南海东北部陆架区台风“卡努”的近惯性振荡响应

Near-inertial oscillation response of typhoon"Kanu"in the northeastern continental shelf of the South China Sea

基于2017年10月南海东北部陆架区的潜标观测资料,分析了南海东北部陆架区海洋对台风“卡努”的近惯性响应特征,研究了近惯性内波生成、传播和消亡等演变规律。研究结果表明:在动力学响应方面,台风过境期间全水深流速显著增强,表层最大流速达到145 cm/s;近惯性流速在垂向上存在的两个高值区分别位于表层和中层,中层近惯性振荡影响时间最长超过12 d;近惯性振荡e折时间尺度大约为7.6 d。近惯性内波的垂向群速度为0.042 cm/s;近惯性内波会引起波-波相互作用、近惯性波与全日内波的耦合波;在台风“卡努”作用期间存在显著的频率“蓝移”现象。在热力学响应方面,台风会引起表层水温下降,底层水温上升。

Based on the submersible observations in the northeastern continental shelf of the South China Sea in October 2017,the characteristics of the near-inertial response of the oceans in the northeastern continental shelf to typhoon"Kanu"are analyzed,and the evolution pattern of the near-inertial internal wave generation,propagation and extinction is studied.The results show that,in terms of dynamic response,the current velocity throughout the water column increases significantly during the typhoon transit,and the maximum surface velocity reaches 145 cm/s.The two high value areas of the near-inertial velocity vertically are located in the surface layer and the middle layer,and the influence time of near-inertial oscillation in the middle layer is longer than 12 d.The e-folding time scale of the near-inertial oscillations is about 7.6 d.The vertical group velocity of the near-inertial internal wave is 0.042 cm/s.The near-inertial internal wave could cause wave-wave interaction and coupled wave between of the near-inertial wave and the all-day internal wave.During typhoon period,there is a significant frequency"blue-shift"phenomenon during typhoon"Kanu".In terms of thermodynamic response,the typhoon causes the surface water temperature decrease and bottom water temperature increase.