| 南海西北部上层海洋对台风“杜苏芮”的响应分析 |
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| 引用本文： | 张骞,廖光洪,蔺飞龙,金魏芳,梁楚进.南海西北部上层海洋对台风“杜苏芮”的响应分析[J].海洋学报,2019,41(7):22-35. |
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| 作者姓名： | 张骞 廖光洪 蔺飞龙 金魏芳 梁楚进 |
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| 作者单位： | 1.自然资源部第二海洋研究所 卫星海洋环境动力学国家重点实验室，浙江 杭州 310012 |
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| 基金项目： | 国家重点研发计划（2017YFA0604104）；国家自然科学基金（41376033，41506026）；中央高校基本科研业务费专项资金（2017B04314）；国家海洋局第二海洋研究所基本科研业务费专项项目（JT1506）。 |
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| 摘 要： | 基于锚碇观测资料，本文分析了南海西北部陆坡区上层海洋对台风“杜苏芮”的动力学和热力学响应特征。在动力学响应方面，台风“杜苏芮”期间上层流速显著增强，混合层纬向流速可达1.20 m/s；“杜苏芮”经过后上层海水运动以近惯性振荡为主(流向顺时针旋转周期在36～40 h之间)。近惯性能量在垂向分布上存在两个高值中心，分别位于混合层和温跃层深度上。近惯性能量耗散过程的e折时间尺度约为3.7 d，我们认为能量的向下传播在局地近惯性能量衰减过程中起主要作用。对能量谱的分析表明，“杜苏芮”作用期间近惯性频率能量相对于其作用前增大了约29.4倍，而全日和半日频率(K1和M2)能量有所减弱。此外，能量谱显示近惯性频率存在明显的“蓝移”现象，即对于纬向和经向流速分量在400 m以浅平均的近惯性振荡频率分别为1.167 f0和1.170 f0(f0为局地惯性频率)。蓝移与近惯性内波的向下传播及正的相对涡度的输入有关。在热力学响应方面，上层海洋在台风的搅拌作用下，40～250 m深度均出现较小增温，最大增温幅度接近1°C；此外70 m以浅盐度的降低可能与台风过境时的降水相关，而Ekman抽吸引起的上升流则可能对70～100 m深度盐度的升高具有重要作用。
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| 关 键 词： | 近惯性振荡 能量谱 动力学响应 热力学响应 南海 |
| 收稿时间： | 2018/7/4 0:00:00 |
| 修稿时间： | 2018/10/9 0:00:00 |
Analysis of upper ocean response to Typhoon Doksuri in the northwest South China Sea |
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| Zhang Qian,Liao Guanghong,Lin Feilong,Jin Weifang and Liang Chujin.Analysis of upper ocean response to Typhoon Doksuri in the northwest South China Sea[J].Acta Oceanologica Sinica (in Chinese),2019,41(7):22-35. |
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| Authors: | Zhang Qian Liao Guanghong Lin Feilong Jin Weifang and Liang Chujin |
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| Institution: | 1.State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Minisitry of Natural Resources, Hangzhou 310012, China2.College of Oceanography, Hohai University, Nanjing 210098, China |
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| Abstract: | Based on the in-situ data from mooring deployed in the northwest South China Sea, we investigate the dynamical and thermal dynamical response of upper ocean to Typhoon Doksuri. In the aspect of dynamic response, as the Typhoon passing, the currents in upper layer enhanced strikingly, the zonal currents in the mixed layer reaches 1.20 m/s. After the passage of Typhoon Doksuri, the currents in the upper layer are dominated by near-inertial oscillation, which rotate clockwise with a period between 36–40 hours. The kinetic energy of near-inertial wave shows two high energetic cores in vertical, which locates at the mixed layer and the thermocline layer, respectively. The estimated e-folding time-scale of near-inertial energy decay is about 3.7 d, and we believe that the downward propagation of energy is the major reason for the decay. The power spectra analysis of currents reveals that power density at inertial frequency, during the period of Typhoon Doksuri, increases about 29.4 times larger than that before the Typhoon arriving. Nevertheless, power density both at diurnal (K1) and semidiurnal (M2) frequency decreases during Typhoon period. Additionally, a blue shift at inertial frequency is identified. We find that the averaged near-internal frequency in upper 400 m is 1.167 f0 for zonal near-inertial currents and 1.170 f0 for meridional near-inertial currents (where f0 is the local inertial frequency). This blue shift is connected with the downward propagation of near-inertial waves and input of positive relative vorticity. In the aspect of thermodynamic response, the temperature rises in the upper layer between 40–250 m depth, due to the stirring induced by strong wind, and the maximum increased temperature amplitude is about 1℃. In addition, the decrease of salinity above 70 m may be related to the precipitation caused by the Typhoon. While the upwelling induced by Ekman pumping may have significant contribution to the increase of salinity at the depth of 70–100 m. |
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| Keywords: | near-inertial oscillations energy spectrum dynamic response thermodynamic response South China Sea |
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