Abstract

This paper presents a statistical analysis of time series obtained from the Aqualog profiler moored at the upper continental slope off the southeast Russian coast in the northwestern Sea of Japan from mid-April through mid–October 2015. The vertical conductivity, temperature and depth (CTD) profiles with a high resolution (6 hours in time and 1 m in depth) were measured between 64 and 300 m, and the buoyancy frequency was estimated from these data. Buoyancy frequency and temperature data were decomposed to empirical orthogonal functions (EOFs) in the depth-time domain. Fluctuations in the vertical stratification revealed by the buoyancy frequency were assessed and linked to the passage of dynamic structures near the mooring. In the anticyclonic structures, the stratification weakened above 120 m due to isopycnal bending down and strengthened below 165 m. Stratification changes occurred on an 8–13-day timescale due to the passage of mesoscale eddies near the mooring. Energetic fluctuations were also found over longer 20–30- and 80–130-day time scales. These processes were accompanied by temperature anomalies associated with horizontal advection above 150 m and with vertical pycnocline fluctuations in the deeper layer. Temperature anomalies moving in the vertical direction with an average speed of 1.7 × 10^–2 cm/s (14.7 m/day) on timescales from 4 to 13 days were detected at the border between these layers which exhibited different kinds of stratification changes.

中文翻译：

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日本西北海温盐层演化：中尺度变异与年内波动

摘要

本文对 2015 年 4 月中旬至 10 月中旬停泊在日本西北部俄罗斯东南沿海上陆坡上陆坡上的 Aqualog 剖面仪进行了时间序列的统计分析。垂直电导率、温度和深度 (CTD) ) 在 64 到 300 m 之间测量了高分辨率（时间为 6 小时，深度为 1 m）的剖面，并根据这些数据估计了浮力频率。浮力频率和温度数据被分解为深度-时间域中的经验正交函数（EOF）。浮力频率揭示的垂直分层的波动被评估并与系泊附近的动态结构的通过有关。在反气旋结构中，120 m以上由于等密度向下弯曲，分层减弱，165 m以下加强。由于系泊附近的中尺度涡流的通过，分层变化发生在 8-13 天的时间尺度上。在更长的 20-30 天和 80-130 天的时间尺度上也发现了能量波动。这些过程伴随着与 150 m 以上的水平平流相关的温度异常和更深层的垂直密斜波动。温度异常以平均速度 1.7 × 10 垂直方向移动 这些过程伴随着与 150 m 以上的水平平流相关的温度异常和更深层的垂直密斜波动。温度异常以平均速度 1.7 × 10 垂直方向移动 这些过程伴随着与 150 m 以上的水平平流相关的温度异常和更深层的垂直密斜波动。温度异常以平均速度 1.7 × 10 垂直方向移动在 4 到 13 天的时间尺度上，在这些层之间的边界处检测到^–2 cm/s (14.7 m/day)，表现出不同类型的分层变化。