基于观测的南海西沙海域深层近惯性振荡特征分析

近惯性内波运动普遍存在于全球大洋中,影响大洋中的质量、动量和能量输送,是大气强迫与海洋混合之间的重要纽带。由于目前海洋深层观测资料的缺乏,对于深层近惯性内波生消演变特征研究甚少。利用2009-2012年的潜标观测资料,采用带通滤波和谱分析方法研究了南海西沙海域深层近惯性内波生成、传播和消亡等演变特征。通过研究发现,南海西沙海域深层存在较强的近惯性振荡,其生成源为台风过境能量输入,绝大部分时段内,近惯性振荡能量在海洋浅层耗散,不向海洋深层传播;仅在少部分时段内,近惯性振荡能量的80%～85%耗散在500 m以浅区域,有大概15%～20%继续向海洋深层传播。

Evolvement analyses of near-inertial motion in deep oceans by submarine observations of Xisha Island in the South China Sea

Near-inertial motion which is ubiquitous in the global ocean affects the mass momentum and energy transport,and it is an important connection between atmospheric forcing and ocean mixing. Due to the lack of deep ocean observation,the generation and disappearance ofnear-inertial motion has rarely been researched in deep oceans. Based on the submarine observation data from 2009 to 2012, the evolution characteristics of deep near-inertial motions in Xisha Island of the South China Sea were analyzed by band -pass filtering and spectral analysis. It is found that there are strong near -inertial oscillations in the deep layer of Xisha Island waters,which are generated by the energy input of typhoon. In most periods,near-inertial motion energy dissipates in the shallow layer of the ocean and does not propagate to the deep layer of the ocean.Only in a few cases, 80 % to 85 % of near-inertial motion energy dissipates in the layer shallower than 500 m, and 15 % to 20 % could propagate into deep oceans.