Tail effects in the third post-Newtonian gravitational wave energy flux of compact binaries in quasi-elliptical orbits

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.

Download Full-text

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

Journal of Physical Oceanography ◽

10.1175/jpo-d-20-0262.1 ◽

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.

Download Full-text

Virgo and Gravitational-Wave Computing in Europe

EPJ Web of Conferences ◽

10.1051/epjconf/202024507050 ◽

2020 ◽

Vol 245 ◽

pp. 07050

Author(s):

Stefano Bagnasco

Keyword(s):

Gravitational Wave ◽

Current Status ◽

Low Latency ◽

Observational Period ◽

Compact Binaries ◽

The Third ◽

Compact Binary ◽

Continuous Waves ◽

The Us ◽

Wave Event

Advanced Virgo is an interferometer for the detection of gravitational waves at the European Gravitational Observatory in Italy. Along with the two Advanced LIGO interferometers in the US, Advanced Virgo is being used to collect data from astrophysical sources such as compact binary coalescences and is currently running the third observational period, collecting gravitational wave event candidates at a rate of more than once per week. Data from the interferometer are processed by running search pipelines for several expected signals, from coalescing compact binaries to continuous waves and burst events. Furthermore, detector characterisation studies are run. Some of the processing needs to be done with low latency, to be able to provide triggers for other observatories and make multi-messenger observations possible. Deep searches are run offline on external computing centres. Thus, data needs also to be reliably and promptly distributed from the EGO site to computer centres in Europe and the US for further analysis and archival storage. Two of the defining characteristics of Virgo computing are the heterogeneity of the activities and the need to interoperate with LIGO. A very wide array of analysis pipelines differing in scientific target, implementation details and running environment assumptions have to be allowed to run ubiquitously and uniformly on dedicated resources and, in perspective, on heterogeneous infrastructures. The current status, possible strategies and outlook of Virgo computing are discussed.

Download Full-text

Another Note on Rossby Wave Energy Flux

Journal of Physical Oceanography ◽

10.1175/jpo-d-19-0237.1 ◽

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.

Download Full-text

Probabilistic forecasting of the wave energy flux

Applied Energy ◽

10.1016/j.apenergy.2011.12.040 ◽

2012 ◽

Vol 93 ◽

pp. 364-370 ◽

Cited By ~ 57

Author(s):

P. Pinson ◽

G. Reikard ◽

J.-R. Bidlot

Keyword(s):

Energy Flux ◽

Wave Energy ◽

Probabilistic Forecasting ◽

Wave Energy Flux

Download Full-text