scholarly journals Tidal and near-inertial internal waves over the Reykjanes Ridge

2020 ◽  
Author(s):  
Clément Vic ◽  
Bruno Ferron ◽  
Virginie Thierry ◽  
Herlé Mercier ◽  
Pascale Lherminier
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Time Scales ◽  
Internal Waves ◽  
Phase Locking ◽  
Tidal Energy ◽  
Kinetic Energy Density ◽  
Energy Fluxes ◽  
Reykjanes Ridge ◽  
Inertial Energy

AbstractInternal waves in the semi-diurnal and near-inertial bands are investigated using an array of seven moorings located over the Reykjanes Ridge in a cross-ridge direction (57.6-59.1°N, 28.5-33.3°W). Continuous measurements of horizontal velocity and temperature for more than two years allow us to estimate the kinetic energy density and the energy fluxes of the waves. We found that there is a remarkable phase locking and linear relationship between the semi-diurnal energy density and the tidal energy conversion at the spring-neap cycle. The energy-to-conversion ratio gives replenishment time scales of 4-5 days on the ridge top vs 7-9 days on the flanks. Altogether, these results demonstrate that the bulk of the tidal energy on the ridge comes from near local sources, with a redistribution of energy from the top to the flanks, which is endorsed by the energy fluxes oriented in the cross-ridge direction. Implications for tidally-driven energy dissipation are discussed. The time-averaged near-inertial kinetic energy is smaller than the semi-diurnal kinetic energy by a factor 2-3, but is much more variable in time. It features a strong seasonal cycle with a winter intensification and sub-seasonal peaks associated with local wind bursts. The ratio of energy to wind work gives replenishment time scales of 13-15 days, which is consistent with the short time scales of observed variability of near-inertial energy. Finally, in the upper ocean (1 km), the highest levels of near-inertial energy are preferentially found in anticyclonic structures, with a twofold increase compared to cyclonic structures, illustrating the funneling effect of anticyclones.

Tidal and near-inertial energy density and energy fluxes over the Reykjanes Ridge

2020 ◽  
Author(s):  
Clément Vic ◽  
Bruno Ferron ◽  
Ivane Salaün ◽  
Virginie Thierry ◽  
Herlé Mercier
Keyword(s):  
Energy Density ◽  
Water Mass ◽  
Internal Tide ◽  
Meridional Overturning Circulation ◽  
Lower Limbs ◽  
Energy Fluxes ◽  
Seafloor Topography ◽  
Reykjanes Ridge ◽  
Inertial Energy ◽  
Water Mass Transformation

<p>The Reykjanes Ridge is a key topographic structure stretching south of Iceland and located at the crossroad of the Atlantic Meridional Overturning Circulation upper and lower limbs. It has been inferred to host significant mixing and water mass transformation, yet the mechanisms at play remain obscure. Using data from an array of 7 moorings deployed for two years over the Reykjanes Ridge in a cross-ridge direction, we computed internal waves’ energy density and energy fluxes in the dominating wavebands, i.e., near-inertial and semi-diurnal (tidal) bands to assess the contribution of several mechanisms at fuelling a route to energy dissipation and mixing. Internal tide fluxes are dominating the energy fluxes by an order of magnitude right on top of the ridge and follow a clear spring-neap cycle; but rapidly fade away and become decoherent O(100) km away from the ridge, suggesting a strong scattering by mesoscale turbulence and seafloor topography. Near-inertial energy fluxes and density are surface-intensified and follow a seasonal cycle, with a winter intensification due to storms and intense low-pressure weather systems. The level of near-inertial energy density is roughly explained by the local wind power input, and rapid decay of energy with depth suggests that most of the dissipation occurs in the surface layers, thus is not important for deep water mass transformation.<span> </span></p>

scholarly journals Pulsations of blue supergiants before and after helium core ignition

2013 ◽  
Vol 9 (S301) ◽  
pp. 321-324
Author(s):  
Jakub Ostrowski ◽  
Jadwiga Daszyńska-Daszkiewicz
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Kinetic Energy Density ◽  
Low Degree ◽  
Before And After

AbstractWe present results of pulsation analyses of B-type supergiant models with masses of 14 – 18 M⊙, considering evolutionary stages before and after helium core ignition. Using a non-adiabatic pulsation code, we compute instability domains for low-degree modes. For selected models in these two evolutionary phases, we compare properties of pulsation modes. Significant differences are found in oscillation spectra and the kinetic energy density of pulsation modes.

scholarly journals Anisotropy of the field-induced kinetic energy density in Bi2212

2014 ◽  
Vol 433 ◽  
pp. 79-83 ◽  
Author(s):  
J.P. Peña ◽  
R.R. da Silva ◽  
P. Pureur
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Kinetic Energy Density

scholarly journals libKEDF: An accelerated library of kinetic energy density functionals

2017 ◽  
Vol 38 (17) ◽  
pp. 1552-1559 ◽  
Author(s):  
Johannes M. Dieterich ◽  
William C. Witt ◽  
Emily A. Carter
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Kinetic Energy Density ◽  
Density Functionals

scholarly journals Diurnal Dynamics of the Umov Kinetic Energy Density Vector in the Atmospheric Boundary Layer from Minisodar Measurements

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1347
Author(s):  
Alexander Potekaev ◽  
Nikolay Krasnenko ◽  
Liudmila Shamanaeva
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Energy Flux ◽  
Wind Effect ◽  
Kinetic Energy Density ◽  
Near Surface ◽  
Density Vector ◽  
The Mean ◽  
Umov Vector

The diurnal hourly dynamics of the kinetic energy flux density vector, called the Umov vector, and the mean and turbulent components of the kinetic energy are estimated from minisodar measurements of wind vector components and their variances in the lower 200-meter layer of the atmosphere. During a 24-hour period of continuous minisodar observations, it was established that the mean kinetic energy density dominated in the surface atmospheric layer at altitudes below ~50 m. At altitudes from 50 to 100 m, the relative contributions of the mean and turbulent wind kinetic energy densities depended on the time of the day and the sounding altitude. At altitudes below 100 m, the contribution of the turbulent kinetic energy component is small, and the ratio of the turbulent to mean wind kinetic energy components was in the range 0.01–10. At altitudes above 100 m, the turbulent kinetic energy density sharply increased, and the ratio reached its maximum equal to 100–1000 at altitudes of 150–200 m. A particular importance of the direction and magnitude of the wind effect, that is, of the direction and magnitude of the Umov vector at different altitudes was established. The diurnal behavior of the Umov vector depended both on the time of the day and the sounding altitude. Three layers were clearly distinguished: a near-surface layer at altitudes of 5–15 m, an intermediate layer at altitudes from 15 m to 150 m, and the layer of enhanced turbulence above. The feasibility is illustrated of detecting times and altitudes of maximal and minimal wing kinetic energy flux densities, that is, time periods and altitude ranges most and least favorable for flights of unmanned aerial vehicles. The proposed novel method of determining the spatiotemporal dynamics of the Umov vector from minisodar measurements can also be used to estimate the effect of wind on high-rise buildings and the energy potential of wind turbines.

Orbital-free kinetic-energy density functionals with a density-dependent kernel

1999 ◽  
Vol 60 (24) ◽  
pp. 16350-16358 ◽  
Author(s):  
Yan Alexander Wang ◽  
Niranjan Govind ◽  
Emily A. Carter
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Kinetic Energy Density ◽  
Density Functionals ◽  
Density Dependent ◽  
Orbital Free
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