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

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

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。

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.