The Occurrence, Variability, and Potential Drivers of Submesoscale Eddies in the Southern California Bight Based on a Decade of High‐Frequency Radar Observations
The Occurrence, Variability, and Potential Drivers of Submesoscale Eddies in the Southern California Bight Based on a Decade of High‐Frequency Radar Observations
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DOI：
10.1029/2023jc019914
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发表时间：
2023-10
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影响因子：
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通讯作者：
A. R. Payandeh;L. Washburn;B. Emery;J. Ohlmann
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文献类型：
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作者：
A. R. Payandeh;L. Washburn;B. Emery;J. Ohlmann
亚中尺度涡旋是南加州低气压（SCB）环流的重要组成部分。尽管亚中尺度涡旋在影响海洋物理、生物和生态过程方面具有公认的重要意义，但由于现场和远程平台带来的技术挑战，研究和观察亚中尺度涡旋一直非常困难。本文利用近十年的高频雷达地面流观测资料，描述了南海的亚中尺度涡旋。从2012年到2021年，共检测到约23.5万个漩涡，平均每周452±116个漩涡。随着时间的推移，在某些地方反复出现的漩涡形成了漩涡活动的热点，主要与地形特征有关。在季节尺度上，夏季和初秋涡旋较多。在年际尺度上，与2014-2015年海洋热浪和2015-2016年厄尔尼诺现象Niño相关的涡旋计数增加了40%。在涡旋和归一化涡度的形成过程中观察到一个全域的日循环。为了确定潮汐和日风的相对贡献，对SCB的光谱成分及其空间分布进行了分析。结果表明，虽然日潮对日变化有一定的影响，但与日风相比，日潮的影响相对较小。这一结论是通过考虑S1频率的普遍性得出的，S1频率是一种已知与海陆微风引起的运动有关的气象潮汐。总体而言，SCB南部的日变率更为显著，而北部的日变率则不那么显著。
Submesoscale eddies form an important component of the circulation of the Southern California Bight (SCB). Despite their acknowledged significance in influencing ocean physics, biology, and ecological processes, submesoscale eddies have been exceptionally hard to study and observe because of the technical challenges posed by both field and remote platforms. Here, using a decade of high‐frequency radar surface current observations, we describe submesoscale eddies in the SCB. Between 2012 and 2021, a total of ∼235,000 eddies were detected, averaging 452 ± 116 eddies per week. Recurring eddies in certain locations over time, formed hotspots of eddy activity, largely in association with topographical features. On seasonal scales, eddies were more numerous in the summer and early fall. At inter‐annual scales, eddy counts increased by 40% in association with the 2014–2015 marine heatwave and the 2015–2016 El Niño. A domain‐wide diurnal cycle was observed in the formation of eddies and the normalized vorticity. To determine the relative contributions of tides and diurnal winds, an analysis of spectral components and their spatial distribution along the SCB was conducted. The results revealed that while diurnal tides may exert some influence on the diurnal variations, their effect is comparatively minor when compared to diurnal winds. This conclusion was reached by considering the prevalence of the S1 frequency, which is a meteorological tide known to be associated with motions induced by sea‐land breeze. Overall, diurnal variability was more prominent in the southern SCB and less significant toward the north.