Horizontal variability of near-inertial oscillations associated with the passage of a typhoon

• Published in: Journal of Geophysical Research. C. Oceans 2003-12, Vol.108 (C12), p.12.1-n/a
• Main Authors: Hisaki, Yukiharu, Naruke, Tatsunori
• Format: Article
• Language: English
• Subjects: Earth, ocean, space; Exact sciences and technology; HF radar; inertial current; Marine; typhoon
• ISSN: 0148-0227; 2169-9275; 2156-2202; 2169-9291
• DOI: 10.1029/2002JC001683

Surface currents to the east of Okinawa Island were observed by using HF (high‐frequency) ocean radars in August–September 1995. During that period, a typhoon passed near the observation area, and the horizontal variability of near‐inertial oscillations associated with the typhoon passage was estimated. In addition, the near‐inertial amplitudes and horizontal wave number vectors were estimated. These estimations showed that the near‐inertial amplitude was large in the offshore area and small near the coast. The maximum near‐inertial wavelength was estimated to be in the order of 1000 km, and the near‐inertial wave direction was southward and changed to northwestward on 23 August in 1995. A slab model, incorporating low‐frequency currents, was used to calculate near‐inertial currents. It was found that the amplitude of calculated near‐inertial oscillations was also large in the offshore area. Moreover, the phase‐propagation direction of the near‐inertial waves was southward and changed to northwestward or westward on 22 August. The growth rate obtained from the dispersion relation was large in the offshore area, where the near‐inertial amplitude was large.