| 摘要: |
| 本研究通过OW（Okubo-Weiss）参数和闭合等值线相结合的方法自动识别西北太平洋（0°—45°N，120°—180°E）中尺度涡并跟踪后续中尺度涡，分析了不同寿命中尺度涡的季节变化、年际变化、数量特征以及动力学参数等。研究发现，不同寿命中尺度涡的数量高峰时间在不同程度上晚于气象上最冷月份约1~3个月。与其他寿命中尺度涡不同，中等寿命中尺度涡的气旋涡（33.9 cm/s）比中等寿命中尺度涡的反气旋涡（16.9 cm/s）旋转得更快，季节变化最为显著。冬季更适于西北太平洋中尺度涡的发生与发展，并且在寿命上，更易发展为中等寿命涡旋。不同寿命中尺度涡的月数量变化都存在3个明显的周期性变化（第一主周期、第二主周期、第三主周期），根据不同主周期的时间尺度长短，它们的影响因子分别可能是太阳辐射、ENSO现象、季节变化。从地理分布看，不同寿命中尺度涡高频区分布并不完全一致。从涡旋平均振幅地理分布看，中等寿命中尺度涡在高频区拥有最大的涡旋平均振幅（15~25 cm），短寿命中尺度涡次之（15~20 cm），长寿命中尺度涡的平均振幅最小（10~16 cm）。从涡旋半径地理分布看，长寿命中尺度涡仅在副热带逆流区有较大的平均半径（20~30 km），中等、短寿命中尺度涡在研究区域北部均有着较大的平均半径（30~45 km）。从动力学参数看，西北太平洋中尺度涡的动力学参数在寿命中期并非是最高值，约在寿命的前三分之一达到第一个高值，然后小幅下降，保持稳定，直到寿命的后三分之一小幅上升，达到第二个高值，然后迅速下降直至数值为零。 |
| 关键词: 海洋物理学 中尺度涡旋 寿命 统计特征 西北太平洋 |
| DOI：10.3969/J.ISSN.2095-4972.2023.02.011 |
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| 基金项目:山东省重点研发计划（2019JZZY020713）；辽宁省教育厅项目（QL201905，DL202001，JL202006，QL202006）；辽宁省博士科研启动计划（2021-BS-239）；大连市高层次人才创新支持计划（2020RQ113） |
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| Statistical characteristics of different lifetime mesoscale eddies in the Northwest Pacific Ocean by reanalyzed data |
| LUO Na,SONG Jun,GUO Junru,WANG Linhui,WANG Xifeng,FU Yanzhao |
| (College of Marine Science and Environment, Dalian Ocean University, Dalian 116023, China;Institute of Applied Oceanography, Dalian Ocean University, Dalian 116023, China) |
| Abstract: |
| In this paper, the mesoscale eddies in the Northwest Pacific Ocean (0°—45°N, 120°—180°E) are automatically identified and followed by the method of OW parameter and closed curve. The seasonal variation, interannual variation, quantitative characteristics and geometric parameters of mesoscale eddies with different lifetime are analyzed. It is found that the peak of the number of short lifetime (15-30 days) and medium lifetime (30-105 days) mesoscale eddies is about 2-3 months later than the cold peak of the meteorological season. Different from other lifetime mesoscale eddies, for the medium lifetime mesoscale eddies, cyclonic eddies (33.9 cm/s) rotates faster than the anticyclonic eddies (16.9 cm/s), and medium lifetime mesoscale eddies’ seasonal variation is the most significant. Winter is more suitable for the occurrence and development of mesoscale eddies in the Northwest Pacific Ocean, and in terms of lifetime, it is more likely to develop into medium lifetime eddies. There are three obvious periodic changes (the first main cycle, the second main cycle and the third main cycle) in the monthly number changes in mesoscale eddies of different lifetimes. According to the time scale of different main cycles, their influencing factors may be sunspot activity, ENSO phenomenon and seasonal variation respectively. In terms of geographical distribution, the distribution of high frequency of mesoscale eddies with different lifetimes is not completely consistent. In terms of eddy’s amplitude, the medium lifetime mesoscale eddies have the largest amplitude (15-25 cm), followed by the short lifetime mesoscale eddies (15-20 cm), and the long lifetime mesoscale eddies has the smallest amplitude (10-16 cm). In terms of eddy’s radius, the average radius of long lifetime mesoscale eddies is bigger (20-30 km) only in the subtropical countercurrent area, whereas the average radius of medium and short lifetime mesoscale eddies is bigger (30-45 km) in the north of the study area. From the geometric parameters, the mesoscale eddies’ geometric parameter of Northwest Pacific Ocean is not the biggest in the middle of life. It reaches its first high value about the first third of its life, and then fell slightly, maintaining a stable value, until it rises slightly to the second high value in the last third of life, and then fell rapidly to zero. |
| Key words: physical oceanography mesoscale eddies lifetime statistical characteristics Northwest Pacific |
