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. Below the basin sill depths, the water masses in the basins are distinct from surrounding waters at the same density indicating a degree of dynamical isolation. The mean circulations are anti-clockwise around the topographic edges of the basins, consistent with eddy-driven flows (i.e., topostrophy). The mesoscale eddy variability is stronger than the mean flow, and at least partially it is comprised of topographic Rossby waves circuiting the edge slopes. Its magnitude is similar to the high-frequency currents (mostly tidal). There are recurrent cross-sill flows driven by an unbalanced pressure-gradient force, and these intermittently cause water mass flushing of the basins. The oxygen levels in the basins are occasionally anoxic, and they are maintained by a balance of downward physical transport from above, local respiration, and flux into the sediments. 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. The renewal processes are by intermittent sill overflows and by vertical exchanges through eddies and tides.

中文翻译：

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加利福尼亚州边境盆地的循环和扩散


南加州附近的边境盆地是半孤立的海底洼地，彼此相连，并通过狭窄的岩台与开阔的太平洋相连。高分辨率、多年模拟分析了水流、分层和溶解氧，重点关注平均条件、内在变异性以及与周围水域的汇率。最受关注的是三个最浅、最近的盆地：圣巴巴拉、圣莫尼卡和圣佩德罗。在盆地基台深度以下，盆地中的水团与周围相同密度的水域不同，表明一定程度的动力隔离。平均环流围绕盆地地形边缘呈逆时针方向，与涡流驱动的流动（即地形）一致。中尺度涡流变化比平均流强，并且至少部分由环绕边缘斜坡的地形罗斯贝波组成。其强度与高频电流（主要是潮汐）相似。在不平衡的压力梯度力的驱动下，存在周期性的跨台流，这些间歇性地导致水团冲刷盆地。盆地中的氧气水平偶尔会缺氧，它们是通过从上方向下的物理传输、局部呼吸和进入沉积物的通量的平衡来维持的。综合多种手段估算，深盆地水体更新时间在一年甚至更长的数量级，而圣巴巴拉盆地的更新时间较其他盆地要短一些。更新过程是通过间歇性的窗台溢流以及通过涡流和潮汐的垂直交换来实现的。