A scaling law of internal run-up duration

作者：Grue John^*; Sveen J Kristian

来源：Ocean Dynamics, 2010, 60(4): 993-1006.

DOI：10.1007/s10236-010-0284-4

• Internal run-up
• Bottom current
• Onshore flow duration
• Stratified flow
• Undular internal bores
• Internal solitons
• Boluses

Wave tank experiments with long internal waves of elevation, of different initial length l, moving in a two-fluid system, interacting with a weak slope of 0.045 rad, show an onshore flow of the dense water, at the undisturbed pycnocline-slope intersection, of duration 11.3 root l/g' (g' reduced gravity). This period corresponds to that of a strong bottom current event measured in the stratified ocean at the Ormen Lange gas field, at 850 m depth, lasting for 24 hrs, corresponding to 11.2 root l/g', using the width l = 300 km of the Norwegian Atlantic Current (NAC) at the site as length scale, suggesting a lateral sloshing motion of the NAC causing the event. The onshore velocity of the dense fluid has a maximal velocity of 0.4 root g'h(2) in laboratory and 0.5 ms(-1) = 0.3 root g'h(2) in the field(h(2) mixed upper layer thickness). Run-up of the dense fluid, beyond the undisturbed pycnocline-slope intersection, has initially a front velocity of 0.35 root g'h(2), corresponding to the velocity of the head of a density current on a flat bottom. Due to disintegration, an initially depressed pycnocline results in comparatively smaller run-up and velocity. While moving past the turning point, a dispersive wave train is formed in the back part of the depression wave, developing by breaking into a sequence of up to eight boluses moving by the undisturbed pycnocline-slope intersection.

• 出版日期2010-8