基于潜标观测的黑潮-亲潮混合区近惯性能量季节变化特征研究

近惯性内波广泛存在于全球海洋,是维持深层海洋跨等密度面湍流混合及海洋层结的重要能量来源。基于黑潮-亲潮混合区的多年深海潜标数据, 分析了: (1) 该海域近惯性内波及其能量的季节变化特征与影响因素, (2) 上层和深层近惯性运动的频率、波数谱及垂向分布等特征。结果表明, 该海域存在丰富的近惯性动能, 无论海洋上层还是深层均呈现显著的冬季强、夏季弱的季节变化特征, 冬季(12~2月)上层的近惯性能量可占全年能量的41%, 深层近惯性信号同样显著, 同潮汐信号相当。平板模型分析表明, 该区域近惯性动能的季节循环特征主要受风场的季节变化所主导,同时受到黑潮延伸体流轴的摆动调制。

CHARACTERIZATION OF SEASONAL VARIATION OF NEAR-INERTIAL ENERGY IN KUROSHIO-OYASHIO MIXED ZONE BASED ON MOORING OBSERVATIONS

Near-inertial waves (NIWs) are widespread in the global ocean, and are a significant energy source for turbulent diapycnal mixing in the deep ocean to maintain ocean stratification. Based on multi-year deep-sea mooring data collected in the Kuroshio-Oyashio mixed zone, we focused on the seasonal variations and the dominant factors in determining near-inertial kinematic energy in this region, and the characteristics of wave frequency, wavenumber spectrum, and vertical distribution of near-inertial motions in the upper and deep ocean. Results revealed the presence of abundant near-inertial kinetic energy in this region. Both the upper and deep ocean layers exhibit notable seasonal variation, and are characterized by pronounced intensification in winter and weakening in summer. Specifically, in winter months, near-inertial energy in the upper layer can contribute to 41% of the total annual energy. Moreover, the near-inertial energy in the deep-layer ocean is equally significant, being comparable to the tidal signals. The slab model suggests that these seasonal cycles of near-inertial energy are primarily driven by external wind forcing, with additional influence from the northward shift of the Kuroshio extension axis.