Strong near-inertial oscillations in geostrophic shear in the northern South China Sea
Strong near-inertial oscillations in geostrophic shear in the northern South China Sea
复制标题
南海北部地转切变的强烈近惯性振荡
DOI：
10.1007/s10872-011-0038-z
复制
发表时间：
2011-07
影响因子：
2.3
通讯作者：
Li CY
中科院分区：
文献类型：
--
作者：
Sun ZY;Hu JY;Zheng QA;Li CY
2008年7月，利用3个声学多普勒海流剖面仪（ADCP）观测资料，在南海北方陆架区发现了强近惯性振荡（NIO）。近惯性流速的幅值远大于全日潮和半日潮的幅值。NIOs的功率在中间层最强，在表层相对较弱，在近底层不显著。频谱分析表明，NIO的峰值频率为0.0307 cph，比本地惯性频率低2%，即，红移近惯性波具有向上的垂直相速度，其中包括向下的群速度和能量通量。估计的垂直相速度约为43 m day-1，对应的垂直波长约为58 m。NIOs的水平尺度至少为数百公里。这次NIO事件在台风经过后持续了约15天。在东北方向的背景气流中存在明显的水平切变，多普勒频移和切变流调制机制都可能是造成NIO红移的原因。对于切变流机制，观测到的负背景涡度和相应的有效Coriolis频率降低了NIO的容许频带下限，导致了红移。同时，具有加宽频带的系泊区域充当波导。俘获效应和放大效应导致观测到的NIO持续时间较长。
With observational data from three Acoustic Doppler Current Profiler (ADCP) moorings, we detected strong near-inertial oscillations (NIO) in the continental shelf region of the northern South China Sea in July 2008. The amplitude of the near-inertial current velocity is much greater than that of diurnal and semi-diurnal tides. The power of the NIOs is strongest in the intermediate layer, relatively weak in the surface layer, and insignificant in the near-bottom layer. The spectral analysis indicates that the NIOs have a peak frequency of 0.0307 cph, which is 2% lower than the local inertial frequency, i.e., a red-shift. The near-inertial wave has an upward vertical phase velocity, which involves a downward group velocity and energy flux. The estimated vertical phase velocity is about 43 m day−1, corresponding to a vertical wave length of about 58 m. The horizontal scale of the NIOs is at least hundreds of kilometers. This NIO event lasted for about 15 days after a typhoon’s passage. Given the northeastward background flow with significant horizontal shear, both Doppler shift and shear flow modulation mechanisms may be responsible for the red-shift of the observed NIOs. For the shear flow mechanism, the observed negative background vorticity and the corresponding effective Coriolis frequency reduce the lower limit of admissible frequency band for the NIOs, causing the red-shift. Meanwhile, the mooring area with the broadened frequency band acts as a wave-guide. The trapping and amplification effects lead to the relatively long sustaining period of the observed NIOs.
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影响因子：
25.2
作者：
F. Webster
通讯作者：
F. Webster
影响因子：
--
作者：
Xin‐Zhong Liang;Xiaoqian Zhang;Jiwei Tian
通讯作者：
Xin‐Zhong Liang;Xiaoqian Zhang;Jiwei Tian
影响因子：
3.5
作者：
E. Kunze
通讯作者：
E. Kunze
DOI：
10.1016/0011-7471(72)90022-8
发表时间：
1970-06
期刊：
Deep Sea Research and Oceanographic Abstracts
影响因子：
--
作者：
H. Perkins
通讯作者：
H. Perkins
DOI：
10.1016/0011-7471(76)90879-2
发表时间：
1976-11
期刊：
Deep Sea Research and Oceanographic Abstracts
影响因子：
--
作者：
H. Perkins
通讯作者：
H. Perkins