scholarly journals Diurnal Cycle of Rainfall Associated with Landfalling Tropical Cyclones in China from Rain Gauge Observations

2017 ◽  
Vol 56 (9) ◽  
pp. 2595-2605 ◽  
Author(s):  
Hao Hu ◽  
Yihong Duan ◽  
Yuqing Wang ◽  
Xinghai Zhang
Keyword(s):  
Tropical Cyclones ◽  
Diurnal Cycle ◽  
Rain Rate ◽  
Inner Core ◽  
Outer Region ◽  
Rain Gauge ◽  
Core Region ◽  
The Core ◽  
Storm Center ◽  
Landfalling Tropical Cyclones

AbstractThe diurnal variation of rainfall over China associated with landfalling tropical cyclones (TCs) is investigated using hourly rain gauge observations obtained from 2425 conventional meteorological stations in China. Records between 12 h prior to landfall and 12 h after landfall of 450 landfalling TCs in China from 1957 to 2014 are selected as samples. The harmonic analysis shows an obvious diurnal signal in TC rainfall with a rain-rate peak in the early morning and a minimum in the afternoon. The diurnal cycle in the outer region (between 400- and 900-km radii from the storm center) is found to be larger than in the core region (within 400 km of the storm center). This could be attributed to the effect of land on the inner core of the storms as the diurnal cycle is distinct in the core region well before landfall. As the result of this diurnal cycle, TCs making landfall at night tend to have cumulative precipitation, defined as the precipitation cumulated from the time at landfall to 12 h after landfall, about 30% larger than those making landfall around noon or afternoon. Moreover, the radial propagation of the diurnal cycle in TC rain rate, which has been a controversial phenomenon in some previous studies with remote sensing observations, was not present in this study that is based on rain gauge observations. Results also show that the diurnal signal has little dependence on the storm intensity 12 h prior to landfall.

scholarly journals Recent global decrease in the inner-core rain rate of tropical cyclones

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shifei Tu ◽  
Jianjun Xu ◽  
Johnny C. L. Chan ◽  
Kian Huang ◽  
Feng Xu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Numerical Model ◽  
Surface Temperature ◽  
Tropical Cyclones ◽  
Heavy Rainfall ◽  
Rain Rate ◽  
Inner Core ◽  
Atmospheric Stability ◽  
Outer Region ◽  
The Other

AbstractHeavy rainfall is one of the major aspects of tropical cyclones (TC) and can cause substantial damages. Here, we show, based on satellite observational rainfall data and numerical model results, that between 1999 and 2018, the rain rate in the outer region of TCs has been increasing, but it has decreased significantly in the inner-core. Globally, the TC rain rate has increased by 8 ± 4% during this period, which is mainly contributed by an increase in rain rate in the TC outer region due to increasing water vapor availability in the atmosphere with rising surface temperature. On the other hand, the rain rate in the inner-core of TCs has decreased by 24 ± 3% during the same period. The decreasing trend in the inner-core rain rate likely results mainly from an increase in atmospheric stability.

Do Gravity Waves Transport Angular Momentum away from Tropical Cyclones?

2010 ◽  
Vol 67 (1) ◽  
pp. 117-135 ◽  
Author(s):  
Yumin Moon ◽  
David S. Nolan
Keyword(s):  
Angular Momentum ◽  
Tropical Cyclones ◽  
Gravity Waves ◽  
Inner Core ◽  
Three Dimensional ◽  
Core Region ◽  
Heat Sources ◽  
Angular Momentum Transport ◽  
The Core ◽  
Anelastic Equations

Abstract Previous studies have suggested that gravity waves can transport a significantly large amount of angular momentum away from tropical cyclones, as much as 10% of the core angular momentum per hour. These previous studies used the shallow-water equations to model gravity waves radiating outward from rapidly rotating inner-core asymmetries. This issue is reinvestigated with a three-dimensional, nonhydrostatic, linear model of the vortex-anelastic equations. The response of balanced, axisymmetric vortices modeled after tropical cyclones to rotating asymmetric heat sources is examined to assess angular momentum transport by gravity waves radiating away from the core region of the vortices. Calculations show that gravity waves do transport angular momentum away from the vortex core; however, the amount transported is several orders of magnitude smaller than recent estimates.

scholarly journals Structural Analysis of the Core Region of O-Lipopolysaccharide of Porphyromonas gingivalis from Mutants Defective in O-Antigen Ligase and O-Antigen Polymerase

2009 ◽  
Vol 191 (16) ◽  
pp. 5272-5282 ◽  
Author(s):  
Nikolay A. Paramonov ◽  
Joseph Aduse-Opoku ◽  
Ahmed Hashim ◽  
Minnie Rangarajan ◽  
Michael A. Curtis
Keyword(s):  
Porphyromonas Gingivalis ◽  
Inner Core ◽  
Outer Region ◽  
Outer Core ◽  
Core Region ◽  
Resonance Spectroscopy ◽  
Core Oligosaccharide ◽  
Unusual Structure ◽  
The Core ◽  
O Antigen

ABSTRACT Porphyromonas gingivalis synthesizes two lipopolysaccharides (LPSs), O-LPS and A-LPS. Here, we elucidate the structure of the core oligosaccharide (OS) of O-LPS from two mutants of P. gingivalis W50, ΔPG1051 (WaaL, O-antigen ligase) and ΔPG1142 (O-antigen polymerase), which synthesize R-type LPS (core devoid of O antigen) and SR-type LPS (core plus one repeating unit of O antigen), respectively. Structural analyses were performed using one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy in combination with composition and methylation analysis. The outer core OS of O-LPS occurs in two glycoforms: an “uncapped core,” which is devoid of O polysaccharide (O-PS), and a “capped core,” which contains the site of O-PS attachment. The inner core region lacks l(d)-glycero-d(l)-manno-heptosyl residues and is linked to the outer core via 3-deoxy-d-manno-octulosonic acid, which is attached to a glycerol residue in the outer core via a monophosphodiester bridge. The outer region of the “uncapped core” is attached to the glycerol and is composed of a linear α-(1→3)-linked d-Man OS containing four or five mannopyranosyl residues, one-half of which are modified by phosphoethanolamine at position 6. An amino sugar, α-d-allosamine, is attached to the glycerol at position 3. In the “capped core,” there is a three- to five-residue extension of α-(1→3)-linked Man residues glycosylating the outer core at the nonreducing terminal residue. β-d-GalNAc from the O-PS repeating unit is attached to the nonreducing terminal Man at position 3. The core OS of P. gingivalis O-LPS is therefore a highly unusual structure, and it is the basis for further investigation of the mechanism of assembly of the outer membrane of this important periodontal bacterium.

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 A Numerical Investigation of Wet and Dry Onset Modes in the North American Monsoon Core Region. Part I: A Regional Mechanism for Interannual Variability

2012 ◽  
Vol 25 (11) ◽  
pp. 3953-3969 ◽  
Author(s):  
Cuauhtémoc Turrent ◽  
Tereza Cavazos
Keyword(s):  
Interannual Variability ◽  
Diurnal Cycle ◽  
North American ◽  
Gulf Of California ◽  
Deep Convection ◽  
Core Region ◽  
Eastern Pacific ◽  
North American Monsoon ◽  
The Core ◽  
The North

In this study the results of two regional fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) simulations forced at their boundaries with low-pass-filtered North American Regional Reanalysis (NARR) composite fields from which synoptic-scale variability was removed are presented. The filtered NARR data are also assimilated into the inner domain through the use of field nudging. The purpose of this research is to investigate wet and dry onset modes in the core region of the North American monsoon (NAM). Key features of the NAM that are present in the NARR fields and assimilated into the regional simulations include the position of the midlevel anticyclone, low-level circulation over the Gulf of California, and moisture flux patterns into the core monsoon region, for which the eastern Pacific is the likely primary source of moisture. The model develops a robust diurnal cycle of deep convection over the peaks of the Sierra Madre Occidental (SMO) that results solely from its radiation scheme and internal dynamics, in spite of the field nudging. The wet onset mode is related to a regional land–sea thermal contrast (LSTC) that is ~2°C higher than in the dry mode, and is further characterized by a northward-displaced midlevel anticyclone, a stronger surface pressure gradient along the Gulf of California, larger mean moisture fluxes into the core region from the eastern Pacific, a stronger diurnal cycle of deep convection, and the more northward distribution of precipitation along the axis of the SMO. A proposed regional LSTC mechanism for NAM onset interannual variability is consistent with the differences between both onset modes.

scholarly journals A Numerical Study of Cirrus Bands and Low Static-stability Layers associated with Tropical Cyclone Outflow

2021 ◽  
Author(s):  
Masayuki Kawashima
Keyword(s):  
Numerical Study ◽  
Potential Temperature ◽  
Outer Region ◽  
Static Stability ◽  
Core Region ◽  
Thin Layers ◽  
Vertical Shear ◽  
Thermal Gradients ◽  
Shallow Convection ◽  
The Core

AbstractProminent cirrus cloud banding occurred episodically within a northern cirrus canopy of Typhoon Talim (2017) during its recurvature. The generation mechanisms of the cirrus bands and low static-stability layers that support the bands are investigated using a numerical simulation with the Advanced Research Weather Research and Forecasting Model. Inspection of model output reveals that thin layers of near-neutral to weakly unstable static stability are persistently present in the upper and lower parts of the upper-level outflow, and shallow convection aligned along the vertical shear vector is prevalent in these layers. The cirrus banding occurs as the lowered outflow from the weakening storm ascends slantwise over a midlatitude baroclinic zone, and updrafts of the preexisting shallow convection in the upper part of the outflow layer become saturated. It is shown that the strong outflow resulting from violation of gradient-wind balance in the core region, by itself, creates the low static-stability layers. Analyses of potential temperature and static stability budgets show that the low static-stability layers are created mainly by the differential radial advection of radial thermal gradients on the vertical edges of the outflow. The radial thermal gradients occur in response to the outward air parcel acceleration in the core region and deceleration in the outer region, which, by inducing compensating vertical mass transport into and out of the outflow, act to tilt the isentropes within the shear layers. The effects of environmental flow and cloud radiative forcing on the cirrus banding are also addressed.

scholarly journals Horizontal Transition of Turbulent Cascade in the Near-Surface Layer of Tropical Cyclones

2015 ◽  
Vol 72 (12) ◽  
pp. 4915-4925 ◽  
Author(s):  
Jie Tang ◽  
David Byrne ◽  
Jun A. Zhang ◽  
Yuan Wang ◽  
Xiao-tu Lei ◽  
...  
Keyword(s):  
Surface Layer ◽  
Tropical Cyclones ◽  
Inner Core ◽  
Outer Core ◽  
Core Region ◽  
Near Surface ◽  
Sources And Sinks ◽  
Available Energy ◽  
Energy Transportation ◽  
Turbulent Cascade

Abstract Tropical cyclones (TC) consist of a large range of interacting scales from hundreds of kilometers to a few meters. The energy transportation among these different scales—that is, from smaller to larger scales (upscale) or vice versa (downscale)—may have profound impacts on TC energy dynamics as a result of the associated changes in available energy sources and sinks. From multilayer tower measurements in the low-level (<120 m) boundary layer of several landing TCs, the authors found there are two distinct regions where the energy flux changes from upscale to downscale as a function of distance to the storm center. The boundary between these two regions is approximately 1.5 times the radius of maximum wind. Two-dimensional turbulence (upscale cascade) occurs more typically at regions close to the inner-core region of TCs, while 3D turbulence (downscale cascade) mostly occurs at the outer-core region in the surface layer.

Valence and core region energies of atoms in Hartree–Fock theory

1992 ◽  
Vol 70 (2) ◽  
pp. 537-546 ◽  
Author(s):  
S. Fliszár ◽  
N. Desmarais ◽  
G. Dancausse
Keyword(s):  
Inner Core ◽  
Core Region ◽  
Hartree Fock ◽  
The Core ◽  
Valence Region ◽  
Valence Electrons ◽  
Core Electrons ◽  
Discrete Values ◽  
Definition Of ◽  
Hf Wave

The subdivision of an atom into an inner core and an outer valence region reveals an interesting statistical aspect about the Hartree–Fock (HF) eigenvalues, εi, and the electron populations in the valence region, [Formula: see text] namely [Formula: see text] where Tv and [Formula: see text] are, respectively, the kinetic energy and the nuclear-electronic potential energy of the [Formula: see text] valence electrons, [Formula: see text] the interelectronic repulsion confined within the valence region, while [Formula: see text] is the repulsion between the core electrons and those of the valence region. This relationship (and a similar one for the core region) holds for any number of electrons arbitrarily assigned to the core, but is accurate only for HF (or near-HF) wave functions. This leads to a definition of the valence region energy, [Formula: see text] which, however, cannot be compared to the energy actually required for the removal of the outer electrons, because relaxation is not accounted for. An accurate energy expression has also been derived, [Formula: see text] which measures the actual withdrawal of the valence electrons. The latter expression requires the use of discrete values of Nc, the number of electrons assigned to the core, namely Nc = 2 for the first-row and Nc = 10 e for the second-row elements. Keywords: atoms, core–valence separation.

Observations of the Eyewall Structure of Typhoon Sinlaku (2008) during the Transformation Stage of Extratropical Transition

2014 ◽  
Vol 142 (9) ◽  
pp. 3372-3392 ◽  
Author(s):  
Annette M. Foerster ◽  
Michael M. Bell ◽  
Patrick A. Harr ◽  
Sarah C. Jones
Keyword(s):  
Tropical Cyclones ◽  
Wind Shear ◽  
Doppler Radar ◽  
Vertical Wind Shear ◽  
Core Region ◽  
Vertical Wind ◽  
Naval Research ◽  
Extratropical Transition ◽  
The Core ◽  
Transformation Stage

A unique dataset observing the life cycle of Typhoon Sinlaku was collected during The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC) in 2008. In this study observations of the transformation stage of the extratropical transition of Sinlaku are analyzed. Research flights with the Naval Research Laboratory P-3 and the U.S. Air Force WC-130 aircraft were conducted in the core region of Sinlaku. Data from the Electra Doppler Radar (ELDORA), dropsondes, aircraft flight level, and satellite atmospheric motion vectors were analyzed with the recently developed Spline Analysis at Mesoscale Utilizing Radar and Aircraft Instrumentation (SAMURAI) software with a 1-km horizontal- and 0.5-km vertical-node spacing. The SAMURAI analysis shows marked asymmetries in the structure of the core region in the radar reflectivity and three-dimensional wind field. The highest radar reflectivities were found in the left of shear semicircle, and maximum ascent was found in the downshear left quadrant. Initial radar echos were found slightly upstream of the downshear direction and downdrafts were primarily located in the upshear semicircle, suggesting that individual cells in Sinlaku’s eyewall formed in the downshear region, matured as they traveled downstream, and decayed in the upshear region. The observed structure is consistent with previous studies of tropical cyclones in vertical wind shear, suggesting that the eyewall convection is primarily shaped by increased vertical wind shear during step 2 of the transformation stage, as was hypothesized by Klein et al. A transition from active convection upwind to stratiform precipitation downwind is similar to that found in the principal rainband of more intense tropical cyclones.

A Climatological Analysis of Ambient Deep-Tropospheric Vertical Wind Shear Impacts upon Tornadoes in Tropical Cyclones

2020 ◽  
Vol 35 (5) ◽  
pp. 2033-2059
Author(s):  
Benjamin A. Schenkel ◽  
Roger Edwards ◽  
Michael Coniglio
Keyword(s):  
Tropical Cyclones ◽  
Wind Shear ◽  
Inner Core ◽  
Deep Convection ◽  
Outer Region ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Near Surface ◽  
Thermodynamic Instability ◽  
Left Quadrant

AbstractThe cyclone-relative location and variability in the number of tornadoes among tropical cyclones (TCs) are not completely understood. A key understudied factor that may improve our understanding is ambient (i.e., synoptic-scale) deep-tropospheric (i.e., 850–200-hPa) vertical wind shear (VWS), which impacts both the symmetry and strength of deep convection in TCs. This study conducts a climatological analysis of VWS impacts upon tornadoes in TCs from 1995 to 2018, using observed TC and tornado data together with radiosondes. TC tornadoes were classified by objectively defined VWS categories, derived from reanalyses, to quantify the sensitivity of tornado frequency, location, and their environments to VWS. The analysis shows that stronger VWS is associated with enhanced rates of tornado production—especially more damaging ones. Tornadoes also become localized to the downshear half of the TC as VWS strengthens, with tornado location in strongly sheared TCs transitioning from the downshear-left quadrant in the TC inner core to the downshear-right quadrant in the TC outer region. Analysis of radiosondes shows that the downshear-right quadrant in strongly sheared TCs is most frequently associated with sufficiently strong near-surface speed shear and veering aloft, and lower-tropospheric thermodynamic instability for tornadoes. These supportive kinematic environments may be due to the constructive superposition of the ambient and TC winds, and the VWS-induced downshear enhancement of the TC circulation among other factors. Together, this work provides a basis for improving forecasts of TC tornado frequency and location.

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