scholarly journals Characteristics of Atmospheric Kinetic Energy Spectra during the Intensification of Typhoon Lekima (2019)

2020 ◽  
Vol 10 (17) ◽  
pp. 6029 ◽  
Author(s):  
Hepeng Zheng ◽  
Yun Zhang ◽  
Yuan Wang ◽  
Lifeng Zhang ◽  
Jun Peng ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Spectral Shape ◽  
Energy Spectra ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Physical Processes ◽  
Rotational Mode ◽  
Atmospheric Energy

The intensification of Typhoon Lekima (2019) is simulated with the Weather Research and Forecasting model to study the atmospheric horizontal kinetic energy (HKE) spectra and corresponding spectral HKE budgets under the control of real tropical cyclone (TC). The results show that the TC has the ability to modify the canonical atmospheric energy spectrum during its evolution, which is dominated by its rotational mode. With the intensification of Lekima, the HKE spectrum in the troposphere swells over the central mesoscale and develops an arc-like shape. The stronger the TC, the more pronounced the arc-like shape is and the smaller scale it extends to. The roles various physical processes play at different heights and horizontal scales during the intensification of Lekima are investigated and the dependence of the effect of physical processes on scale and height is revealed. Meanwhile, the potential relationship between the intensification of TC, the activation of energy activity at smaller scales, and the downscale extension of the arc-like spectral shape is found.

scholarly journals Mesoscale Horizontal Kinetic Energy Spectra of a Tropical Cyclone

2018 ◽  
Vol 75 (10) ◽  
pp. 3579-3596 ◽  
Author(s):  
Yuan Wang ◽  
Lifeng Zhang ◽  
Jun Peng ◽  
Saisai Liu
Keyword(s):  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Gravity Waves ◽  
Lower Stratosphere ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Physical Processes ◽  
Upper Troposphere ◽  
Mature Period ◽  
Vertically Propagating

A high-resolution cloud-permitting simulation with the Weather Research and Forecasting (WRF) Model is performed to investigate the mesoscale horizontal kinetic energy (HKE) spectra of a tropical cyclone (TC). The spectrum displays an arc-like shape in the troposphere and a quasi-linear shape in the lower stratosphere for wavelengths below 500 km during the mature period of the TC, while they both develop a quasi −5/3 slope. The total HKE spectrum is dominated by its rotational component in the troposphere but by its divergent component in the lower stratosphere. Further spectral HKE budget diagnosis reveals a generally downscale cascade of HKE, although a local upscale cascade gradually forms in the lower stratosphere. However, the mesoscale energy spectrum is not only governed by the energy cascade, but is evidently influenced also by other physical processes, among which the buoyancy effect converts available potential energy (APE) to HKE in the mid- and upper troposphere and converts HKE to APE in the lower stratosphere, the vertically propagating inertia–gravity waves transport the HKE from the upper troposphere to lower and higher layers, and the vertical transportation of convection always transports HKE upward.

scholarly journals Measurement of ambient neutrons in an underground laboratory at the Kamioka Observatory

2018 ◽  
Vol 2018 (12) ◽  
Author(s):  
Keita Mizukoshi ◽  
Ryosuke Taishaku ◽  
Keishi Hosokawa ◽  
Kazuyoshi Kobayashi ◽  
Kentaro Miuchi ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Energy Spectrum ◽  
Neutron Flux ◽  
Thermal Neutron Flux ◽  
Spectral Shape ◽  
Underground Laboratory ◽  
Energy Spectra ◽  
Detector Response ◽  
Total Neutron ◽  
Important Input

Abstract Ambient neutrons are one of the most serious backgrounds for underground experiments searching for rare events. The ambient neutron flux in an underground laboratory at the Kamioka Observatory was measured using a $\mathrm{^3He}$ proportional counter with various moderator setups. Since the detector response largely depends on the spectral shape, the energy spectra of the neutrons transported from the rock to the laboratory were estimated by Monte Carlo simulations. The ratio of the thermal neutron flux to the total neutron flux was found to depend on the thermalizing efficiency of the rock. Therefore, the ratio of the count rate without a moderator to that with a moderator was used to determine this parameter. Consequently, the most likely neutron spectrum predicted by the simulations for the parameters determined by the experimental results was obtained. The result suggests an interesting spectral shape, which has not been indicated in previous studies. The total ambient neutron flux is $(23.5 \pm 0.7 \ \mathrm{_{stat.}} ^{+1.9}_{-2.1} \ \mathrm{_{sys.}}) \times 10^{-6}$ cm$^{-2}$ s$^{-1}$. This result, especially the energy spectrum information, could be a new and important input for estimating the background in current and future experiments in the underground laboratory at the Kamioka Observatory.

scholarly journals Regional Climate–Weather Research and Forecasting Model

2012 ◽  
Vol 93 (9) ◽  
pp. 1363-1387 ◽  
Author(s):  
Xin-Zhong Liang ◽  
Min Xu ◽  
Xing Yuan ◽  
Tiejun Ling ◽  
Hyun I. Choi ◽  
...  
Keyword(s):  
Weather Prediction ◽  
Regional Climate ◽  
Weather Forecast ◽  
Ecosystem Model ◽  
Climate Prediction ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Physical Processes ◽  
Terrestrial Hydrology ◽  
Weather Research

The CWRF is developed as a climate extension of the Weather Research and Forecasting model (WRF) by incorporating numerous improvements in the representation of physical processes and integration of external (top, surface, lateral) forcings that are crucial to climate scales, including interactions between land, atmosphere, and ocean; convection and microphysics; and cloud, aerosol, and radiation; and system consistency throughout all process modules. This extension inherits all WRF functionalities for numerical weather prediction while enhancing the capability for climate modeling. As such, CWRF can be applied seamlessly to weather forecast and climate prediction. The CWRF is built with a comprehensive ensemble of alternative parameterization schemes for each of the key physical processes, including surface (land, ocean), planetary boundary layer, cumulus (deep, shallow), microphysics, cloud, aerosol, and radiation, and their interactions. This facilitates the use of an optimized physics ensemble approach to improve weather or climate prediction along with a reliable uncertainty estimate. The CWRF also emphasizes the societal service capability to provide impactrelevant information by coupling with detailed models of terrestrial hydrology, coastal ocean, crop growth, air quality, and a recently expanded interactive water quality and ecosystem model. This study provides a general CWRF description and basic skill evaluation based on a continuous integration for the period 1979– 2009 as compared with that of WRF, using a 30-km grid spacing over a domain that includes the contiguous United States plus southern Canada and northern Mexico. In addition to advantages of greater application capability, CWRF improves performance in radiation and terrestrial hydrology over WRF and other regional models. Precipitation simulation, however, remains a challenge for all of the tested models.

scholarly journals Energy spectra in turbulent bubbly flows

2016 ◽  
Vol 791 ◽  
pp. 174-190 ◽  
Author(s):  
Vivek N. Prakash ◽  
J. Martínez Mercado ◽  
Leen van Wijngaarden ◽  
E. Mancilla ◽  
Y. Tagawa ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Kinetic Energy ◽  
Viscous Dissipation ◽  
Energy Production ◽  
Single Phase ◽  
Liquid Velocity ◽  
Bubbly Flow ◽  
Bubbly Flows ◽  
Energy Spectra ◽  
Physical Reason

We conduct experiments in a turbulent bubbly flow to study the nature of the transition between the classical $-5/3$ energy spectrum scaling for a single-phase turbulent flow and the $-3$ scaling for a swarm of bubbles rising in a quiescent liquid and of bubble-dominated turbulence. The bubblance parameter (Lance & Bataille J. Fluid Mech., vol. 222, 1991, pp. 95–118; Rensen et al., J. Fluid Mech., vol. 538, 2005, pp. 153–187), which measures the ratio of the bubble-induced kinetic energy to the kinetic energy induced by the turbulent liquid fluctuations before bubble injection, is often used to characterise bubbly flow. We vary the bubblance parameter from $b=\infty$ (pseudoturbulence) to $b=0$ (single-phase flow) over 2–3 orders of magnitude (0.01–5) to study its effect on the turbulent energy spectrum and fluctuations in liquid velocity. The probability density functions (PDFs) of the fluctuations in liquid velocity show deviations from the Gaussian profile for $b>0$, i.e. when bubbles are present in the system. The PDFs are asymmetric with higher probability in the positive tails. The energy spectra are found to follow the $-3$ scaling at length scales smaller than the size of the bubbles for bubbly flows. This $-3$ spectrum scaling holds not only in the well-established case of pseudoturbulence, but surprisingly in all cases where bubbles are present in the system ($b>0$). Therefore, it is a generic feature of turbulent bubbly flows, and the bubblance parameter is probably not a suitable parameter to characterise the energy spectrum in bubbly turbulent flows. The physical reason is that the energy input by the bubbles passes over only to higher wavenumbers, and the energy production due to the bubbles can be directly balanced by the viscous dissipation in the bubble wakes as suggested by Lance & Bataille (1991). In addition, we provide an alternative explanation by balancing the energy production of the bubbles with viscous dissipation in the Fourier space.

scholarly journals Accuracy of Rotational and Divergent Kinetic Energy Spectra Diagnosed from Flight-Track Winds

2016 ◽  
Vol 73 (8) ◽  
pp. 3273-3286 ◽  
Author(s):  
Lotte Bierdel ◽  
Chris Snyder ◽  
Sang-Hun Park ◽  
William C. Skamarock
Keyword(s):  
Water Vapor ◽  
Kinetic Energy ◽  
Energy Spectra ◽  
Commercial Aircraft ◽  
Rotational Mode ◽  
One Dimensional ◽  
Significant Dependence ◽  
Rotational Components ◽  
Atmospheric Simulations

Abstract Under assumptions of horizontal homogeneity and isotropy, one may derive relations between rotational or divergent kinetic energy spectra and velocities along one-dimensional tracks, such as might be measured by aircraft. Two recent studies, differing in details of their implementation, have applied these relations to the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) dataset and reached different conclusions with regard to the mesoscale ratio of divergent to rotational kinetic energy. In this study the accuracy of the method is assessed using global atmospheric simulations performed with the Model for Prediction Across Scales, where the exact decomposition of the horizontal winds into divergent and rotational components may be easily computed. For data from the global simulations, the two approaches yield similar and very accurate results. Errors are largest for the divergent component on synoptic scales, which is shown to be related to a very dominant rotational mode. The errors are, in particular, sufficiently small so that the mesoscale ratio of divergent to rotational kinetic energy can be derived correctly. The proposed technique thus provides a strong observational check of model results with existing large commercial aircraft datasets. The results do, however, show a significant dependence on the height and latitude ranges considered, and the disparate conclusions drawn from previous applications to MOZAIC data may result from the use of different subsets of the data.

scholarly journals The Influences of Boundary Layer Mixing and Cloud-Radiative Forcing on Tropical Cyclone Size

2017 ◽  
Vol 74 (4) ◽  
pp. 1273-1292 ◽  
Author(s):  
Yizhe Peggy Bu ◽  
Robert G. Fovell ◽  
Kristen L. Corbosiero
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Radiative Forcing ◽  
Vertical Mixing ◽  
Outer Core ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Convective Activity ◽  
Cloud Radiative Forcing ◽  
Mixing Coefficient

Abstract Tropical cyclone (TC) size is an important factor directly and indirectly influencing track, intensity, and related hazards, such as storm surge. Using a semi-idealized version of the operational Hurricane Weather Research and Forecasting Model (HWRF), the authors show that both enabling cloud-radiative forcing (CRF) and enhancing planetary boundary layer (PBL) vertical mixing can encourage wider storms by enhancing TC outer-core convective activity. While CRF acts primarily above the PBL, eddy mixing moistens the boundary layer from below, both making peripheral convection more likely. Thus, these two processes can cooperate and compete, making their influences difficult to deconvolve and complicating the evaluation of model physics improvements, especially since the sensitivity to both decreases as the environment becomes less favorable. Further study shows not only the magnitude of the eddy mixing coefficient but also the shape of it can determine the TC size and structure.

scholarly journals The energy spectrum in a barotropic atmosphere

2008 ◽  
Vol 15 ◽  
pp. 17-22 ◽  
Author(s):  
M. V. Kurgansky
Keyword(s):  
Energy Spectrum ◽  
Kinetic Energy ◽  
Discrete Spectrum ◽  
Energy Spectra ◽  
Two Dimensional ◽  
Barotropic Model ◽  
Atmospheric Sciences ◽  
Rotating Sphere ◽  
Barotropic Atmosphere ◽  
Mathematical Techniques

Abstract. In a forced-dissipative barotropic model of the atmosphere on a spherical planet, by following mathematical techniques in (Thompson, P. D.: The equilibrium energy spectrum of randomly forced two-dimensional turbulence, Journal of the Atmospheric Sciences, 30, 1593–1598, 1973) but applying them in a novel context of the discrete spectrum on a rotating sphere, the "minus 2" energy spectrum for wavenumbers much greater than a characteristic wavenumber of the baroclinic forcing has been obtained if the forcing is taken in the simplest and most fundamental form. Some observation-based atmospheric kinetic energy spectra, with their slopes lying between "minus 2" and "minus 3" laws, are discussed from the perspective of the deduced "minus 2" energy spectrum.

Application of a new scale-aware three-dimensional subgrid mixing parameterization on the simulations of tropical cyclone

2020 ◽  
Author(s):  
mengjuan liu ◽  
Xu Zhang
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Turbulent Mixing ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Gray Zone ◽  
Synoptic Observations ◽  
Mobile Boundary

<p>A new scale-adaptive three-dimensional (3D) turbulent kinetic energy (TKE) subgrid mixing scheme is developed using the Advanced Research version of the Weather Research and Forecasting Model (WRF-ARW) to address the gray-zone problem in the parameterization of subgrid turbulent mixing. This scheme is based on the full 3D TKE prognostic equation and combines the horizontal and vertical subgrid turbulent mixing into a single energetically consistent framework.</p><p>A series of real tropical cyclone(TC) simulations with varying horizontal resolutions from 9km to 1km are carried out to compare the performance of the 3D mixing scheme and the conventional 1D planetary boundary layer (PBL) schemes to the observations, including conventional ones such as radiosonde and surface synoptic observations, as well as intensive ones obtained during the landfall of TC, such as mobile boundary layer wind profiler and Dual-pol Doppler Radar. This study aims to determine if the new scheme performs appropriate on TC simulation, and to evaluate the sensitivity of TC simulation to boundary layer schemes.</p>

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