scholarly journals Propagation Directions of Ocean Surface Waves inside Tropical Cyclones

2018 ◽  
Vol 48 (7) ◽  
pp. 1495-1511 ◽  
Author(s):  
Paul A. Hwang ◽  
Edward J. Walsh
Keyword(s):  
Wave Propagation ◽  
Tropical Cyclones ◽  
Wind Field ◽  
Rapid Change ◽  
Primary System ◽  
Coverage Area ◽  
Multiple Wave ◽  
Translation Speed ◽  
Single Wave ◽  
The Right

AbstractSurface wave propagation inside tropical cyclones (TCs) is complicated and multiple wave systems are frequently observed. The directional wave spectra acquired by hurricane hunters are analyzed to quantify its azimuthal and radial variations. Referenced to the hurricane heading, the dominate feature in the front half of the TC coverage area is single wave systems propagating toward left and left-front. Multiple wave systems are generally observed in the back and right quarters outside the radius of maximum wind (RMW). The directional differences and locations of occurrences of multisystem spectra are Gaussian distributed. The directional differences of the secondary and tertiary wave systems from the primary system are centered around 60°–70°. The minor systems are more likely on the left-hand side of the primary system than on the right-hand side by a 3-to-1 ratio. The most likely azimuthal location of multisystem spectra is about 210° counterclockwise from the heading. In the right-front quarter, waves propagate into the advancing wind field and experience extended air–sea exchanges to grow higher and longer; in the left-rear quarter, they propagate away from the advancing wind field and are more likely younger seas. The radial variation of wave propagation is relatively minor except inside the RMW. A model describing the dominant wave propagation direction is presented. The regression statistics between modeled and measured wave directions show consistent agreement in 9 of the 11 datasets available for investigation. Causes for the significantly different statistics of the two remaining datasets include proximity to coast (a landfalling case) and rapid change in the hurricane translation speed or direction.

scholarly journals Sea Surface Salinity Response to Tropical Cyclones Based on Satellite Observations

2021 ◽  
Vol 13 (3) ◽  
pp. 420
Author(s):  
Jingru Sun ◽  
Gabriel Vecchi ◽  
Brian Soden
Keyword(s):  
Tropical Cyclones ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Translation Speed ◽  
Salinity Stratification ◽  
Left Hand ◽  
In Situ Data ◽  
Salinity Response ◽  
The Right

Multi-year records of satellite remote sensing of sea surface salinity (SSS) provide an opportunity to investigate the climatological characteristics of the SSS response to tropical cyclones (TCs). In this study, the influence of TC winds, rainfall and preexisting ocean stratification on SSS evolution is examined with multiple satellite-based and in-situ data. Global storm-centered composites indicate that TCs act to initially freshen the ocean surface (due to precipitation), and subsequently salinify the surface, largely through vertical ocean processes (mixing and upwelling), although regional hydrography can lead to local departure from this behavior. On average, on the day a TC passes, a strong SSS decrease is observed. The fresh anomaly is subsequently replaced by a net surface salinification, which persists for weeks. This salinification is larger on the right (left)-hand side of the storm motion in the Northern (Southern) Hemisphere, consistent with the location of stronger turbulent mixing. The influence of TC intensity and translation speed on the ocean response is also examined. Despite having greater precipitation, stronger TCs tend to produce longer-lasting, stronger and deeper salinification especially on the right-hand side of the storm motion. Faster moving TCs are found to have slightly weaker freshening with larger area coverage during the passage, but comparable salinification after the passage. The ocean haline response in four basins with different climatological salinity stratification reveals a significant impact of vertical stratification on the salinity response during and after the passage of TCs.

scholarly journals EFFECT OF TRANSLATE SPEED OF TYPHOONS ON WIND WAVES

2020 ◽  
pp. 14
Author(s):  
Naoto Inagaki ◽  
Tomoya Shibayama ◽  
Miguel Esteban ◽  
Tomoyuki Takabatake
Keyword(s):  
Tropical Cyclones ◽  
Empirical Model ◽  
Wind Field ◽  
Meteorological Data ◽  
Wind Waves ◽  
Coupled Model ◽  
Wind Generation ◽  
Translation Speed ◽  
Different Types ◽  
Quantitative Assessments

Quantitative assessments of the effect that changes in the translate speed of typhoons have on wind waves were carried out. A WRF-SWAN coupled model that used observed meteorological data was applied to eight different typhoons in the vicinity of Shiono-Misaki, Japan. The authors proposed a new methodology to modify the translate speed and wind field of tropical cyclones, using an empirical model in which the gross wind field is expressed as the summation of two different types of wind generation (due to either the pressure gradient or translation speed). As a result, it is important to raise awareness of the future problems that can be caused by large storms that stall for prolonged periods of time.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/oCSbyaYoNEc

The Spatial Distribution of Ocean Waves in Tropical Cyclones

2020 ◽  
Vol 50 (8) ◽  
pp. 2123-2139 ◽  
Author(s):  
Ali Tamizi ◽  
Ian R. Young
Keyword(s):  
Tropical Cyclone ◽  
Wave Field ◽  
Tropical Cyclones ◽  
Wind Field ◽  
Ocean Waves ◽  
Peak Frequency ◽  
One Dimensional ◽  
Wind Sea ◽  
The One ◽  
The Right

AbstractThe spatial structure of both the wind and wave fields within tropical cyclones is investigated using two large databases. The first of these was compiled from global overpasses of tropical cyclones by satellite altimeters. The second dataset consists of an extensive collection of North American buoy measurements during the passage of tropical cyclones (hurricanes). The combined datasets confirm the vortex structure of the tropical cyclone wind field with the strongest winds to the right (Northern Hemisphere) of the storm. The wave field largely mirrors the wind field but with greater right–left asymmetry that results from the extended fetch to the right of the translating tropical cyclone. The extensive in situ buoy database confirms previous studies indicating that the one-dimensional spectra are generally unimodal. The directional spectra are, however, directionally skewed, consisting of remotely generated waves radiating out from the center of the storm and locally generated wind sea. The one-dimensional wave spectra have many similarities to fetch-limited cases, although for a given peak frequency the spectra contain less energy than for a fetch-limited case. This result is consistent with the fact that much of the wave field is dominated by remotely generated waves.

La recherche appliquée: le cas du « Katholiek Sociaal Kerkelijk Instituut (KASKI) » aux Pays-Bas

1971 ◽  
Vol 18 (4) ◽  
pp. 621-637 ◽  
Author(s):  
Adolf Holl ◽  
Hyacinthe Crépin
Keyword(s):  
Professional Competence ◽  
Rapid Change ◽  
Religious Life ◽  
Religious Practice ◽  
The Political ◽  
Religious Groups ◽  
The People ◽  
Pastoral Planning ◽  
Senior Research ◽  
The Right

Following Vatican II changes are rapidly taking place within Dutch Catholicism — the bishops no longer make decisions in an authoritarian way: religious practice is de clining ; priests and religious are decreasing in numbers and many religious and pastoral experiments have come into being. KASKI has the responsibility of keeping pace with the Church during this process of change. In order to do this it makes use of several modes of work — the production of statistics relating to the position of religion in Society, the planning of religious and pastoral institutions and the study of new forms of the religious life in orders and congregations. For the first task it has used the same instruments for twenty- five years and the censuses thus produced yield valuable infor mation. As far as pastoral planning is concerned, it works in the field, playing the role of catalyst for those who have to make decisions and the people who have to carry out these decisions. This was the case, for instance, in the pastoral planning of the town of Eindhoven. Finally, when dealing with the new forms of communal religious life it adopts the method of studying through participation so that two of its researchers working in this sector are themselves members of religious groups. Applied research poses important problems, both from the methodological and from the political points of view. Amongst them may be noted the difficulty of determining precisely what constitutes rapid change in religious life, and the political choice of the persons for whom the research is being con ducted; the latter inevitably imposes a certain degree of conformity upon the perspectives of the work. (For example, the choice of the Dutch hierarchy which was to follow the general lines given by a large majority of Catholic opinion when it was tested particularly on questions like the liturgical and parochial changes). The fact, also, that the director of KASKI himself has a personal commitment to what may be described as the « right of centre » position in Dutch Catho licism poses problems for the work of the Institute. Political and religious radicalism is not a strong characteristic of the more senior research workers. KASKI is a rare example of a centre which brings socio logists together and uses their professional competence to accompany change in religious institutions.

The Evolution of Asymmetries in the Tropical Cyclone Boundary Layer Wind Field during Landfall

2021 ◽  
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Wind Field ◽  
Surface Wind ◽  
Frictional Stress ◽  
Homogeneous Surface ◽  
Sudden Decrease ◽  
The Right ◽  
Tropical Cyclone Boundary Layer

Abstract The evolution of the tropical cyclone boundary layer (TCBL) wind field before landfall is examined in this study. As noted in previous studies, a typical TCBL wind structure over the ocean features a supergradient boundary layer jet to the left of motion and Earth-relative maximum winds to the right. However, the detailed response of the wind field to frictional convergence at the coastline is less well known. Here, idealized numerical simulations reveal an increase in the offshore radial and vertical velocities beginning once the TC is roughly 200 km offshore. This increase in the radial velocity is attributed to the sudden decrease in frictional stress once the highly agradient flow crosses the offshore coastline. Enhanced advection of angular momentum by the secondary circulation forces a strengthening of the supergradient jet near the top of the TCBL. Sensitivity experiments reveal that the coastal roughness discontinuity dominates the friction asymmetry due to motion. Additionally, increasing the inland roughness through increasing the aerodynamic roughness length enhances the observed asymmetries. Lastly, a brief analysis of in-situ surface wind data collected during the landfall of three Gulf of Mexico hurricanes is provided and compared to the idealized simulations. Despite the limited in-situ data, the observations generally support the simulations. The results here imply that assumptions about the TCBL wind field based on observations from over horizontally-homogeneous surface types - which have been well-documented by previous studies - are inappropriate for use near strong frictional heterogeneity.

scholarly journals A Discrete Huber-braun Neuron Model: From Nodal Properties to Network Performance

2021 ◽  
Author(s):  
Shaoba He ◽  
Karthikeyan Rajagopal ◽  
Anitha Karthikeyan ◽  
Ashokkumar Sriniva
Keyword(s):  
Wave Propagation ◽  
Network Performance ◽  
Neuron Model ◽  
Coupling Effect ◽  
Single Layer ◽  
Simple Wave ◽  
Spiral Waves ◽  
Neuron Models ◽  
Positive Role ◽  
Multiple Wave

Abstract Many of the well-known neuron models are continuous time systems with complex mathematical definitions. Literatures have shown that a discrete mathematical model can effectively replicate the complete dynamical behaviour of a neuron with much reduced complexity. Hence, we propose a new discrete neuron model derived from the Huber-Braun neuron with two additional slow and subthreshold currents alongside the ion channel currents. We have also introduced temperature dependent ion channels to study its effects on the firing pattern of the neuron. With bifurcation and Lyapunov exponents we showed the chaotic and periodic regions of the discrete model. Further to study the complexity of the neuron model, we have used the sample entropy algorithm. Though the individual neuron analysis gives us an idea about the dynamical properties, it’s the collective behaviour which decides the overall behavioural pattern of the neuron. Hence, we investigate the spatiotemporal behaviour of the discrete neuron model in single- and two-layer network. We have considered noise and obstacles as the two important factor which changes the excitability of the neurons in the network. When there is no noise or obstacle, the network display simple wave propagation with highly excitable neurons. Literatures have shown that spiral waves can play a positive role in breaking through quiescent areas of the brain as a pacemaker by creating a coherence resonance behaviour. Hence, we are interested in studying the induced spiral waves in the network. In this condition when an obstacle is introduced the wave propagation is disturbed and we could see multiple wave re-entry and spiral waves. Now when we consider only noise with no obstacle, for selected noise variances the network supports wave re-entry. By introducing an obstacle in this noisy network, the re-entry soon disappears, and the network soon enters idle state with no resetting. In a two-layer network when the obstacle is considered only in one layer and stimulus applied to the layer having the obstacle, the wave re-entry is seen in both the layer though the other layer is not exposed to obstacle. But when both the layers are inserted with an obstacle and stimuli also applied to the layers, they behave like independent layers with no coupling effect. This in a two-layer network stimulus play an important role in spatiotemporal dynamics of the network. Similar noise effects like the single layer network are also seen in the two-layer network.

scholarly journals Oxygen transport and release of adenosine triphosphate in micro-channels

2015 ◽  
Author(s):  
Terry Moschandreou
Keyword(s):  
Oxygen Transport ◽  
Rapid Change ◽  
Microfluidic Channel ◽  
Permeable Membrane ◽  
Micro Channels ◽  
Free Region ◽  
Method Of Solution ◽  
Channel Tube ◽  
A Cell ◽  
The Right

The governing nonlinear steady equations for oxygen transport in a microfluidic channel are solved analytically. The Lagrange inversion theorem is used which admits complete integrable solutions in the channel. Considering a cell-rich and cell free region with RBCs and blood plasma, we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. The method of solution is compared to numerical results. The analytical results obtained could prove useful for the corresponding time dependent problem in future studies.

Wave Propagation in the Linear Theory of Elastic Shells

1976 ◽  
Vol 43 (2) ◽  
pp. 281-285 ◽  
Author(s):  
H. Cohen
Keyword(s):  
Wave Propagation ◽  
Circular Cylinder ◽  
Linear Theory ◽  
Wave Mode ◽  
Mode Shapes ◽  
Elastic Shells ◽  
Special Cases ◽  
Cosserat Surface ◽  
Singular Wave ◽  
The Right

The problem of wave propagation in elastic shells within the framework of a linear theory of a Cosserat surface is treated using the method of singular wave curves. The equations for determining the speeds of propagation and their associated wave mode shapes are obtained in a form involving the speeds of propagation in Cosserat plates and the curvature of the shell. A number of special cases in which the speeds and mode shapes simplify are considered. In particular, these special cases are shown to include as examples, certain systems of waves in elastic shells whose middle surfaces are the surface of revolution, the circular cylinder, the sphere, and the right helicoid.

scholarly journals Wave Glider Observations of Surface Waves During Three Tropical Cyclones in the South China Sea

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1331 ◽  
Author(s):  
Di Tian ◽  
Han Zhang ◽  
Wenyan Zhang ◽  
Feng Zhou ◽  
Xiujun Sun ◽  
...  
Keyword(s):  
Surface Wave ◽  
South China Sea ◽  
Surface Waves ◽  
Tropical Cyclones ◽  
South China ◽  
Tangential Direction ◽  
China Sea ◽  
Wave Forecast ◽  
Wave Glider ◽  
The Right

Surface waves induced by tropical cyclones (TCs) play an important role in the air–sea interaction, yet are seldom observed. In the 2017 summer, a wave glider in the northern South China Sea successfully acquired the surface wave parameters when three TCs (Hato, Pakhar, and Mawar) passed though successively. During the three TCs, surface wave period increased from 4–6 s to ~8–10 s and surface wave height increased from 0–1 m to 3–8 m. The number of wave crests observed in a time interval of 1024 s decreased from 100–150 to 60–75. The sea surface roughness, a key factor in determining the momentum transfer between air and sea, increased rapidly during Hato, Pakhar, and Mawar. Surface waves rotated clockwise (anti-clockwise) on the right (left) side of the TC track, and generally propagated to the right side of the local cyclonic tangential direction relative to the TC center. The azimuthal dependence of the wave propagation direction is close to sinusoidal in a region within 50–600 km. The intersection angle between surface wave direction and the local cyclonic tangential direction is generally smallest in the right-rear quadrant of the TC and tends to be largest in the left-rear quadrant. This new set of glider wave observational data proves to be useful for assessing wave forecast products and for improvements in corresponding parameterization schemes.

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