scholarly journals Tropical Cyclone Tornadoes, 1950–2007

2009 ◽  
Vol 137 (10) ◽  
pp. 3471-3484 ◽  
Author(s):  
Lori A. Schultz ◽  
Daniel J. Cecil
Keyword(s):  
At Risk ◽  
Tropical Cyclone ◽  
Outer Region ◽  
Time Of Day ◽  
Core Region ◽  
Strong Preference ◽  
General Terms ◽  
Inner Region

Abstract An expanded “climatology” of U.S. tropical cyclone (TC) tornadoes covering the period 1950–2007 is presented. A major climatology published in 1991 included data on 626 TC tornadoes. Since then, almost 1200 more TC tornado records have been identified, with almost half of that number from the 2004–05 seasons alone. This work reexamines some findings from previous studies, using a substantially larger database. The new analyses strongly support distinctions between inner- and outer-region tornadoes, which were suggested in previous studies. Outer-region tornadoes (beyond 200 km from the TC center) have a stronger diurnal signal, commonly occurring during the afternoon. Inner-region tornadoes typically occur within ∼12 h of TC landfall, with no strong preference for a particular time of day. They are disproportionately less damaging tornadoes, with more rated F0 than in the outer-region sample. In more general terms, the TC tornado database includes a smaller percentage of significant (≥F2) tornadoes (14%) than does the overall U.S. tornado database (22%). Most TC tornadoes (60%) occur within 100 km of the coast; this includes core-region tornadoes near the time of landfall as well as tornadoes from rainbands coming ashore far from the circulation center. The F0-rated tornadoes are slightly more common near the coast but compose a smaller percentage of the tornadoes inland. The threat often persists for 2–3 days after landfall and extends ∼400 km inland and ∼500 km from the TC center, although there is much case-to-case variability. This puts locations at risk that might otherwise avoid damage from the TC.

Vertical Structure of Tropical Cyclone Rainbands as Seen by the TRMM Precipitation Radar

2012 ◽  
Vol 69 (9) ◽  
pp. 2644-2661 ◽  
Author(s):  
Deanna A. Hence ◽  
Robert A. Houze
Keyword(s):  
Tropical Cyclone ◽  
Wind Shear ◽  
Vertical Structure ◽  
Outer Region ◽  
Asymmetric Distribution ◽  
Precipitation Radar ◽  
Radar Echo ◽  
The Right ◽  
Convective Cells ◽  
Inner Region

Abstract Ten years of data from the Tropical Rainfall Measurement Mission satellite’s Precipitation Radar (TRMM PR) show the vertical structure of tropical cyclone rainbands. Radar-echo statistics show that rainbands have a two-layered structure, with distinct modes separated by the melting layer. The ice layer is a combination of particles imported from the eyewall and ice left aloft as convective cells collapse. This layering is most pronounced in the inner region of the storm, and the layering is enhanced by storm strength. The inner-region rainbands are vertically confined by outflow from the eyewall but nevertheless are a combination of strong embedded convective cells and robust stratiform precipitation, both of which become more pronounced in stronger cyclones. Changes in rainband coverage, vertical structure, and the amount of active convection indicate a change in the nature of rainbands between the regions inward and outward of a radius of approximately 200 km. Beyond this radius, rainbands consist of more sparsely distributed precipitation that is more convective in nature than that of the inner-region rainbands, and the outer-region rainband structures are relatively insensitive to changes in storm intensity. The rainbands in both inner and outer regions are organized with respect to the environmental wind shear vector. The right-of-shear quadrants contain newer convection while in the left-of-shear quadrants the radar echoes are predominantly stratiform. This asymmetric distribution of rainband structures strengthens with environmental wind shear. Cool sea surfaces discourage rainband convection uniformly.

scholarly journals Revisiting the Balanced and Unbalanced Aspects of Tropical Cyclone Intensification

2017 ◽  
Vol 74 (8) ◽  
pp. 2575-2591 ◽  
Author(s):  
Junyao Heng ◽  
Yuqing Wang ◽  
Weican Zhou
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Inner Core ◽  
Model Simulation ◽  
Surface Friction ◽  
Core Region ◽  
Physics Model ◽  
The One ◽  
Balanced Dynamics ◽  
Balanced Solution

Abstract The balanced and unbalanced aspects of tropical cyclone (TC) intensification are revisited with the balanced contribution diagnosed with the outputs from a full-physics model simulation of a TC using the Sawyer–Eliassen (SE) equation. The results show that the balanced dynamics can well capture the secondary circulation in the full-physics model simulation even in the inner-core region in the boundary layer. The balanced dynamics can largely explain the intensification of the simulated TC. The unbalanced dynamics mainly acts to prevent the boundary layer agradient flow in the inner-core region from further intensification. Although surface friction can enhance the boundary layer inflow and make the inflow penetrate more inward into the eye region, contributing to the eyewall contraction, the net dynamical effect of surface friction on TC intensification is negative. The sensitivity of the balanced solution to the procedure used to ensure the ellipticity condition for the SE equation is also examined. The results show that the boundary layer inflow in the balanced response is very sensitive to the adjustment to inertial stability in the upper troposphere and the calculation of radial wind at the surface with relatively coarse vertical resolution in the balanced solution. Both the use of the so-called global regularization and the one-sided finite-differencing scheme used to calculate the surface radial wind in the balanced solution as utilized in some previous studies can significantly underestimate the boundary layer inflow. This explains why the boundary layer inflow in the balanced response is too weak in some previous studies.

Measurement and Analysis of Buoyancy-Induced Heat Transfer in Aero-Engine Compressor Rotors

2020 ◽  
Author(s):  
Richard W. Jackson ◽  
Dario Luberti ◽  
Hui Tang ◽  
Oliver J. Pountney ◽  
James A. Scobie ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Outer Region ◽  
Conjugate Problem ◽  
Radial Temperature ◽  
Nusselt Numbers ◽  
Induced Flow ◽  
Aero Engines ◽  
Inner Region ◽  
Buoyancy Induced Flow

Abstract The flow inside cavities between co-rotating compressor discs of aero-engines is driven by buoyancy, with Grashof numbers exceeding 1013. This phenomenon creates a conjugate problem: the Nusselt numbers depend on the radial temperature distribution of the discs, and the disc temperatures depend on the Nusselt numbers. Furthermore, Coriolis forces in the rotating fluid generate cyclonic and anti-cyclonic circulations inside the cavity. Such flows are three-dimensional, unsteady and unstable, and it is a challenge to compute and measure the heat transfer from the discs to the axial throughflow in the compressor. In this paper, Nusselt numbers are experimentally determined from measurements of steady-state temperatures on the surfaces of both discs in a rotating cavity of the Bath Compressor-Cavity Rig. The data are collected over a range of engine-representative parameters and are the first results from a new experimental facility specifically designed to investigate buoyancy-induced flow. The radial distributions of disc temperature were collected under carefully-controlled thermal boundary conditions appropriate for analysis using a Bayesian model combined with the equations for a circular fin. The Owen-Tang buoyancy model has been used to compare predicted radial distributions of disc temperatures and Nusselt numbers with some of the experimentally determined values, taking account of radiation between the interior surfaces of the cavity. The experiments show that the average Nusselt numbers on the disc increase as the buoyancy forces increase. At high rotational speeds the temperature rise in the core, created by compressibility effects in the air, attenuates the heat transfer and there is a critical rotational Reynolds number for which the Nusselt number is a maximum. In the cavity, there is an inner region dominated by forced convection and an outer region dominated by buoyancy-induced flow. The inner region is a mixing region, in which entrained cold throughflow encounters hot flow from the Ekman layers on the discs. Consequently, the Nusselt numbers on the downstream disc in the inner region tend to be higher than those on the upstream disc.

Small Péclet-number mass transport to a finite strip: An advection–diffusion–reaction model of surface-based biosensors

2019 ◽  
Vol 31 (5) ◽  
pp. 763-781
Author(s):  
EHUD YARIV
Keyword(s):  
Shear Flow ◽  
Mass Transport ◽  
Sherwood Number ◽  
Peclet Number ◽  
Outer Region ◽  
Diffusion Reaction ◽  
Background Concentration ◽  
Leading Order ◽  
Péclet Number ◽  
Inner Region

AbstractWe consider two-dimensional mass transport to a finite absorbing strip in a uniform shear flow as a model of surface-based biosensors. The quantity of interest is the Sherwood number Sh, namely the dimensionless net flux onto the strip. Considering early-time absorption, it is a function of the Péclet number Pe and the Damköhler number Da, which, respectively, represent the characteristic magnitude of advection and reaction relative to diffusion. With a view towards modelling nanoscale biosensors, we consider the limit Pe«1. This singular limit is handled using matched asymptotic expansions, with an inner region on the scale of the strip, where mass transport is diffusively dominated, and an outer region at distances that scale as Pe-1/2, where advection enters the dominant balance. At the inner region, the mass concentration possesses a point-sink behaviour at large distances, proportional to Sh. A rescaled concentration, normalised using that number, thus possesses a universal logarithmic divergence; its leading-order correction represents a uniform background concentration. At the outer region, where advection by the shear flow enters the leading-order balance, the strip appears as a point singularity. Asymptotic matching with the concentration field in that region provides the Sherwood number as $${\rm{Sh}} = {\pi \over {\ln (2/{\rm{P}}{{\rm{e}}^{1/2}}) + 1.0559 + \beta }},$$ wherein β is the background concentration. The latter is determined by the solution of the canonical problem governing the rescaled inner concentration, and is accordingly a function of Da alone. Using elliptic-cylinder coordinates, we have obtained an exact solution of the canonical problem, valid for arbitrary values of Da. It is supplemented by approximate solutions for both small and large Da values, representing the respective limits of reaction- and transport-limited conditions.

scholarly journals Photophoresis in the circumjovian disk and its impact on the orbital configuration of the Galilean satellites

2019 ◽  
Vol 629 ◽  
pp. A106 ◽  
Author(s):  
Sota Arakawa ◽  
Yuhito Shibaike
Keyword(s):  
Density Distribution ◽  
Accretion Disks ◽  
Surface Density ◽  
Outer Region ◽  
Dust Particles ◽  
Magnetorotational Instability ◽  
Galilean Satellites ◽  
Ionization Fraction ◽  
Orbital Configuration ◽  
Inner Region

Jupiter has four large regular satellites called the Galilean satellites: Io, Europa, Ganymede, and Callisto. The inner three of the Galilean satellites orbit in a 4:2:1 mean motion resonance; therefore their orbital configuration may originate from the stopping of the migration of Io near the bump in the surface density distribution and following resonant trapping of Europa and Ganymede. The formation mechanism of the bump near the orbit of the innermost satellite, Io, is not yet understood, however. Here, we show that photophoresis in the circumjovian disk could be the cause of the bump using analytic calculations of steady-state accretion disks. We propose that photophoresis in the circumjovian disk could stop the inward migration of dust particles near the orbit of Io. The resulting dust-depleted inner region would have a higher ionization fraction, and thus admit increased magnetorotational-instability-driven accretion stress in comparison to the outer region. The increase of the accretion stress at the photophoretic dust barrier would form a bump in the surface density distribution, halting the migration of Io.

Investigation on the Radial Heat-Transfer of Pumping Secondary Flow in Semiclosed Rotating Disk Cavity

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Guohu Luo ◽  
Zhenqiang Yao
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Outer Region ◽  
Rotating Disk ◽  
Mean Flow ◽  
Coolant Pump ◽  
Radial Temperature ◽  
Type Flow ◽  
Radial Heat ◽  
Inner Region

Abstract This study investigates the mean flow and radial heat-transfer behaviors in semiclosed rotating disk cavity within the canned reactor coolant pump. The flow in the semiclosed cavity contains the Stewartson type flow at inner region and the Batchelor type flow at outer region. The heat is radially transported from the outer rim of the semiclosed disk cavity to discharge-hole through the nondirect discharge (ND) portion of the superimposed flow from inlet. The effects of rotating Reynolds numbers, cavity aspect ratio and radial location of discharge-hole on the discharge ratio, pumping mass flow rate, local wall shear stress and radial heat-transfer coefficient are examined in the semiclosed rotating cavity flow, respectively. Based on the radial heat transfer behaviors of pumping secondary flow, an equivalent thermal network is proposed and validated by experiments, which can effectively predict the radial temperature distribution from the discharge hole to periphery with the viscous-heating and nonisothermal effects.

scholarly journals 11.16. On the origin of density cusp in galactic nuclei by central black hole

1998 ◽  
Vol 184 ◽  
pp. 487-488
Author(s):  
T. Nakano ◽  
T. Fukushige ◽  
J. Makino
Keyword(s):  
Black Hole ◽  
Hubble Space Telescope ◽  
Outer Region ◽  
Elliptical Galaxies ◽  
Heating Process ◽  
Massive Black Hole ◽  
Weak Density ◽  
The Galaxy ◽  
Galaxy Model ◽  
Inner Region

We investigated the dynamical reaction of the central region of galaxies to a falling massive black hole by N-body simulations. As the initial galaxy model, we used an isothermal King model and placed a massive black hole at around the half-mass radius of the galaxy. We found that the central core of the galaxy is destroyed by the heating due to the black hole and a very weak density cusp (ρ ∝ r−α, with α ∼ 0.5) is formed around the center. This result is consistent with recent observations of large elliptical galaxies by Hubble Space Telescope (Lauer et al. 1995; Byun et al. 1996; Gebhardt et al. 1996; Faber et al. 1996; Kormendy et al. 1996). The radius of the weak cusp region is large for large black hole mass. The velocity of the stars become tangentially anisotropic in the inner region, while in the outer region the stars have radially anisotropic velocity dispersion. Our result naturally explains the mechanism of the formation of the weak cusp found in the previous simulations of galaxy merging, and implies that the weak cusp observed in large elliptical galaxies may be formed by the heating process by sinking black holes during merging events.

scholarly journals Vortex Spinup Process in the Extratropical Transition of Hurricane Sandy (2012)

2019 ◽  
Vol 76 (11) ◽  
pp. 3589-3610 ◽  
Author(s):  
Jung Hoon Shin
Keyword(s):  
Structural Changes ◽  
Outer Region ◽  
Momentum Equation ◽  
Hurricane Sandy ◽  
Core Region ◽  
Local Wind ◽  
Extratropical Transition ◽  
The Core ◽  
Tangential Wind ◽  
Baroclinic Zone

Abstract This study utilizes the quasi-Lagrangian azimuthal momentum equation (i.e., budget calculation) and 1.667-km-resolution numerical simulation data to study the intensity and structural changes in Hurricane Sandy’s extratropical transition. The results indicate that after the onset of extratropical transition, Sandy maintains an eyewall-like convection and warm core in the core region and has a frontal structure in the outer region. In the outer region, baroclinicity-driven frontal convection induces extensive planetary boundary layer (PBL) inflow, causing an inward advection of absolute angular momentum (AAM) per unit radius, which generates outer local wind maxima and expands Sandy’s outer wind field through a spinup process. Moreover, because the outer tangential wind velocity accelerates in a frontal convection, local wind maxima associated with fronts can expand to the outer sides of frontal regions. Frontal convection increases AAM in the outer region, providing the precondition for reintensification; however, the front itself cannot cause Sandy’s reintensification. The eyewall-like convection in the core region still plays an important role in Sandy’s reintensification. When the baroclinic zone, where a strong horizontal temperature gradient exists, approaches the core region, the eyewall-like convection is enhanced because the warm, moist air of the core region is lifted by the cold, dry air associated with the approaching baroclinic zone. Consequently, owing to the enhancement of eyewall-like convection, the PBL inflow, which extends from the outer region to the core region, develops. This inflow increases the inward transportation of the outer frontal region’s high-AAM air, thus leading to spinning up the core region’s wind and reintensification.

scholarly journals Changes in Morphological and Physicochemical Properties of Waxy and Non-waxy Proso Millets during Cooking Process

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 583 ◽  
Author(s):  
Qinghua Yang ◽  
Long Liu ◽  
Weili Zhang ◽  
Jing Li ◽  
Xiaoli Gao ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Cross Sections ◽  
Nutritional Value ◽  
Outer Region ◽  
Pasting Properties ◽  
Cooking Time ◽  
Ordered Structures ◽  
Proso Millet ◽  
Cooking Process ◽  
Inner Region

Proso millet, a grain which is principally consumed in cooked form, is favored by consumers because of its rich nutritional value. However, the changes in morphological and physicochemical properties of proso millet grains occurring during the cooking process have rarely been reported. In this study, we investigated the changes in morphological and physicochemical properties of cooked waxy and non-waxy proso millets. During the cooking process, starch granules in the grains were gradually gelatinized starting from the outer region to the inner region and were gelatinized earlier in waxy proso millet than in non-waxy proso millet. Many filamentous network structures were observed in the cross sections of cooked waxy proso millet. As the cooking time increased, the long- and short-range, ordered structures of proso millets were gradually disrupted, and the ordered structures were fully disrupted by 20 min of cooking. In both waxy and non-waxy proso millets, thermal and pasting properties significantly changed with an increase in the cooking time. This study provides useful information for the processing of proso millet in the food industry.

scholarly journals A new model for dark matter fluid sphere

2020 ◽  
Vol 35 (34) ◽  
pp. 2050280
Author(s):  
Shyam Das ◽  
Nayan Sarkar ◽  
Monimala Mondal ◽  
Farook Rahaman
Keyword(s):  
Dark Matter ◽  
Compact Star ◽  
Outer Region ◽  
Fluid Sphere ◽  
Constant Density ◽  
Spherically Symmetric ◽  
Causality Condition ◽  
New Model ◽  
Inner Region ◽  
Tov Equation

We develop a new model for a spherically symmetric dark matter fluid sphere containing two regions: (i) Isotropic inner region with constant density and (ii) Anisotropic outer region. We solve the system of field equation by assuming a particular density profile along with a linear equation of state. The obtained solutions are well-behaved and physically acceptable which represent equilibrium and stable matter configuration by satisfying the Tolman–Oppenheimer–Volkoff (TOV) equation and causality condition, condition on adiabatic index, Harrison–Zeldovich–Novikov criterion, respectively. We consider the compact star EXO 1785-248 (Mass [Formula: see text] and radius R[Formula: see text]8.8 km) to analyze our solutions by graphical demonstrations.

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