The Borderland Basins off Southern California are
semi-isolated sea-floor depressions with connections to each other
and to the open Pacific Ocean over narrow sills. A high-resolution,
multi-year simulation is analyzed for its currents, stratification,
and dissolved oxygen, with a focus on the mean conditions, intrinsic
variability, and exchange rates with surrounding waters. The three
shallowest, closest basins are given the most attention: Santa
Barbara, Santa Monica, and San Pedro. From a combination of
multiple means of estimation, the deep basin water mass renewal
times are on the order of a year or more, and this time is somewhat
shorter in the Santa Barbara Basin than the others.