scholarly journals A study on some basic features of inertial oscillations and near-inertial internal waves

Ocean Science ◽  
2017 ◽  
Vol 13 (5) ◽  
pp. 829-836 ◽  
Author(s):  
Shengli Chen ◽  
Daoyi Chen ◽  
Jiuxing Xing
Keyword(s):  
Internal Waves ◽  
Boundary Effect ◽  
Inertial Oscillation ◽  
Inertial Oscillations ◽  
Small Peak ◽  
Non Linear ◽  
Basic Features ◽  
Wind Driven Currents ◽  
Inertial Currents ◽  
Inertial Energy

Abstract. Some basic features of inertial oscillations and near-inertial internal waves are investigated by simulating a two-dimensional (x − z) rectangular basin (300 km  ×  60 m) driven by a wind pulse. For the homogeneous case, near-inertial motions are pure inertial oscillations. The inertial oscillation shows typical opposite currents between the surface and lower layers, which is formed by the feedback between barotropic waves and inertial currents. For the stratified case, near-inertial internal waves are generated at land boundaries and propagate offshore with higher frequencies, which induce tilting of velocity contours in the thermocline. The inertial oscillation is uniform across the whole basin, except near the coastal boundaries ( ∼  20 km), where it quickly declines to zero. This boundary effect is related to great enhancement of non-linear terms, especially the vertical non-linear term (w ∂ u∕ ∂ z). With the inclusion of near-inertial internal waves, the total near-inertial energy has a slight change, with the occurrence of a small peak at  ∼  50 km, which is similar to previous research. We conclude that, for this distribution of near-inertial energy, the boundary effect for inertial oscillations is primary, and the near-inertial internal wave plays a secondary role. Homogeneous cases with various water depths (50, 40, 30, and 20 m) are also simulated. It is found that near-inertial energy monotonously declines with decreasing water depth, because more energy of the initial wind-driven currents is transferred to seiches by barotropic waves. For the case of 20 m, the seiche energy even slightly exceeds the near-inertial energy. We suppose this is an important reason why near-inertial motions are weak and hardly observed in coastal regions.

scholarly journals A study on some basic features of seiches, inertial oscillations and near-inertial internal waves

2017 ◽  
Author(s):  
Shengli Chen ◽  
Daoyi Chen ◽  
Jiuxing Xing
Keyword(s):  
Internal Waves ◽  
Boundary Effect ◽  
Inertial Oscillation ◽  
Phase Lag ◽  
Inertial Oscillations ◽  
Small Peak ◽  
Shallow Basin ◽  
Basic Features ◽  
Inertial Currents ◽  
Inertial Energy

Abstract. Some basic features of seiches, inertial oscillations and near-inertial internal waves are investigated by simulating a two-dimensional (x-z) shallow basin initialized by a wind pulse. Two cases with and without the vertical stratification are conducted. For the homogeneous case, seiches and inertial oscillations dominate. We find even modes of seiches disappear, which is attributed to a superposition of two seiches generated at east and west coastal boundaries. They have anti-symmetric elevations and a phase lag of nπ, thus their even modes cancel each other. The inertial oscillation shows typical opposite currents between surface and lower layers, which is formed by the feedback between barotropic waves and inertial currents. For the stratified case, near-inertial internal waves are generated are generated at land boundaries and propagate offshore with increasing frequencies, which induce tilting of velocity contours in the thermocline. The inertial oscillation is uniform across the whole basin, except near the coastal boundaries (~ 20 km) where it quickly declines to zero. This boundary effect is related to great enhancement of nonlinear terms, especially the vertical nonlinear term (w&#8706u / &#8706z). With inclusion of near-inertial internal waves, the total near-inertial energy has a slight change, with occurrence of a small peak at ~ 50 km, which is similar to previous researches. We conclude that, for this distribution of near-inertial energy, the boundary effect for inertial oscillations is primary, and the near-inertial internal wave plays a secondary role.

Radiation damping of inertial oscillations in the upper ocean

1978 ◽  
Vol 88 (2) ◽  
pp. 289-308 ◽  
Author(s):  
T. H. Bell
Keyword(s):  
Internal Wave ◽  
Wave Field ◽  
Energy Flux ◽  
Mixed Layer ◽  
Upper Ocean ◽  
Inertial Oscillation ◽  
Inertial Oscillations ◽  
Near Surface ◽  
Oscillation Energy ◽  
Inertial Currents

Turbulent motions within the wind-mixed layer, which is advected by near-surface inertial oscillations, excite internal gravity waves in the underlying ocean layers. Momentum transport in the radiated wave field results in a drag force on the inertial currents. Because the magnitude of the inertial currents is large compared with the turbulence intensity, the resultant rate of dissipation of inertial oscillation energy is approximately equal to the energy flux in the radiated wave field. Using linear internal wave theory, asymptotic results are derived for the energy flux in terms of the Brunt-Väisälä frequency N below the mixed layer, the magnitude U0 of the inertial current, the integral length scale l of the mixed-layer turbulence and the mean-square displacement 〈ζ20〉 of the base of the mixed layer. For representative conditions, we estimate an energy flux of 1-10 erg/cm2 s into relatively short (wavelength of order 2πU0/N) high frequency (of order, but less than, N) internal waves. The resultant decay times for inertial oscillation energy range from a day to a week or so, in agreement with reported observations on the decay of inertial oscillations in the upper ocean. The estimated energy flux is comparable in magnitude to estimates for other internal wave generation mechanisms, indicating that, in addition to being a significant sink of inertial energy, this process may locally represent a significant source of internal wave energy in the open ocean.

Field Studies of Non-Linear Internal Waves in Lakes on the Globe

2011 ◽  
pp. 23-103 ◽  
Author(s):  
N. Filatov ◽  
A. Terzevik ◽  
R. Zdorovennov ◽  
V. Vlasenko ◽  
N. Stashchuk ◽  
...  
Keyword(s):  
Internal Waves ◽  
Field Studies ◽  
Non Linear

Communication and Nursing Relationships

2011 ◽  
pp. 25-39
Author(s):  
Kyung Rim Shin ◽  
Dukyoo Jung ◽  
Su Jin Shin
Keyword(s):  
Enriched Environment ◽  
Non Linear ◽  
Basic Features

Communication and relationships are central to nursing. The non-linear quality of communication is discussed and the challenge for nursing to carry quality communication into a technology enriched environment considered. Basic features of communication are laid out.

Simulation of Strong Inertial Currents to Support Preliminary Engineering Offshore Namibia

2013 ◽  
Author(s):  
Gus Jeans ◽  
Ian Wade
Keyword(s):  
Ocean Current ◽  
Current Profile ◽  
Sea Breezes ◽  
The Public ◽  
Current Regime ◽  
Local Current ◽  
Exploration Drilling ◽  
Inertial Currents ◽  
Inertial Energy

The vertical profile of ocean current needs to be characterised for preliminary engineering applications such as exploration drilling. The acquisition of suitable current profile data can be a key challenge, especially in relatively unexplored deepwater frontier regions. Recent years have seen a dramatic increase in the use of ocean current models for this purpose, frequently involving freely available data from the HYCOM consortium. These data have proven reliable in some locations, but the accuracy remains questionable, or unproven, in many others. This paper describes a study in which it was clear from the outset that HYCOM would not represent dominant features of the local current regime. This concerned the region offshore Namibia, near 30°S, at which latitude the inertial period of natural ocean oscillation equals the diurnal period of 24 hours. This region is also subjected to relatively strong diurnal sea breezes, which can drive nearly resonant inertial responses in the ocean, which can, in turn, dominate the current regime. The spatial resolution of the wind field used to drive the global HYCOM model is insufficient to resolve this critical wind forcing, so the resulting model currents cannot represent the dominant features. Fortunately some relevant measurements were well documented in the public domain, from which a pragmatic inertial current simulation methodology was developed. Lack of inertial energy was actually beneficial for using HYCOM daily spot values to represent other, longer term, components of the flow. If inertial currents had been represented in the model, then more frequent values would be required to capture them. HYCOM data proved useful for representing long term inter-annual variability in the features it does represent, including meanders in the seasonal Benguala current.

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