Observations of Inertial Wave Events near the Continental Slope off Goban Spur

2005 ◽  
Vol 35 (8) ◽  
pp. 1329-1340 ◽  
Author(s):  
Hendrik M. van Aken ◽  
Leo R. M. Maas ◽  
Hans van Haren
Keyword(s):  
Continental Slope ◽  
Bottom Layer ◽  
Peak Frequency ◽  
High Energy ◽  
Boundary Current ◽  
Temperature Spectrum ◽  
Inertial Wave ◽  
Speculative Hypothesis ◽  
The Waves ◽  
Goban Spur

Abstract Near-inertial waves were observed during the Ocean Margin Exchange (OMEX-I) experiments with current meters over the continental slope near Goban Spur. The strongest inertial motion was observed in the bottom layer, about 50 m above the 1000-m isobath. There the waves were slightly (1.7%) superinertial and the bottom slope appeared to be critical for the near-inertial peak frequency, allowing the velocity vector to follow the sloping bottom. The vertical velocity component of this motion was responsible for the near-inertial spectral peak in the temperature spectrum, which was also observed in the bottom layer. Evidence was found supporting the speculative hypothesis that high-energy near-inertial wave events were produced during geostrophic adjustment in the variable deep eastern-boundary current over the slope near Goban Spur.

scholarly journals Individual Alpha Peak Frequency, an Important Biomarker for Live Z-Score Training Neurofeedback in Adolescents with Learning Disabilities

2021 ◽  
Vol 11 (2) ◽  
pp. 167
Author(s):  
Rubén Pérez-Elvira ◽  
Javier Oltra-Cucarella ◽  
José Antonio Carrobles ◽  
Minodora Teodoru ◽  
Ciprian Bacila ◽  
...  
Keyword(s):  
Learning Disabilities ◽  
Pediatric Population ◽  
Peak Frequency ◽  
Normative Values ◽  
Z Score ◽  
Absolute Power ◽  
The Individual ◽  
And Behavior ◽  
The Waves ◽  
Alpha Peak

Learning disabilities (LDs) have an estimated prevalence between 5% and 9% in the pediatric population and are associated with difficulties in reading, arithmetic, and writing. Previous electroencephalography (EEG) research has reported a lag in alpha-band development in specific LD phenotypes, which seems to offer a possible explanation for differences in EEG maturation. In this study, 40 adolescents aged 10–15 years with LDs underwent 10 sessions of Live Z-Score Training Neurofeedback (LZT-NF) Training to improve their cognition and behavior. Based on the individual alpha peak frequency (i-APF) values from the spectrogram, a group with normal i-APF (ni-APF) and a group with low i-APF (li-APF) were compared in a pre-and-post-LZT-NF intervention. There were no statistical differences in age, gender, or the distribution of LDs between the groups. The li-APF group showed a higher theta absolute power in P4 (p = 0.016) at baseline and higher Hi-Beta absolute power in F3 (p = 0.007) post-treatment compared with the ni-APF group. In both groups, extreme waves (absolute Z-score of ≥1.5) were more likely to move toward the normative values, with better results in the ni-APF group. Conversely, the waves within the normal range at baseline were more likely to move out of the range after treatment in the li-APF group. Our results provide evidence of a viable biomarker for identifying optimal responders for the LZT-NF technique based on the i-APF metric reflecting the patient’s neurophysiological individuality.

scholarly journals Reversal of freshening trend of Antarctic Bottom Water in the Australian-Antarctic Basin during 2010s

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
S. Aoki ◽  
K. Yamazaki ◽  
D. Hirano ◽  
K. Katsumata ◽  
K. Shimada ◽  
...  
Keyword(s):  
Continental Slope ◽  
Bottom Water ◽  
Ross Sea ◽  
Bottom Layer ◽  
Ice Shelves ◽  
West Antarctic ◽  
Sea Bottom ◽  
Salinity Increase ◽  
Bottom Waters ◽  
Late Twentieth

Abstract The Antarctic continental margin supplies the densest bottom water to the global abyss. From the late twentieth century, an acceleration in the long-term freshening of Antarctic Bottom Waters (AABW) has been detected in the Australian-Antarctic Basin. Our latest hydrographic observations reveal that, in the late 2010s, the freshening trend has reversed broadly over the continental slope. Near-bottom salinities in 2018–2019 were higher than during 2011–2015. Along 170° E, the salinity increase between 2011 and 2018 was greater than that observed in the west. The layer thickness of the densest AABW increased during the 2010s, suggesting that the Ross Sea Bottom Water intensification was a major source of the salinity increase. Freshwater content on the continental slope decreased at a rate of 58 ± 37 Gt/a in the near-bottom layer. The decadal change is very likely due to changes in Ross Sea shelf water attributable to a decrease in meltwater from West Antarctic ice shelves for the corresponding period.

scholarly journals A NuSTAR view of powerful γ-ray loud blazars

2019 ◽  
Vol 627 ◽  
pp. A72 ◽  
Author(s):  
G. Ghisellini ◽  
M. Perri ◽  
L. Costamante ◽  
G. Tagliaferri ◽  
T. Sbarrato ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Peak Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
Γ Ray ◽  
The Universe ◽  
Jet Power

We observed three blazars at z >  2 with the NuSTAR satellite. These were detected in the γ-rays by Fermi/LAT and in the soft X-rays, but have not yet been observed above 10 keV. The flux and slope of their X-ray continuum, together with Fermi/LAT data allows us to estimate their total electromagnetic output and peak frequency. For some of them we were able to study the source in different states, and investigate the main cause of the different observed spectral energy distribution. We then collected all blazars at redshifts greater than 2 observed by NuSTAR, and confirm that these hard and luminous X-ray blazars are among the most powerful persistent sources in the Universe. We confirm the relation between the jet power and the disk luminosity, extending it at the high-energy end.

Sinking particle fluxes from the euphotic zone over the continental slope of an eastern boundary current region

1996 ◽  
Vol 54 (6) ◽  
pp. 1097-1122 ◽  
Author(s):  
M. A. Pena ◽  
K. L. Denman ◽  
J. R. Forbes ◽  
S. E. Calvert ◽  
R. E. Thomson
Keyword(s):  
Continental Slope ◽  
Euphotic Zone ◽  
Boundary Current ◽  
Eastern Boundary ◽  
Eastern Boundary Current ◽  
Current Region ◽  
Particle Fluxes

scholarly journals Coherence of Western Boundary Pressure at the RAPID WAVE Array: Boundary Wave Adjustments or Deep Western Boundary Current Advection?

2013 ◽  
Vol 43 (4) ◽  
pp. 744-765 ◽  
Author(s):  
Shane Elipot ◽  
Chris Hughes ◽  
Sofia Olhede ◽  
John Toole
Keyword(s):  
Continental Slope ◽  
Time Scales ◽  
Propagation Speed ◽  
Large Error ◽  
Western Boundary ◽  
Ocean Bottom ◽  
Boundary Current ◽  
Coherent Signals ◽  
Woods Hole Oceanographic Institution ◽  
Meridional Transport

Abstract This study investigates the coherence between ocean bottom pressure signals at the Rapid Climate Change programme (RAPID) West Atlantic Variability Experiment (WAVE) array on the western North Atlantic continental slope, including the Woods Hole Oceanographic Institution Line W. Highly coherent pressure signals propagate southwestward along the slope, at speeds in excess of 128 m s−1, consistent with expectations of barotropic Kelvin-like waves. Coherent signals are also evidenced in the smaller pressure differences relative to 1000-m depth, which are expected to be associated with depth-dependent basinwide meridional transport variations or an overturning circulation. These signals are coherent and almost in phase for all time scales from 3.6 years down to 3 months. Coherence is still seen at shorter time scales for which group delay estimates are consistent with a propagation speed of about 1 m s−1 over 990 km of continental slope but with large error bounds on the speed. This is roughly consistent with expectations for propagation of coastally trapped waves, though somewhat slower than expected. A comparison with both Eulerian currents and Lagrangian float measurements shows that the coherence is inconsistent with a propagation of signals by advection, except possibly on time scales longer than 6 months.

Structure and Microwave Absorption Properties of Ho-Fe-Si Alloys

2018 ◽  
Vol 914 ◽  
pp. 117-123 ◽  
Author(s):  
Jia Liang Luo ◽  
Shun Kang Pan ◽  
Li Chun Cheng ◽  
Pei Hao Lin ◽  
Yu He ◽  
...  
Keyword(s):  
Ball Milling ◽  
Matching Condition ◽  
Peak Frequency ◽  
High Energy ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Arc Melting ◽  
Microwave Absorbing Materials ◽  
Milling Method ◽  
Si Content

The Ho2Fe17-xSix (x=0.0, 0.1, 0.2, 0.3) alloys were prepared by arc melting and high energy ball milling method. The influence of the Si substitution on phase structure, morphology and electromagnetic parameters were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vector network analyzer (VNA), respectively. The results show that the Ho-Fe-Si particles are flaky after the ball milling. The minimum absorption peak frequency shifts towards a lower frequency region with the increasing of Si content. The minimum RL of Ho2Fe16.7Si0.3 reaches-42.96 dB at 9.76 GHz, and the frequency bandwidth of R<-10 dB reaches about 2.64 GHz with the best matching condition d=1.6 mm. The reflection loss with the thickness ranging of 1.2-3.0 mm could reach-10 dB, which indicates the particles be considered as the promising microwave absorbing materials with a good absorption properties.

Some motivations for a very costly long-range programme on high-energy neutrino physics at C.E.R.N

1964 ◽  
Vol 278 (1374) ◽  
pp. 369-390 ◽  
Keyword(s):  
Neutrino Physics ◽  
Interaction Energy ◽  
Weak Interactions ◽  
High Energy ◽  
Potential Interaction ◽  
Scattering Process ◽  
Β Decay ◽  
Classic Theory ◽  
The Waves ◽  
Present Understanding

1. The basis of our present understanding of weak interactions is a new version of the classic theory of Fermi of 1934. Fermi considered the nucleon reactions, e - + p ⇄ n + v . According to the arrow direction, this represents either electron K -capture or neutron β-decay. He treated the interaction as a point-like scattering process, that is as a process in which the range of the potential V(r a — r b ) vanished. This is equiva­lent to converting the potential interaction energy, H int. = ∫ ψ ' b ψ ' a V (r a – r b ) ψ a ψ b dr a dr b , where ψ a , ψ b are the waves representing the incoming particles and ψ ' a , ψ ' b , the outgoing ones, into the limit H int. = G ∫ ψ ' a ψ ' b ψ a ψ b dr = G ∫ ( ψ ' a ψ a ) ( ψ ' b ψ b ) dr, where r is the volume variable.

scholarly journals Speed and Evolution of Nonlinear Internal Waves Transiting the South China Sea

2010 ◽  
Vol 40 (6) ◽  
pp. 1338-1355 ◽  
Author(s):  
Matthew H. Alford ◽  
Ren-Chieh Lien ◽  
Harper Simmons ◽  
Jody Klymak ◽  
Steve Ramp ◽  
...  
Keyword(s):  
South China Sea ◽  
Continental Slope ◽  
Internal Waves ◽  
South China ◽  
The South China Sea ◽  
Internal Tides ◽  
Deep Basin ◽  
Nonlinear Internal Waves ◽  
The Waves ◽  
Upper Slope

Abstract In the South China Sea (SCS), 14 nonlinear internal waves are detected as they transit a synchronous array of 10 moorings spanning the waves’ generation site at Luzon Strait, through the deep basin, and onto the upper continental slope 560 km to the west. Their arrival time, speed, width, energy, amplitude, and number of trailing waves are monitored. Waves occur twice daily in a particular pattern where larger, narrower “A” waves alternate with wider, smaller “B” waves. Waves begin as broad internal tides close to Luzon Strait’s two ridges, steepening to O(3–10 km) wide in the deep basin and O(200–300 m) on the upper slope. Nearly all waves eventually develop wave trains, with larger–steeper waves developing them earlier and in greater numbers. The B waves in the deep basin begin at a mean speed of ≈5% greater than the linear mode-1 phase speed for semidiurnal internal waves (computed using climatological and in situ stratification). The A waves travel ≈5%–10% faster than B waves until they reach the continental slope, presumably because of their greater amplitude. On the upper continental slope, all waves speed up relative to linear values, but B waves now travel 8%–12% faster than A waves, in spite of being smaller. Solutions of the Taylor–Goldstein equation with observed currents demonstrate that the B waves’ faster speed is a result of modulation of the background currents by an energetic diurnal internal tide on the upper slope. Attempts to ascertain the phase of the barotropic tide at which the waves were generated yielded inconsistent results, possibly partly because of contamination at the easternmost mooring by eastward signals generated at Luzon Strait’s western ridge. These results present a coherent picture of the transbasin evolution of the waves but underscore the need to better understand their generation, the nature of their nonlinearity, and propagation through a time-variable background flow, which includes the internal tides.

scholarly journals WAVES IN WETLANDS: HURRICANE GUSTAV

2011 ◽  
Vol 1 (32) ◽  
pp. 29 ◽  
Author(s):  
Jane McKee Smith ◽  
Robert E. Jensen ◽  
Andrew B. Kennedy ◽  
J. Casey Dietrich ◽  
Joannes J. Westerink
Keyword(s):  
Circulation Model ◽  
Wave Model ◽  
High Energy ◽  
Generation Model ◽  
Wave Modeling ◽  
Wave Measurements ◽  
The Waves ◽  
Variable Water ◽  
Water Depths ◽  
Made In

Few wave measurements have been made in wetlands during high-energy, surge events, such as hurricanes. During Hurricane Gustav in 2008, many nearshore wave measurements were made in Southeastern Louisiana. These data are used to verify a nearshore wave modeling system and to explore the characteristics of hurricane waves in wetlands. The modeling system consists of the wave generation model WAM, the nearhsore wave model STWAVE, and the circulation model ADCIRC. The measurements confirm reasonable success in modeling the waves. The measurements and modeling also expose some of the problems of measuring waves in highly-variable water depths under hurricane forcing and modeling waves in rapidly degrading wetlands.

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