scholarly journals Role of Mixed‐Layer Instabilities in the Seasonal Evolution of Eddy Kinetic Energy Spectra in a Global Submesoscale Permitting Simulation

2021 ◽  
Vol 48 (18) ◽  
Author(s):  
Hemant Khatri ◽  
Stephen M. Griffies ◽  
Takaya Uchida ◽  
Han Wang ◽  
Dimitris Menemenlis
Keyword(s):  
Kinetic Energy ◽  
Mixed Layer ◽  
Eddy Kinetic Energy ◽  
Energy Spectra ◽  
Seasonal Evolution

scholarly journals On the Role of Asymmetric Convective Bursts to the Problem of Hurricane Intensification: Radiation of Vortex Rossby Waves and Wave–Mean Flow Interactions

2014 ◽  
Vol 71 (6) ◽  
pp. 2057-2077 ◽  
Author(s):  
Konstantinos Menelaou ◽  
M. K. Yau
Keyword(s):  
Kinetic Energy ◽  
Thermal Anomaly ◽  
Eddy Kinetic Energy ◽  
Intensity Change ◽  
Mean Flow ◽  
Symmetric Flow ◽  
Thermal Forcing ◽  
Sensitivity Experiments ◽  
Flow Interactions

Abstract The role of asymmetric convection to the intensity change of a weak vortex is investigated with the aid of a “dry” thermally forced model. Numerical experiments are conducted, starting with a weak vortex forced by a localized thermal anomaly. The concept of wave activity, the Eliassen–Palm flux, and eddy kinetic energy are then applied to identify the nature of the dominant generated waves and to diagnose their kinematics, structure, and impact on the primary vortex. The physical reasons for which disagreements with previous studies exist are also investigated utilizing the governing equation for potential vorticity (PV) perturbations and a number of sensitivity experiments. From the control experiment, it is found that the response of the vortex is dominated by the radiation of a damped sheared vortex Rossby wave (VRW) that acts to accelerate the symmetric flow through the transport of angular momentum. An increase of the kinetic energy of the symmetric flow by the VRW is shown also from the eddy kinetic energy budget. Additional tests performed on the structure and the magnitude of the initial thermal forcing confirm the robustness of the results and emphasize the significance of the wave–mean flow interaction to the intensification process. From the sensitivity experiments, it is found that for a localized thermal anomaly, regardless of the baroclinicity of the vortex and the radial and vertical gradients of the thermal forcing, the resultant PV perturbation follows a damping behavior, thus suggesting that deceleration of the vortex should not be expected.

An Eddy Kinetic Energy View of Physical and Dynamical Processes in Distinct Forecast Scenarios for the Extratropical Transition of Two Tropical Cyclones*

2014 ◽  
Vol 142 (8) ◽  
pp. 2751-2771 ◽  
Author(s):  
Julia H. Keller ◽  
Sarah C. Jones ◽  
Patrick A. Harr
Keyword(s):  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Tropical Cyclones ◽  
Wave Pattern ◽  
Eddy Kinetic Energy ◽  
Ensemble Prediction ◽  
Extratropical Transition ◽  
Ensemble Prediction System ◽  
Development Scenarios

Abstract The extratropical transition (ET) of Hurricane Hanna (2008) and Typhoon Choi-Wan (2009) caused a variety of forecast scenarios in the European Centre for Medium-Range Weather Forecasts (ECMWF) Ensemble Prediction System (EPS). The dominant development scenarios are extracted for two ensemble forecasts initialized prior to the ET of those tropical storms, using an EOF and fuzzy clustering analysis. The role of the transitioning tropical cyclone and its impact on the midlatitude flow in the distinct forecast scenarios is examined by conducting an analysis of the eddy kinetic energy budget in the framework of downstream baroclinic development. This budget highlights sources and sinks of eddy kinetic energy emanating from the transitioning tropical cyclone or adjacent upstream midlatitude flow features. By comparing the budget for several forecast scenarios for the ET of each of the two tropical cyclones, the role of the transitioning storms on the development in downstream regions is investigated. Distinct features during the interaction between the tropical cyclone and the midlatitude flow turned out to be important. In the case of Hurricane Hanna, the duration of baroclinic conversion from eddy available potential into eddy kinetic energy was important for the amplification of the midlatitude wave pattern and the subsequent reintensification of Hanna as an extratropical cyclone. In the case of Typhoon Choi-Wan, the phasing between the storm and the midlatitude flow was one of the most critical factors for the future development.

Mesoscale Energy Spectra of Moist Baroclinic Waves

2013 ◽  
Vol 70 (4) ◽  
pp. 1242-1256 ◽  
Author(s):  
Michael L. Waite ◽  
Chris Snyder
Keyword(s):  
Kinetic Energy ◽  
Physical Space ◽  
Energy Spectra ◽  
Inertial Subrange ◽  
Latent Heating ◽  
Baroclinic Waves ◽  
Rotational Part ◽  
Divergence Field ◽  
Moist Processes

Abstract The role of moist processes in the development of the mesoscale kinetic energy spectrum is investigated with numerical simulations of idealized moist baroclinic waves. Dry baroclinic waves yield upper-tropospheric kinetic energy spectra that resemble a −3 power law. Decomposition into horizontally rotational and divergent kinetic energy shows that the divergent energy has a much shallower spectrum, but its amplitude is too small to yield a characteristic kink in the total spectrum, which is dominated by the rotational part. The inclusion of moist processes energizes the mesoscale. In the upper troposphere, the effect is mainly in the divergent part of the kinetic energy; the spectral slope remains shallow (around −) as in the dry case, but the amplitude increases with increasing humidity. The divergence field in physical space is consistent with inertia–gravity waves being generated in regions of latent heating and propagating throughout the baroclinic wave. Buoyancy flux spectra are used to diagnose the scale at which moist forcing—via buoyant production from latent heating—injects kinetic energy. There is significant input of kinetic energy in the mesoscale, with a peak at scales of around 800 km and a plateau at smaller scales. If the latent heating is artificially set to zero at some time, the enhanced divergent kinetic energy decays over several days toward the level obtained in the dry simulation. The effect of moist forcing of mesoscale kinetic energy presents a challenge for theories of the mesoscale spectrum based on the idealization of a turbulent inertial subrange.

scholarly journals Hadronic jet models today

2010 ◽  
Vol 6 (S275) ◽  
pp. 59-67 ◽  
Author(s):  
Marek Sikora
Keyword(s):  
Kinetic Energy ◽  
Crucial Role ◽  
High Energy ◽  
Matter Content ◽  
Energy Spectra ◽  
Synchrotron Emission ◽  
Relativistic Jets ◽  
Electrons And Positrons ◽  
Adiabatic Cooling

AbstractThe matter content of relativistic jets in AGNs is dominated by a mixture of protons, electrons, and positrons. During dissipative events these particles tap a significant portion of the internal and/or kinetic energy of the jet and convert it into electromagnetic radiation. While leptons – even those with only mildly relativistic energies – can radiate efficiently, protons need to be accelerated up to energies exceeding 1016–19 eV to dissipate radiatively a significant amount of energy via either trigerring pair cascades or direct synchrotron emission. Here I review various constraints imposed on the role of hadronic non-adiabatic cooling processes in shaping the high energy spectra of blazars. It will be argued that protons, despite being efficiently accelerated and presumably playing a crucial role in jet dynamics and dissipation of the jet kinetic energy to the internal energy of electrons and positrons, are more likely to remain radiatively passive in AGN jets.

Kinetic energy spectra of divergent wind in the atmosphere

Tellus ◽  
1981 ◽  
Vol 33 (1) ◽  
pp. 102-104 ◽  
Author(s):  
Tsing-Chang Chen ◽  
Joseph J. Tribbia
Keyword(s):  
Kinetic Energy ◽  
Energy Spectra ◽  
Divergent Wind

scholarly journals Simulations of Nearshore Particle-Pair Dispersion in Southern California

2013 ◽  
Vol 43 (9) ◽  
pp. 1862-1879 ◽  
Author(s):  
Leonel Romero ◽  
Yusuke Uchiyama ◽  
J. Carter Ohlmann ◽  
James C. McWilliams ◽  
David A. Siegel
Keyword(s):  
Kinetic Energy ◽  
Southern California ◽  
Separation Distance ◽  
Horizontal Resolution ◽  
Particle Dispersion ◽  
Eddy Kinetic Energy ◽  
Relative Dispersion ◽  
Numerical Resolution ◽  
Relative Diffusivity ◽  
Pair Separation

Abstract Knowledge of horizontal relative dispersion in nearshore oceans is important for many applications including the transport and fate of pollutants and the dynamics of nearshore ecosystems. Two-particle dispersion statistics are calculated from millions of synthetic particle trajectories from high-resolution numerical simulations of the Southern California Bight. The model horizontal resolution of 250 m allows the investigation of the two-particle dispersion, with an initial pair separation of 500 m. The relative dispersion is characterized with respect to the coastal geometry, bathymetry, eddy kinetic energy, and the relative magnitudes of strain and vorticity. Dispersion is dominated by the submesoscale, not by tides. In general, headlands are more energetic and dispersive than bays. Relative diffusivity estimates are smaller and more anisotropic close to shore. Farther from shore, the relative diffusivity increases and becomes less anisotropic, approaching isotropy ~10 km from the coast. The degree of anisotropy of the relative diffusivity is qualitatively consistent with that for eddy kinetic energy. The total relative diffusivity as a function of pair separation distance R is on average proportional to R5/4. Additional Lagrangian experiments at higher horizontal numerical resolution confirmed the robustness of these results. Structures of large vorticity are preferably elongated and aligned with the coastline nearshore, which may limit cross-shelf dispersion. The results provide useful information for the design of subgrid-scale mixing parameterizations as well as quantifying the transport and dispersal of dissolved pollutants and biological propagules.

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