Characteristic patterns of the circulation in the Santa Barbara Channel
Characteristic patterns of the circulation in the Santa Barbara Channel
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DOI：
10.1029/97jc02393
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发表时间：
1998-02-15
影响因子：
3.6
通讯作者：
Winant, CD
中科院分区：
文献类型：
--
作者：
Harms, S;Winant, CD
根据1993 - 1995年3年期间的观测资料，描述了圣巴巴拉海峡（SEC）和概念点以北陆架的潮下近地表环流。通道中的近表面流是一个大于SBC尺度的流和位于通道内的可变强度的气旋环流的叠加。在季节时间尺度上，表层附近的大于SEC尺度的气流在春季向赤道方向流动，从夏季到冬季向极地方向流动。春季向赤道气流的增加与向赤道风应力的增加以及近地表温度和合成次表层压力（SSP）的降低同时发生。在晚春的流动逆转，同时增加沿通道SSP差异和几个月前风应力已达到峰值。在此期间，在SEC内的气旋性环流是最强的与最强的极向流通过东部入口的时期相吻合。SEC环流的天气学描述是根据六种特征模式提出的，标记为上升流，松弛，气旋，旋转气旋，洪水东，洪水西。将5-m和45-m电流分析为经验正交函数（EOF），将50%（53%）的5-m（45-m）低频电流方差分离为三（2）种模式。将这些模式与平均电流场相结合，这些模式具有与从近地表电流的每日平均值检查中主观推断出的特征流型相对应的空间模式。从春末到秋季，两个最大的5米电流模式产生一个重复的循环模式，其中四个状态（即上升流，气旋，松弛和静止）的顺序，大约每16天遍历一次。除了在SEC中部的大尺度气旋性外，较小的气旋性涡旋经常在东部通道形成，并以0.06 m s（-1）的平均速度向西移动。这里所描述的模式开发响应风应力和沿通道SSP梯度。
The subtidal near-surface circulation in the Santa Barbara Channel (SEC) and on the shelf north of Point Conception is described based on observations obtained during the 3-year period from 1993 to 1995. Near-surface currents in the channel are a superposition of a larger-than-SBC scale flow and a cyclonic circulation of variable intensity located inside the channel. On seasonal timescales the larger-than-SEC scale flow near the surface is equatorward in spring and poleward from summer through winter. The increase in equatorward flow in spring occurs concurrently with the increase in equatorward wind stress and the decrease in near-surface temperatures and synthetic subsurface pressures (SSPs). The flow reverses in late spring, simultaneously with the increase in the along-channel SSP difference and months before wind stress has reached its peak. The period during which the cyclonic circulation within the SEC is strongest coincides with the period of strongest poleward flow through the eastern entrance. A synoptic description of the circulation in the SEC is presented in terms of six characteristic patterns, labeled Upwelling, Relaxation, Cyclonic, Propagating Cyclones, Flood East, and Flood West. An analysis of the 5- and 45-m currents into empirical orthogonal functions (EOFs) isolates 50% (53%) of the 5-m (45-m) low-frequency current variance into three (two) modes. Combining these modes with the mean current fields, the modes have spatial patterns that correspond to the characteristic flow patterns subjectively deduced from inspection of daily averages of the near-surface currents. From late spring through fall the two largest 5-m current modes produce a repeating pattern of circulation in which the sequence of four states (namely, Upwelling, Cyclonic, Relaxation, and Quiescent) is traversed roughly every 16 days. In addition to the large-scale cyclonicity in the central SEC, smaller cyclonic eddies form frequently in the eastern channel and travel toward the west with an average speed of 0.06 m s(-1). The patterns described here develop in response to the wind stress and the along-channel SSP gradient.