Mooring observations of internal solitary waves in the deep basin west of Luzon Strait
- PDF / 3,366,014 Bytes
- 8 Pages / 595.276 x 841.89 pts (A4) Page_size
- 102 Downloads / 182 Views
Mooring observations of internal solitary waves in the deep basin west of Luzon Strait HUANG Xiaodong1, ZHAO Wei1*, TIAN Jiwei1, YANG Qingxuan1 1
Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China
Received 18 December 2012; accepted 6 May 2013 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2014
Abstract A total of 137 internal solitary waves (ISWs) are captured during a field experiment conducted in the deep basin west of the Luzon Strait (LS) from March to August, 2010. Mooring observations reveal that a fully developed ISW owns a maximum westward velocity of more than 1.8 m/s and an amplitude of about 200 m. The ISWs in the South China Sea (SCS) are most active in July, which may be due to the strong stratification in summer. Most of the ISW episodes are detected around and after the 1st or 15th lunar day, indicating that the ISW in the SCS is triggered by astronomic tides. Half part of the observed ISWs were detected around 19:00 local time, which can be explained by the fact that type-a ISWs emerged in the evening at roughly the same time each day. The propagation direction of the ISWs and the astronomic tides in the LS show that the area south of the Batan Island is probably the main source region of the type-a ISWs, while the area south of Itbayat Island and south of the Batan Island is likely the main source region of the type-b ISWs observed at the mooring. Moreover, for the resonance of semidiurnal internal tides emitting from the double ridges in the LS, the underwater ridge south of the Itbayat Island and south of the Batan Island is believed to favor the generation of the energetic ISWs. Key words: internal solitary wave, South China Sea, observation, nonlinear internal wave Citation: Huang Xiaodong, Zhao Wei, Tian Jiwei, Yang Qingxuan. 2014. Mooring observations of internal solitary waves in the deep basin west of Luzon Strait. Acta Oceanologica Sinica, 33(3): 82–89, doi: 10.1007/s13131-014-0416-7
1 Introduction A significant amount of energy (3.7 TW) from the moon and the sun is incessantly inputted to oceans in the form of astronomical tides, the ultimate fate of which is fueling the dissipation in the bottom friction layers of shallow seas and turbulent mixing in abyssal ocean (Egbert and Ray, 2000). The intense disturbance of a density field will occur when strong astronomical tides flow across abrupt topography features. This signal can propagate a considerable distance from its source region as internal waves (Alford, 2003). The internal solitary wave (ISW) is generally of large concern when issues are related to such tideexcited internal waves, for its large amplitude, short period and ability to retain a constant shape. The ISW in the South China Sea (SCS), with maximum internal amplitude of more than 150 m (Klymak et al., 2006), is among the strongest ISWs in global oceans. According to satellite images, earlier studies also proved the large spatial coverage of the ISWs in the SCS (Liu et al., 1998; Zheng et al., 2007). Based on a o
Data Loading...
