Local and remote forcing of currents and temperature in the central Southern California Bight
Local and remote forcing of currents and temperature in the central Southern California Bight
复制标题
南加州湾中部洋流和温度的本地和远程强迫
DOI：
10.1029/2000jc000313
复制
发表时间：
2003
影响因子：
--
通讯作者：
S. Allen
中科院分区：
文献类型：
--
作者：
B. Hickey;E. Dobbins;S. Allen
[1]对南加州湾中部的综合研究表明，潮下流主要由相对较长的时间尺度（10-25天）、大的沿岸尺度和显著的离岸和向上传播相控制。一维模型显示，观测到的波动、向极地传播（速度140-260 cm s−1）的沿岸压力梯度扰动比当地风应力（两个季节至少40%）占沿岸速度方差的比例大得多，并且具有较长的主导电流周期。随着当地风应力的增加，大约一半的速度方差可以解释，总的来说，大约5%的方差在春季比夏季。结果是一致的远程风应力产生的干扰几百公里赤道的海湾和alongcoast传播的低模式沿海被困波。大规模的远程强迫也负责相邻的货架上的速度变化，半封闭的圣莫尼卡湾。一个非线性的三维模型表明，水被推入海湾最初作为一个通流的一部分，后来成为一个漩涡，逐渐填补海湾，产生逆流的岸边。在陆架上，沿岸风应力在春季仅占速度方差的25%，而在夏季几乎不占。大规模的扰动也产生显着的温度波动，整个区域，通过横向平流的平均沿岸温度梯度。在春季的几个2-4天的事件中，当地风驱动的海岸上升流是内陆架温度波动的原因，但仅在海岸壁附近。
[1] A comprehensive study of the central Southern California Bight shows that subtidal currents are dominated by relatively long time scales (10–25 days), large alongshore scales, and significant offshore and upward phase propagation. A one-dimensional model shows that observed fluctuating, poleward propagating (speeds 140–260 cm s−1) alongshore pressure gradient disturbances account for a much larger fraction of the alongshore velocity variance than local wind stress (at least 40% in both seasons) and have the longer periods of the dominant currents. With the addition of local wind stress, about half the velocity variance can be accounted for, and overall, about 5% more variance in spring than in summer. Results are consistent with generation of disturbances by remote wind stress several hundred kilometers equatorward of the bight and alongcoast propagation as low-mode coastally trapped waves. The large-scale remote forcing is also responsible for much of the velocity variance on the adjacent shelf, the semienclosed Santa Monica Bay. A nonlinear, three-dimensional model shows that water is pushed into the bay initially as part of a throughflow, later becoming an eddy that gradually fills the bay, producing counterflow on its shoreward side. On the shelf, local alongshore wind stress accounts for only 25% of the velocity variance in spring and none in summer. The large-scale disturbances also produce significant temperature fluctuations throughout the region, via lateral advection of the mean alongshore temperature gradient. Local wind-driven coastal upwelling is responsible for temperature fluctuations on the inner shelf during several 2–4 day events in spring, but only very near the coastal wall.