Open AccessSource and propagation of internal solitary waves in the northeastern South China Sea
Author(s) -
Zhao Zhongxiang,
Alford Matthew H.
Publication year - 2006
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006jc003644
Subject(s) - barotropic fluid , internal tide , geology , bathymetry , internal wave , oceanography , amplitude , ridge , tidal waves , stratification (seeds) , tidal current , seismology , physics , paleontology , seed dormancy , germination , botany , quantum mechanics , dormancy , biology
Large‐amplitude internal solitary waves (ISWs) observed near Dongsha Island in the South China Sea originate in tide‐topography interactions at Luzon Strait. Their arrival times at two moorings (S7 at 117°17′E, 21°37′N, and Y at 117°13.2′E, 21°2.8′N) are investigated, with respect to model‐predicted barotropic tidal currents over Lan‐Yu ridge at Luzon Strait. Each ISW packet can be associated with a westward tidal current peak. The time lags between the ISWs and the barotropic tidal currents are 57.6 ± 0.9 hours at S7 and 55.1 ± 1.0 hours at Y, consistent with the mode‐one internal waves propagating nondispersively through the region's bathymetry and climatological stratification. Larger ISWs usually arrive earlier than smaller ones, consistent with the theoretical relation between nonlinear wave speed and wave amplitude. The observation that the ISWs are associated with westward tidal currents, with/without the presence of earlier eastward tidal currents, suggests that they are generated by nonlinear steepening of internal tides, rather than by the lee‐wave mechanism. An idealized nonlinearization distance, over which the ISWs are generated in internal tide troughs, is estimated to be 260 ± 40 km from Luzon Strait.