scholarly journals Estimating propagation speed and direction, and vertical displacement of second-mode nonlinear internal waves from ADCP measurements

2022 ◽  
pp. 104644
Author(s):  
Takahiro Endoh ◽  
Eisuke Tsutsumi ◽  
Chang-Su Hong ◽  
Gyu-Nam Baek ◽  
Ming-Huei Chang ◽  
...  
Keyword(s):  
Internal Waves ◽  
Propagation Speed ◽  
Vertical Displacement ◽  
Nonlinear Internal Waves ◽  
Second Mode ◽  
Adcp Measurements

Propagation and transformation of nonlinear internal waves of tidal origin observed in the northeastern East China Sea

2020 ◽  
Author(s):  
Seung-Woo Lee ◽  
SungHyun Nam
Keyword(s):  
East China Sea ◽  
Internal Waves ◽  
Bottom Topography ◽  
Wave Interaction ◽  
Propagation Speed ◽  
East China ◽  
Modal Interactions ◽  
Nonlinear Internal Waves ◽  
China Sea ◽  
Mode 2

<p>Oceanic nonlinear internal waves (NLIWs) play an important role in regional circulation, biogeochemistry, energetics, vertical mixing, and underwater acoustics, causing hazards to marine engineering and submarine navigation. Mainly generated by the interaction of the barotropic tides with the bottom topography, they propagate and transform due to wave-wave interaction process. Here, we present characteristics of first two modes of NLIWs observed using high-resolution spatiotemporal data collected in a relatively flat area in the northeastern East China Sea in May 2015. Six groups of NLIWs were identified from the observations: four groups of mode-1 and two groups of mode-2. The amplitude, propagation speed, and characteristic width of mode-1 NLIWs had ranges of 4–16 m, 0.53–0.56 m s<sup>-1</sup>, and 310–610 m, respectively. The mode-2 NLIWs propagate eastward slowly with a speed less than 0.37 m s<sup>-1</sup> with a comparable amplitude of 4–14 m and longer characteristic width of 540–1920 m. Intermodal interactions may take a role in the evolution of mode-1 NLIWs west of the observational area. Our results characterizing the two modes of NLIWs highlight the significance of propagation and transformation of NLIWs and their modal interactions on a broad and shallow shelf.</p>

Second-mode nonlinear internal waves over a sloping bottom

2013 ◽  
Vol 59 (1) ◽  
pp. 62-67 ◽  
Author(s):  
A. S. Belogortsev ◽  
S. A. Rybak ◽  
A. N. Serebryanyi
Keyword(s):  
Internal Waves ◽  
Nonlinear Internal Waves ◽  
Second Mode ◽  
Sloping Bottom

scholarly journals Statistics of Nonlinear Internal Waves during the Shallow Water 2006 Experiment

2016 ◽  
Vol 33 (4) ◽  
pp. 839-846 ◽  
Author(s):  
Mohsen Badiey ◽  
Lin Wan ◽  
James F. Lynch
Keyword(s):  
Continental Shelf ◽  
Shallow Water ◽  
Internal Waves ◽  
Three Dimensional ◽  
Propagation Speed ◽  
Mapping Technique ◽  
Nonlinear Internal Waves ◽  
Ocean Environment ◽  
Reference Track ◽  
Time Varying Environment

AbstractDuring the Shallow Water Acoustic Experiment 2006 (SW06) conducted on the New Jersey continental shelf in the summer of 2006, detailed measurements of the ocean environment were made along a fixed reference track that was parallel to the continental shelf. The time-varying environment induced by nonlinear internal waves (NLIWs) was recorded by an array of moored thermistor chains and by X-band radars from the attending research vessels. Using a mapping technique, the three-dimensional (3D) temperature field for over a month of NLIW events is reconstructed and analyzed to provide a statistical summary of important NLIW parameters, such as the NLIW propagation speed, direction, and amplitude. The results in this paper can be used as a database for studying the NLIW generation, propagation, and fidelity of nonlinear internal wave models.

scholarly journals Current and Density Observations of Packets of Nonlinear Internal Waves on the Outer New Jersey Shelf

2011 ◽  
Vol 41 (5) ◽  
pp. 994-1008 ◽  
Author(s):  
W. J. Teague ◽  
H. W. Wijesekera ◽  
W. E. Avera ◽  
Z. R. Hallock
Keyword(s):  
New Jersey ◽  
Internal Waves ◽  
Propagation Speed ◽  
Mooring Line ◽  
Outer Continental Shelf ◽  
Density Profiles ◽  
Nonlinear Internal Waves ◽  
Multiple Phase ◽  
The Waves ◽  
Acoustic Doppler Current Profilers

Abstract Closely spaced observations of nonlinear internal waves (NLIWs) were made on the outer continental shelf off New Jersey in June 2009. Nearly full water column measurements of current velocity were made with four acoustic Doppler current profilers (ADCPs) that were moored about 5 km apart on the bottom along a line approximately normal to the bathymetry between water depths of 67 and 92 m. Density profiles were obtained from two vertical strings of temperature and conductivity sensors that were deployed near each of the interior ADCP moorings. In addition, a towed ScanFish provided profiles and fixed-level records of temperature and salinity through several NLIW packets near the moorings. Several case studies were selected to describe the propagation of the NLIWs. One to three solitary waves of depression were observed in five selected packets. There were also occurrences of multiple-phase dispersive wave packets. The average propagation speed corrected for advection of the observed waves was 0.51 ± 0.09 m s−1. The waves were directed primarily shoreward (~northwestward) along the mooring line with average wavelengths and periods of about 300 m and 10 min, respectively. Wave amplitudes and energies decreased with decreasing water depth. The observed wave parameters can be locally described by a two-layer Korteweg–de Vries (KdV) model, except for the decreasing amplitudes, which may be due to shear-induced dissipation and/or bottom drag. The various complementary observations utilized in this study present a unique description of NLIWs.

scholarly journals Shore-Based Video Observations of Nonlinear Internal Waves across the Inner Shelf *,+

2014 ◽  
Vol 31 (3) ◽  
pp. 714-728 ◽  
Author(s):  
Sutara H. Suanda ◽  
John A. Barth ◽  
Rob A. Holman ◽  
John Stanley
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Propagation Speed ◽  
Surface Expression ◽  
Inner Shelf ◽  
Average Width ◽  
Pixel Intensity ◽  
Nonlinear Internal Waves ◽  
Video Observations

Abstract Shore-based video remote sensing is used to observe and continually monitor nonlinear internal waves propagating across the inner shelf. Month-long measurements of velocity from bottom-mounted acoustic Doppler current profilers and temperature from thermistor chains at the 10- and 20-m isobaths are combined with sea surface imagery from a suite of cameras (Argus) to provide a kinematic description of 11 borelike internal waves as they propagate across the central Oregon inner shelf. The surface expression of these waves, commonly seen by eye as alternating rough and smooth bands, are identified by increased pixel intensity in Argus imagery (average width 39 ± 6 m), caused by the convergence of internal wave-driven surface currents. These features are tracked through time and space using 2-min time exposure images and then compared to wave propagation speed and direction from in situ measurements. Internal waves are refracted by bathymetry, and the measured wave speed (~0.15 m s−1) is higher than predicted by linear theory (<0.1 m s−1). Propagating internal waves are also visible in subsampled Argus pixel time series (hourly collections of 17 min worth of 2-Hz pixel intensity from a subset of locations), thus extending the observational record to times without an in situ presence. Results from this 5-month record show that the preferred sea state for successful video observations occurs for wind speeds of 2–5 m s−1. Continued video measurements and analysis of extensive existing Argus data will allow a statistical estimate of internal wave occurrence at a variety of inner-shelf locations.

Observations of nonlinear internal waves of tidal origin in the northeastern East China Sea

2021 ◽  
Author(s):  
Seung-Woo Lee ◽  
SungHyun Nam
Keyword(s):  
East China Sea ◽  
Internal Waves ◽  
Spring Tide ◽  
Propagation Speed ◽  
East China ◽  
Multiple Sources ◽  
Flat Bottom ◽  
Nonlinear Internal Waves ◽  
China Sea ◽  
Regional Circulation

<p>Oceanic nonlinear internal waves (NLIWs) play an important role in regional circulation, biogeochemistry, energetics, vertical mixing, underwater acoustics, marine engineering, and submarine navigation, most commonly generated by the interaction between barotropic tides and bathymetry. Here, we present characteristics of first mode NLIWs observed using high-resolution in-situ data collected using moored and underway temperature sensors in a relatively flat bottom in the northeastern East China Sea during May 15-28, 2015. During the experiment, totally 34 events of first mode NLIWs were identified and characterized with amplitude of 4–16 m, characteristic width of 310–610 m, propagation speed of 0.53–0.56 m s<sup>-1</sup>, and propagation direction (mainly southwestward propagation), respectively. Most NLIWs were observed during period of spring tide with phases locked to semidiurnal barotropic tides. Generation and propagation of the first mode NLIWs observed in the region are discussed in relation to satellite images and historical hydrographic data collected in the region. Our results support significance of first mode NLIWs and their interactions on turbulent mixing and regional circulation particularly in a broad and shallow continental shelves where the NLIWs generated from multiple sources propagate into multi-directions experiencing wave-wave interactions.</p>

scholarly journals Estimation of Propagation Speed and Direction of Nonlinear Internal Waves from Underway and Moored Measurements

2021 ◽  
Vol 9 (10) ◽  
pp. 1089
Author(s):  
Seung-Woo Lee ◽  
Sung-Hyun Nam
Keyword(s):  
Internal Waves ◽  
Ocean Circulation ◽  
Doppler Shift ◽  
Time Lag ◽  
Propagation Speed ◽  
Propagation Direction ◽  
Practical Significance ◽  
Nonlinear Internal Waves ◽  
In Situ Data

Propagation speed and direction of nonlinear internal waves (NLIWs) are important parameters for understanding the generation and propagation of waves, and ultimately clarifying regional ocean circulation. However, these parameters cannot be directly measured from in-situ instruments, but can only be estimated from post-processing in situ data. Herein, we present two methods and an optimal approach to estimate the propagation speed and direction of waves using underway and moored observations. The Doppler shift method estimates these parameters from apparent observations concerning a moving ship using the Doppler shift induced by the changing relative distance of the NLIWs from the moving ship. The time lag method estimates the parameters using the distance between two locations of the NLIW observed at different times and the time lag. To optimize the speed and direction of NLIWs, the difference in the propagation direction independently estimated by the two methods needs to be minimized concerning the optimal propagation speed to yield the optimal propagation direction. The methods were applied to two cases observed in the northern East China Sea in May 2015 and August 2018. This study has practical significance for better estimating the propagation speed and direction of NILWs particularly over a broad continental shelf.

scholarly journals Nonlinear Internal Wave Properties Estimated with Moored ADCP Measurements

2011 ◽  
Vol 28 (6) ◽  
pp. 802-815 ◽  
Author(s):  
Ming-Huei Chang ◽  
Ren-Chieh Lien ◽  
Yiing Jang Yang ◽  
Tswen Yung Tang
Keyword(s):  
Internal Wave ◽  
Principal Direction ◽  
Time Integration ◽  
Propagation Speed ◽  
Vertical Displacement ◽  
Propagation Direction ◽  
Velocity Measurements ◽  
Spreading Effect ◽  
Nonlinear Internal Wave ◽  
Adcp Measurements

Abstract A method is developed to estimate nonlinear internal wave (NLIW) vertical displacement, propagation direction, and propagation speed from single moored acoustic Doppler current profiler (ADCP) velocity observations. The method is applied to three sets of bottom-mounted ADCP measurements taken on the continental slope in the South China Sea in 2006–07. NLIW vertical displacement is computed as the time integration of ADCP vertical velocity observations corrected with the vertical advection of the background flow by the NLIW. NLIW vertical currents displace the background horizontal current and shear by ~150 m. NLIW propagation direction is estimated as the principal direction of the wave-induced horizontal velocity vector, and propagation speed is estimated using the continuity equation in the direction of wave propagation, assuming the wave’s horizontal spatial structure and propagation speed remain constant as the NLIW passes the mooring, typically O(10 min). These NLIW properties are estimated simultaneously and iteratively using the ADCP velocity measurements, corrected for their beam-spreading effect. In most cases, estimates converge to within 3% after four iterations. The proposed method of extracting NLIW properties from velocity measurements is confirmed using NLIWs simulated by the fully nonlinear Dubreil–Jacotin–Long model. Estimates of propagation speed using the ADCP velocity measurements are also in good agreement with those calculated from NLIW arrival times at successive moorings. This study concludes that velocity measurements taken from a single moored ADCP can provide useful estimates of vertical displacement, propagation direction, and propagation speed of large-amplitude NLIWs.

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