurements have been employed around Monterey Bay, CA, to measure ocean surface currents since February 1992. The first array consisted of two older-generation CODAR instruments located at sites near Monterey in the south and Moss Landing, halfway around the bay to the north (Front Cover: Fig. 1). In 1994, the southern site was replaced with a newer-generation SeaSonde system at Pt. Pinos and a similar unit was installed near Santa Cruz on the northern shore of Monterey Bay. Finally, in 1996, the CODAR system in Moss Landing was replaced by a modern SeaSonde unit. Several months time series of two-dimensional surface currents have been collected for Monterey Bay since the first CODAR units were installed. These data represent the most extensive measurements collected to date from compact, directionfinding HF radar systems (Barrick and Lipa, 1997: Paduan and Graber, 1997). Indeed, Monterey Bay is the only location where continuous HF radar measurements are underway. The geometry of the bay (a curving coastline with a radius of -20 km) is ideal for a multisite HF radar network. The overwater distance is close to the typical radar range and, when three or more shore locations are utilized, the entire region can be observed without lost coverage along the baseline between radar sites. This geometry also makes Monterey Bay well suited for validation and development of the algorithms for currents, waves, and wind direction because a large ocean region is oversampled. Not only can in situ measurements within this region be compared with the remotely sensed estimates, but self-consistency (or lack thereof) in the HF radar measurements can be used to characterize errors in the radar data (Melton, 1995).