scholarly journals Momentum flux, energy flux and pressure drag associated with mountain wave across western ghat

MAUSAM ◽  
2021 ◽  
Vol 52 (2) ◽  
pp. 325-332
Author(s):  
SOMENATH DUTTA
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Momentum Flux ◽  
Western Ghat ◽  
Mountain Wave ◽  
Pressure Drag ◽  
Wave Energy Flux ◽  
Vertically Propagating ◽  
Flux Energy ◽  
Wave Momentum

An attempt has been made to parameterize the wave momentum flux wave energy flux and pressure drag associated with mountain wave across the Mumbai-Pune section of western ghat mountain in India.   A two dimensional frictionless, adiabatic, hydrostatic, Boussinesq flow with constant basic flow (U) and constant Brunt Vaisala frequency (N) across a mesoscale mountain with infinite extension in the Cross wind direction, has been considered here.   It has been shown that for a vertically propagating (or decaying) waves the wave momentum flux is downward (or upward) and the wave energy flux is upward (or downward). It has also been shown that both the fluxes are independent of the half width of the bell shaped part of the western ghat. The analytically derived formula have been used to compute the pressure drag and to find out the vertical profile of wave momentum flux and wave energy flux for different cases of mountain wave across western ghat, as reported by earlier workers.

scholarly journals KEBENCANAAN GEOLOGI KELAUTAN DI BAGIAN UTARA PULAU OBI, MALUKU

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Nineu Yayu Geurhaneu ◽  
Fauzi Budi Prasetio ◽  
Godwin Latuputty
Keyword(s):  
Energy Flux ◽  
Water Depth ◽  
Wave Energy ◽  
Secondary Data ◽  
Primary Data ◽  
Depth Range ◽  
Geological Hazard ◽  
Characteristic Mapping ◽  
Wave Energy Flux ◽  
Flux Energy

Lokasi penelitian terletak di bagian utara pulau Obi, Maluku. Tujuan penelitian ini adalah untuk mengkaji aspek kebencanaan geologi kelautan berupa pengumpulan data primer dan sekunder. Data primer meliputi hasil pengukuran kedalaman dan pemetaan karakteristik pantai. Data sekunder berupa energi gelombang yang dihitung melalui pendekatan energi fluks dari data angin di stasiun pengamatan Labuha/Taliabu tahun 2004 – 2013. Hasil penelitian berupa peta karakteristik pantai dan peta batimetri. Kedalaman daerah penelitian berkisar dari 0 sampai 310 meter dan perairan terdalam terletak di antara Pulau Obi dan Pulau Bisa. Kebencanaan geologi di Pulau Obi berupa banjir bandang, abrasi pantai dan tsunami.Kata kunci : kebencanaan geologi, energi fluks, banjir bandang, abrasi pantai dan tsunami, Pulau ObiThe study area is located on northern part of  Obi Island, Moluccas.  The research objective is to determine the potential of marine geological hazard by primary and secondary data collecting. Primary data consists of bathymetric and coastal characteristic mapping. Secondary data is from calculated wave energy flux by using wind data from Labuha / Taliabu observation stations (2004 – 2013). The result composed of coastal characteristic and bathymetric maps. The water depth range from 0 to 310 metres and the deepest part in between Obi and Bisa islands. The geological hazard on Obi Island consist of  flooding,coastal abrasion and tsunami.Keywords :  geological hazard, flux energy, flooding, coastal abrasion and tsunami, Obi Island

The Influence of Vertical Wind Shear on the Evolution of Mountain-Wave Momentum Flux

2019 ◽  
Vol 76 (3) ◽  
pp. 749-756 ◽  
Author(s):  
Dale R. Durran ◽  
Maximo Q. Menchaca
Keyword(s):  
Momentum Flux ◽  
Large Scale ◽  
Vertical Wind Shear ◽  
Vertical Shear ◽  
Mean Flow ◽  
Mountain Wave ◽  
Flow Acceleration ◽  
Momentum Fluxes ◽  
Vertically Propagating ◽  
Wave Momentum

Abstract The influence of vertical shear on the evolution of mountain-wave momentum fluxes in time-varying cross-mountain flows is investigated by numerical simulation and analyzed using ray tracing and the WKB approximation. The previously documented tendency of momentum fluxes to be strongest during periods of large-scale cross-mountain flow acceleration can be eliminated when the cross-mountain wind increases strongly with height. In particular, the wave packet accumulation mechanism responsible for the enhancement of the momentum flux during periods of cross-mountain flow acceleration is eliminated by the tendency of the vertical group velocity to increase with height in a mean flow with strong forward shear, thereby promoting vertical separation rather than concentration of vertically propagating wave packets.

scholarly journals The vertical structure of annual wave energy flux in the tropical Indian Ocean

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Zimeng Li ◽  
Hidenori Aiki ◽  
Motoki Nagura ◽  
Tomomichi Ogata
Keyword(s):  
Indian Ocean ◽  
Energy Flux ◽  
Wave Energy ◽  
Tropical Indian Ocean ◽  
Ocean Model ◽  
Model Driven ◽  
Propagating Waves ◽  
Wave Energy Flux ◽  
Vertically Propagating ◽  
Stratified Ocean

AbstractA recently developed energy flux diagnosis scheme, which incorporates a smooth connection between the tropical and subtropical zones, is used in the present study to investigate vertically propagating waves in the tropical Indian Ocean (IO) based on the result of a linear, continuously stratified ocean model driven by climatological wind forcing. This extended diagnosis reveals deep-reaching eastward energy fluxes at the equator which develop four times per year and are associated with equatorial Kelvin waves (KWs) generated by semiannual winds. The authors find that the downward transfer of wave energy is particularly deep in the southern Bay of Bengal (SBoB). This downward flux is attributed to off-equatorial Rossby waves and appears four times per year, maximizing its amplitude during November–December. Southwesterly winds in the Arabian Sea intensify eastward energy flux of KWs at mid-depth, which maximizes in amplitude in August. This is contrastive to KW energy flux at the surface which peaks in May. These mid-depth equatorial KW packets subsequently arrive at the eastern boundary of the IO and are diffracted poleward to produce downward energy flux in November and December detected in the SBoB.

scholarly journals PROSES AKRASI DAN ABRASI BERDASARKAN PEMETAAN KARAKTERISTIK PANTAI DAN DATA GELOMBANG DI TELUK PELABUHAN RATU DAN CILETUH, KABUPATEN SUKABUMI, JAWA BARAT

2016 ◽  
Vol 13 (1) ◽  
Author(s):  
Deny Setiady ◽  
Lili Sarmili
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Coastal Sediments ◽  
Longshore Current ◽  
West Java ◽  
Wave Energy Flux ◽  
Flux Energy

Lokasi Penelitian dilakukan di teluk Pelabuhan Ratu dan Teluk Ciletuh, Kabupaten Sukabumi, Provinsi Jawa Barat. Tujuan penelitian adalah untuk mengetahui karakteristik pantai dan hubungannya dengan akrasi dan abrasi berdasarkan energi flux. Metode penelitian terdiri dari penentuan posisi, karakteristik pantai, pengambilan sampel sedimen pantai, dan analisis gelombang. Proses abrasi dan akrasi di daerah penelitian erat kaitannya dengan besar kecilnya energi gelombang. Energi gelombang merupakan salah satu komponen dari arus sejajar pantai. Berdasarkan karakteristik pantai, tipe pantai terdiri dari : (1) Daerah perbukitan terjal, (2) Daerah perbukitan bergelombang, dan (3) Daerah dataran rendah. Analisis energi flux gelombang menunjukkan bahwa proses abrasi terjadi dititik tinjau 2 ke 3, 4 ke 5, 6 ke 8, 10 ke 11, 14 ke 15, dan 16 ke 17, sedangkan proses akrasi terjadi di titik tinjau 3 ke 4, 5 ke 6, 8 ke 10, 11 ke 13, 15 ke 16, 17 ke 18, dan 20 ke 21.Kata Kunci: Akrasi, abrasi, karakteristik pantai, energi flux, Pantai Pelabuhan Ratu. Location of the study at Pelabuhan Ratu and Ciletuh bays, Sukabumi of West Java Province. The aim of study is to map the coastal charectristics in relation to accretion and abrasion processes based on wave energy flux. The method consists of navigation, coastal characteristics, coastal sediments samples and wave analyses. The abrasion and accresion processes are closely related to how big the wave energy. Wave energy is one of longshore current components. Based on the coastal characteristics, the coastal types can be divided into : (1) steep hills (2) undulating hills, and (3) lowland. Wave energy flux shows that abrasion processes occur from the point of 2 to 3, 4 to 5, 6 to 8, 10 to 11, 14 to 15, and 16 to 17, while for accretion processes occur from the point of 3 to 4, 5 to 6, 8 to 10, 11 to 13, 15 to 16, 17 to 18, and 20 to 21. Keywords: acrasion, abrasion, coastal characteristic, flux energy, Pelabuhan Ratu coast

Mountain-Wave Momentum Flux in an Evolving Synoptic-Scale Flow

2005 ◽  
Vol 62 (9) ◽  
pp. 3213-3231 ◽  
Author(s):  
Chih-Chieh Chen ◽  
Dale R. Durran ◽  
Gregory J. Hakim
Keyword(s):  
Numerical Simulations ◽  
Momentum Flux ◽  
Nonlinearity Parameter ◽  
Synoptic Scale ◽  
Incident Flow ◽  
Mountain Wave ◽  
Pressure Drag ◽  
Momentum Fluxes ◽  
Wave Induced ◽  
Wave Momentum

Abstract The evolution of mountain-wave-induced momentum flux is examined through idealized numerical simulations during the passage of a time-evolving synoptic-scale flow over an isolated 3D mountain of height h. The dynamically consistent synoptic-scale flow U accelerates and decelerates with a period of 50 h; the maximum wind arrives over the mountain at 25 h. The synoptic-scale static stability N is constant, so the time dependence of the nonlinearity parameter, ɛ(t) = Nh/U(t), is symmetric about a minimum value at 25 h. The evolution of the vertical profile of momentum flux shows substantial asymmetry about the midpoint of the cycle even though the nonlinearity parameter is symmetric. Larger downward momentum fluxes are found during the accelerating phase, and the largest momentum fluxes occur in the mid- and upper troposphere before the maximum background flow arrives at the mountain. For a period of roughly 15 h, this vertical distribution of momentum flux accelerates the lower-tropospheric zonal-mean winds due to low-level momentum flux convergence. Conservation of wave action and Wentzel–Kramers–Brillouin (WKB) ray tracing are used to reconstruct the time–altitude dependence of the mountain-wave momentum flux in a semianalytic procedure that is completely independent of the full numerical simulations. For quasi-linear cases, the reconstructions show good agreement with the numerical simulations, implying that the basic asymmetry obtained in the full numerical simulations may be interpreted using WKB theory. These results demonstrate that even slow variations in the mean flow, with a time scale of 2 days, play a dominant role in regulating the vertical profile of mountain-wave-induced momentum flux. The time evolution of cross-mountain pressure drag is also examined in this study. For almost-linear cases, the pressure drag is well predicted under steady-state linear theory by using the instantaneous incident flow. Nevertheless, for mountains high enough to preserve a moderate degree of nonlinearity when the synoptic-scale incident flow is strongest, the evolution of cross-mountain pressure drag is no longer symmetric about the time of maximum wind. A higher drag state is found when the cross-mountain flow is accelerating. These results suggest that the local character of the topographically induced disturbance cannot be solely determined by the instantaneous value of the nonlinearity parameter ɛ.

scholarly journals Joint Modelling of Wave Energy Flux and Wave Direction

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 460
Author(s):  
Takvor H. Soukissian ◽  
Flora E. Karathanasi
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Goodness Of Fit ◽  
North Atlantic Ocean ◽  
Wave Climate ◽  
Western Mediterranean ◽  
Wave Direction ◽  
Bivariate Model ◽  
The North ◽  
Wave Energy Flux

In the context of wave resource assessment, the description of wave climate is usually confined to significant wave height and energy period. However, the accurate joint description of both linear and directional wave energy characteristics is essential for the proper and detailed optimization of wave energy converters. In this work, the joint probabilistic description of wave energy flux and wave direction is performed and evaluated. Parametric univariate models are implemented for the description of wave energy flux and wave direction. For wave energy flux, conventional, and mixture distributions are examined while for wave direction proven and efficient finite mixtures of von Mises distributions are used. The bivariate modelling is based on the implementation of the Johnson–Wehrly model. The examined models are applied on long-term measured wave data at three offshore locations in Greece and hindcast numerical wave model data at three locations in the western Mediterranean, the North Sea, and the North Atlantic Ocean. A global criterion that combines five individual goodness-of-fit criteria into a single expression is used to evaluate the performance of bivariate models. From the optimum bivariate model, the expected wave energy flux as function of wave direction and the distribution of wave energy flux for the mean and most probable wave directions are also obtained.

Horizontal energy flux of wind-driven intraseasonal waves in the tropical Atlantic by a unified diagnosis

2021 ◽  
Author(s):  
Qingyang Song ◽  
Hidenori Aiki
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Horizontal Distribution ◽  
Kelvin Waves ◽  
Asymmetric Distribution ◽  
Central Basin ◽  
Tropical Atlantic ◽  
Equatorial Wave ◽  
Wave Energy Flux ◽  
Velocity Anomalies

AbstractIntraseasonal waves in the tropical Atlantic Ocean have been found to carry prominent energy that affects interannual variability of zonal currents. This study investigates energy transfer and interaction of wind-driven intraseasonal waves using single-layer model experiments. Three sets of wind stress forcing at intraseasonal periods of around 30 days, 50 days and 80 days with a realistic horizontal distribution are employed separately to excite the second baroclinic mode in the tropical Atlantic. A unified scheme for calculating the energy flux, previously approximated and used for the diagnosis of annual Kelvin and Rossby waves, is utilized in the present study in its original form for intraseasonal waves. Zonal velocity anomalies by Kelvin waves dominate the 80-day scenario. Meridional velocity anomalies by Yanai waves dominate the 30-day scenario. In the 50-day scenario, the two waves have comparable magnitudes. The horizontal distribution of wave energy flux is revealed. In the 30-day and 50-day scenarios, a zonally alternating distribution of cross-equatorial wave energy flux is found. By checking an analytical solution excluding Kelvin waves, we confirm that the cross-equatorial flux is caused by the meridional transport of geopotential at the equator. This is attributed to the combination of Kelvin and Yanai waves and leads to the asymmetric distribution of wave energy in the central basin. Coastally-trapped Kelvin waves along the African coast are identified by along-shore energy flux. In the north, the bend of the Guinea coast leads the flux back to the equatorial basin. In the south, the Kelvin waves strengthened by local wind transfer the energy from the equatorial to Angolan regions.

scholarly journals Another Note on Rossby Wave Energy Flux

2020 ◽  
Vol 50 (2) ◽  
pp. 531-534
Author(s):  
Theodore S. Durland ◽  
J. Thomas Farrar
Keyword(s):  
Group Velocity ◽  
Energy Flux ◽  
Rossby Wave ◽  
Wave Energy ◽  
Energy Equation ◽  
Divergent Part ◽  
Pressure Work ◽  
Wave Energy Flux ◽  
The Difference ◽  
Definition Of

AbstractLonguet-Higgins in 1964 first pointed out that the Rossby wave energy flux as defined by the pressure work is not the same as that defined by the group velocity. The two definitions provide answers that differ by a nondivergent vector. Longuet-Higgins suggested that the problem arose from ambiguity in the definition of energy flux, which only impacts the energy equation through its divergence. Numerous authors have addressed this issue from various perspectives, and we offer one more approach that we feel is more succinct than previous ones, both mathematically and conceptually. We follow the work described by Cai and Huang in 2013 in concluding that there is no need to invoke the ambiguity offered by Longuet-Higgins. By working directly from the shallow-water equations (as opposed to the more involved quasigeostrophic treatment of Cai and Huang), we provide a concise derivation of the nondivergent pressure work and demonstrate that the two energy flux definitions are equivalent when only the divergent part of the pressure work is considered. The difference vector comes from the nondivergent part of the geostrophic pressure work, and the familiar westward component of the Rossby wave group velocity comes from the divergent part of the geostrophic pressure work. In a broadband wave field, the expression for energy flux in terms of a single group velocity is no longer meaningful, but the expression for energy flux in terms of the divergent pressure work is still valid.

scholarly journals Probabilistic forecasting of the wave energy flux

2012 ◽  
Vol 93 ◽  
pp. 364-370 ◽  
Author(s):  
P. Pinson ◽  
G. Reikard ◽  
J.-R. Bidlot
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Probabilistic Forecasting ◽  
Wave Energy Flux
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