Based on mooring observations from Aug.1,2016 to Dec.14,2017,the characteristics and underlying mechanisms of near-inertial waves(NIWs)observed east of the Philippines were studied.Three strong NIW events were investigated in detail.The NIWs in Event I were induced by typhoon Lan and had the strongest magnitudes of 0.35 m/s.The maximum near-inertial kinetic energy(NIKE)was shown at the ocean surface.The NIW in Event Ⅱ was stimulated by a moderate cyclonic wind with the extreme NIKE located at about 110-m depth.The existence of a cyclonic eddy during Events Ⅰ and Ⅱ led to a blue shift of near-inertial frequencies.For Event Ⅲ,the surface near-inertial signals were also induced by local weak wind,whereas the real generation mechanisms for the subsurface NIWs remain unclear.In particular,during Event Ⅲ,there was a nonlinear wave-wave interaction between NIWs and semidiurnal(D2)tides,which further induced strong D2±f waves.Overall,the NIWs in the three events exhibited distinct vertical structures.The NIWs in Events Ⅰ and Ⅱ were dominated by lower modes with elevated NIKE well confined to the upper 250 m and 270 m,respectively.In contrast,the NIW Event Ⅲ was dominated by higher modes and the NIWs penetrated downward beyond 360 m.Such deep penetration of NIWs could be attributed to the weak wind stress curl and positive sea level anomalies associated with an anticyclonic eddy.In addition,the three NIW events had e-folding timescales of less than 7 days.

Shengming YUAN;Xiaomei YAN;Linlin ZHANG;Bing YANG;Chongguang PANG;Dunxin HU

Key Laboratory of Ocean Circulation and Waves,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;College of Earth Science,University of Chinese Academy of Sciences,Beijing 100049,China;Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China;Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China

海洋湖沼学报（英文版）

[1]Shengming YUAN;Xiaomei YAN;Linlin ZHANG;Bing YANG;Chongguang PANG;Dunxin HU-.The near-inertial waves observed east of the Philippines)[J].海洋湖沼学报（英文版）,2022(05):1889-1908

NIWs,NIW,NIKE,semidiurnal

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