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Second‐mode internal tides in the East China Sea deduced from historical hydrocasts and a model
Author(s) -
Park JaeHun,
Andres Magdalena,
Martin Paul J.,
Wimbush Mark,
Watts D. Randolph
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl024732
Subject(s) - baroclinity , mode (computer interface) , geology , climatology , china sea , internal tide , trough (economics) , oceanography , continental shelf , internal wave , economics , macroeconomics , computer science , operating system
From historical hydrocasts in the Okinawa Trough region of the East China Sea (ECS), acoustic echo time from 700 dbar to the surface shows a tight relationship with temperature ( T ) except near the 100–200‐dbar layer. This is caused by 2nd‐ or higher‐mode baroclinic variations. Significant out‐of‐phase correlation between upper and lower layer T from the hydrocasts confirms that 2nd‐mode variations are strong. Furthermore, the 2nd‐mode variations are dominant during the ebb tide period, which suggests they are caused by 2nd‐mode internal tides (ITs) generated at the continental shelf break. For comparison, we investigate historical hydrocasts southeast of the Ryukyu Islands, where no significant 2nd‐mode variations are found. A model simulating the M 2 IT agrees qualitatively with these observations: it predicts relatively strong 2nd‐mode IT energy in the ECS, but weak energy in the region southeast of the Ryukyu Islands.