李达, 刘涛, 谢波涛, 等, xxxx. 陆丰海域秋季第一模态内孤立波观测特征分析[J]. 海洋科学进展, x(x): xx-xx. doi: 10.12362/j.issn.1671-6647.20230828002.
引用本文: 李达, 刘涛, 谢波涛, 等, xxxx. 陆丰海域秋季第一模态内孤立波观测特征分析[J]. 海洋科学进展, x(x): xx-xx. doi: 10.12362/j.issn.1671-6647.20230828002.
LI D, LIU T, XIE B T, et al, xxxx. Properties of the first-mode internal solitary waves in autumn over the Lufeng Area in the northern South China Sea revealed by mooring observations[J]. Advances in Marine Science, x(x): xx-xx. DOI: 10.12362/j.issn.1671-6647.20230828002
Citation: LI D, LIU T, XIE B T, et al, xxxx. Properties of the first-mode internal solitary waves in autumn over the Lufeng Area in the northern South China Sea revealed by mooring observations[J]. Advances in Marine Science, x(x): xx-xx. DOI: 10.12362/j.issn.1671-6647.20230828002

陆丰海域秋季第一模态内孤立波观测特征分析

Properties of the First-mode Internal Solitary Waves in Autumn Over the Lufeng Area in the Northern South China Sea Revealed by Mooring Observations

  • 摘要: 南海北部内孤立波异常活跃,具有极强的非线性、极高的强度和极大的能量,其传播特性和精细结构在背景过程影响下更加复杂,加剧了内孤立波预报和海上石油平台作业的难度。基于南海北部陆丰海域295 m水深处一套潜标连续79 d的观测资料,分析了秋季内孤立波的波动特征和统计规律。典型内孤立波表现为波列的形式,头波振幅达86.7 m,在海洋上层导致局地增温超过8.0 ℃,并诱发最大达0.83 m/s的西向流和0.60 m/s的北向流,在波前产生最大达0.25 m/s的下降流。对观测期间捕捉到的91个内孤立波统计分析表明,内孤立波主要沿WNW方向传播,平均振幅为59.9 m,在海洋上层诱发的最强西向流速平均值为0.79 m/s;在04:00至06:00和16:00至19:00以及农历初二至初五和十六至十八期间,内孤立波频繁发生且具有更大的强度。此外,全日内潮与半日内潮共同作用下压了温跃层,导致典型内孤立波中形成了1个上凸波动,其在近底层导致局地降温达1.3 ℃,并诱发超过0.30 m/s的西向流和0.20 m/s的北向流;该上凸波动陡峭的波前汇聚了强剪切,极易触发剪切不稳定。本研究结果可为陆丰海域海上石油平台施工、勘探船作业等提供重要参考。

     

    Abstract: Internal solitary waves (ISWs) in the northern South China Sea are very active, featured by strong nonlinearity, high intensity, and concentrated energy. Their propagation characteristics and fine-scale structures are complicated under the influences of background processes, increasing the difficulties in predicting ISWs and conducting offshore operations on oil platforms. Based on a mooring deployed at a water depth of 295 m over the Lufeng area in the northern South China Sea for 79 days, the properties of and temporal variations in ISWs were carefully analyzed. The typical ISW appeared as wave trains, with a leading wave amplitude of up to 86.7 m, and induced local warming of more than 8.0 °C and the maximum westward and northward currents of up to 0.83 m/s and 0.60 m/s in the upper layer, respectively. The statistical results showed that 91 ISWs captured during the observational periods mainly propagated along the northwest direction, with an average amplitude of 59.9 m and a mean value of the maximum westward currents of 0.79 m/s in the upper layer. Moreover, ISWs occurred frequently and stronger during 04:00-06:00 and 16:00-19:00 and on the 2nd-5th and 16th-19th lunar days. In addition, thermocline depressed by the diurnal and semi-internal tides formed an elevation soliton in the typical ISW, which caused local cooling of 1.3 °C and westward and northward currents of more than 0.3 m/s and 0.2 m/s near the sea bottom, respectively. The steep front of the elevation soliton converged enhanced shear, making it prone to trigger shear instability. This study provides important references for offshore construction on oil platforms and surveying operations over the Lufeng area.

     

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