scholarly journals Dynamics of the Diurnal Warm Layer: Surface Jet, High-Frequency Internal Waves, and Mixing

2020 ◽  
Vol 50 (7) ◽  
pp. 2053-2070
Author(s):  
Hemantha W. Wijesekera ◽  
David W. Wang ◽  
Ewa Jarosz
Keyword(s):  
Internal Waves ◽  
High Frequency ◽  
Heat Content ◽  
Sea Breeze ◽  
Wave Interactions ◽  
Solar Insolation ◽  
Vertical Displacements ◽  
Surface Jet ◽  
The Right ◽  
Stability Frequency

AbstractEvolution of a thermally stratified diurnal warm layer (DWL), including the formation and decay of a daytime surface-layer jet, high-frequency internal waves, and mixing were examined from observations collected during July 2016, near 93.75°W, 28°N, on the outer Louisiana–Texas continental shelf in the Gulf of Mexico, when the ocean surface was experiencing a weak sea breeze (<5 m s−1) and strong solar insolation. While winds and surface waves were weak, the DWL was formed with stratification strengthening and stability frequency reaching 14 cycles per hour at 2-m depth, while inhibiting turbulence below the DWL. A surface-intensified jet developed during afternoon hours. The jet, oriented to the right of the wind stress with a speed of about 10 cm s−1 at 2 m, veered and decreased with depth. The magnitude of the diurnal jet was correlated with the heat content anomaly in the DWL. Internal waves with periods ranging from 5 min to 4 h were observed in the upper 4 m. Temperature fluctuations were ~ ±0.2°C, and the corresponding vertical displacements varied from 0.5 to 1 m. These fluctuations appeared during afternoon hours when the Richardson number dropped below the critical value of 0.25 followed by energetic mixing. The daytime jet and the high-frequency fluctuations disappeared a few hours after sunset. Internal waves were likely excited by Kelvin–Helmholtz instabilities and by surface wave and internal wave interactions. Mixing resulting from the dissipation of daytime internal waves is an important factor in regulating sea surface temperature in the DWL.

P367: High frequency deep rTMS over the right homologous Broca’s region improves naming in chronic post-stroke aphasia: a pilot study

2014 ◽  
Vol 125 ◽  
pp. S145
Author(s):  
R. Chieffo ◽  
F. Ferrari ◽  
P. Battista ◽  
E. Houdayer ◽  
A. Nuara ◽  
...  
Keyword(s):  
Pilot Study ◽  
High Frequency ◽  
Post Stroke ◽  
Broca’S Region ◽  
The Right

Tidal Internal Waves in the Bransfield Strait, Antarctica

2021 ◽  
Author(s):  
Eugene Morozov ◽  
Dmitry Frey ◽  
Elizaveta Khimchenko
Keyword(s):  
Internal Waves ◽  
Bottom Topography ◽  
Pressure Sensors ◽  
Internal Tide ◽  
Internal Tides ◽  
South Shetland Islands ◽  
Flat Bottom ◽  
Bransfield Strait ◽  
Vertical Displacements ◽  
Rfbr Grant

&lt;p&gt;Observations of tidal internal waves in the Bransfield Strait, Antarctica, are analyzed. The measurements were carried out for 14 days on a moored station equipped with five autonomous temperature and pressure sensors. The mooring was deployed on the slope of Nelson Island (South Shetland Islands archipelago) over a depth of 70 m at point 62&amp;#176;21&amp;#42892; S, 58&amp;#176;49&amp;#42892; W. Analysis is based on the fluctuations of isotherms. &amp;#160;Vertical displacements of temperature revealed that strong internal vertical oscillations up to 30&amp;#8211;40 m are caused by the diurnal internal tide. Spectral analysis of vertical displacements of the 0.9&amp;#176;C isotherm showed a clear peak at a period of 24 h. It is known that the tides in the Bransfield Strait are mostly mixed diurnal and semidiurnal, but during the Antarctic summer, diurnal tide component may intensify. The velocity ellipses of the barotropic tidal currents were estimated using the global tidal model TPXO9.0. It was found that tidal ellipses rotate clockwise with a period of 24 h and anticlockwise with a period of 12 h. The waves are forced due to the interaction of the barotropic tide with the bottom topography. Diurnal internal tides do not develop at latitudes higher than 30&amp;#186; over flat bottom. The research was supported by RFBR grant 20-08-00246.&lt;/p&gt;

scholarly journals Energy transformations and dissipation of nonlinear internal waves over New Jersey's continental shelf

2010 ◽  
Vol 17 (4) ◽  
pp. 345-360 ◽  
Author(s):  
E. L. Shroyer ◽  
J. N. Moum ◽  
J. D. Nash
Keyword(s):  
Continental Shelf ◽  
Internal Waves ◽  
Turbulent Mixing ◽  
Internal Tide ◽  
Flux Divergence ◽  
Wave Interactions ◽  
Nonlinear Internal Waves ◽  
Dissipative Loss ◽  
Peak Energy

Abstract. The energetics of large amplitude, high-frequency nonlinear internal waves (NLIWs) observed over the New Jersey continental shelf are summarized from ship and mooring data acquired in August 2006. NLIW energy was typically on the order of 105 Jm−1, and the wave dissipative loss was near 50 W m−1. However, wave energies (dissipations) were ~10 (~2) times greater than these values during a particular week-long period. In general, the leading waves in a packet grew in energy across the outer shelf, reached peak values near 40 km inshore of the shelf break, and then lost energy to turbulent mixing. Wave growth was attributed to the bore-like nature of the internal tide, as wave groups that exhibited larger long-term (lasting for a few hours) displacements of the pycnocline offshore typically had greater energy inshore. For ship-observed NLIWs, the average dissipative loss over the region of decay scaled with the peak energy in waves; extending this scaling to mooring data produces estimates of NLIW dissipative loss consistent with those made using the flux divergence of wave energy. The decay time scale of the NLIWs was approximately 12 h corresponding to a length scale of 35 km (O(100) wavelengths). Imposed on these larger scale energetic trends, were short, rapid exchanges associated with wave interactions and shoaling on a localized topographic rise. Both of these events resulted in the onset of shear instabilities and large energy loss to turbulent mixing.

scholarly journals High-frequency internal waves near the Luzon Strait observed by underwater gliders

2013 ◽  
Vol 118 (2) ◽  
pp. 774-784 ◽  
Author(s):  
Daniel L. Rudnick ◽  
T. M. Shaun Johnston ◽  
Jeffrey T. Sherman
Keyword(s):  
Internal Waves ◽  
High Frequency ◽  
Luzon Strait ◽  
Underwater Gliders

Diaphragmatic flutter

2018 ◽  
Vol 18 (3) ◽  
pp. 224-226 ◽  
Author(s):  
Dean Walton ◽  
Michael Bonello ◽  
Malcolm Steiger
Keyword(s):  
Respiratory Distress ◽  
Medical Treatment ◽  
Abdominal Wall ◽  
Phrenic Nerve ◽  
High Frequency ◽  
Rare Disorder ◽  
Nerve Crush ◽  
Irregular Variable ◽  
The Right ◽  
High Index Of Suspicion

A 78-year-old woman presented with involuntary movements of her abdomen, which started after a right hemispheric stroke. She had irregular, variable, hyperkinetic predominantly right-sided abdominal wall movements. MR scan of brain confirmed a recent infarct in the right occipitotemporal lobe and the right cerebellum. Diaphragmatic fluoroscopy confirmed high-frequency flutter as the cause of her abdominal movements and confirmed the diagnosis of van Leeuwenhoek’s disease. Anthonie van Leeuwenhoek first described this condition in 1723 and had the condition himself. He was a Dutch businessman who is often acknowledged as the first microscopist and microbiologist. He disagreed with his physician who attributed his ailment as being of cardiac origin. Diaphragmatic flutter is a rare disorder that requires a high index of suspicion with symptoms including abnormal abdominal wall movements, dyspnoea and respiratory distress. Despite medical treatment, the patient was still highly symptomatic, so she is currently being considered for a phrenic nerve crush.

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