Western North Pacific Typhoons with Concentric Eyewalls

Kuo, Hung‐Chi; Chang, C. P.; Yang, Yi-Ting; Jiang, Hau-Jang

doi:10.1175/2009mwr2850.1

Cited by 85 publications

(91 citation statements)

References 21 publications

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“…Compared to the previous studies [4,15,16,22], we find three characteristics consistent with the classic ERC theory as follows: (1) the structure of the sea surface wind field is axisymmetric; (2) the intensity of the primary eyewall is smaller than the secondary eyewall; and (3) the primary eyewall is replaced by the secondary eyewall. We suggest that the axisymmetric structure plays a major role in the ERC dynamic process.…”

Section: Discussionsupporting

confidence: 82%

“…Therefore, the role of the axisymmetric double-eye structure in the ERC dynamic process is verified as consistent with the classic theory [15,16]. Moreover, many hurricanes are detected not to significantly weaken after the formation of the secondary eyewall [22], which may be a result of the asymmetric hurricane structure [13]. As Hurricane Bertha (2008) is relatively axisymmetric, the SFMR observed in one-dimension is supposed to represent the surface wind.…”

Section: Discussionsupporting

confidence: 75%

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Symmetric Double-Eye Structure in Hurricane Bertha (2008) Imaged by SAR

Zhang¹,

Perrie²

2018

Remote Sensing

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Abstract:Internal dynamical processes play a critical role in hurricane intensity variability. However, our understanding of internal storm processes is less well established, partly because of fewer observations. In this study, we present an analysis of the hurricane double-eye structure imaged by the RADARSAT-2 cross-polarized synthetic aperture radar (SAR) over Hurricane Bertha (2008). SAR has the capability of hurricane monitoring because of the ocean surface roughness induced by surface wind stress. Recently, the C-band cross-polarized SAR measurements appear to be unsaturated for the high wind speeds, which makes SAR suitable for studies of the hurricane internal dynamic processes, including the double-eye structure. We retrieve the wind field of Hurricane Bertha (2008), and then extract the closest axisymmetric double-eye structure from the wind field using an idealized vortex model. Comparisons between the axisymmetric model extracted wind field and SAR observed winds demonstrate that the double-eye structure imaged by SAR is relatively axisymmetric. Associated with airborne measurements using a stepped-frequency microwave radiometer, we investigate the hurricane internal dynamic process related to the double-eye structure, which is known as the eyewall replacement cycle (ERC). The classic ERC theory was proposed by assuming an axisymmetric storm structure. The ERC internal dynamic process of Hurricane Bertha (2008) related to the symmetric double-eye structure here, which is consistent with the classic theory, is observed by SAR and aircraft.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionsupporting

confidence: 75%

Symmetric Double-Eye Structure in Hurricane Bertha (2008) Imaged by SAR

Zhang¹,

Perrie²

2018

Remote Sensing

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“…For example, after the eyewall replacement cycle is completed, usually a larger eye results that modifies the inner-to-outer wind structure. When there is a concentric eyewall, a secondary wind maximum will be found in the radial wind profile (Willoughby et al 1982;Kossin and Sitkowski 2009;Kuo et al 2009), and again this affects the TC size. The situation is similar in the formation of annular storms although the occurrence frequency is just a few percent of all storms (Knaff et al 2003(Knaff et al , 2008.…”

Section: Other Factors Affecting Tc Sizementioning

confidence: 99%

Initial Maintenance of Tropical Cyclone Size in the Western North Pacific

Lee

Cheung

Fang

et al. 2010

Monthly Weather Review

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A tropical cyclone (TC) size parameter, which is defined here as the radius of 15 m s 21 near-surface wind speed (R15), is calculated for 145 TCs in the western North Pacific during 2000-05 based on QuikSCAT oceanic winds. For the 73 TCs that intensified to typhoon intensity during their lifetimes, the 33% and 67% respective percentiles of R15 at tropical storm intensity and at typhoon intensity are used to categorize small, medium, and large TCs. Whereas many of the small TCs form from an easterly wave synoptic pattern, the monsoon-related formation patterns are favorable for forming medium to large TCs. Most of these 73 TCs stay in the same size category during intensification, which implies specific physical mechanisms for maintaining TC size in the basin. The 18 persistently large TCs from the tropical storm to the typhoon stage mostly have northwestward or north-northwestward tracks, while the 16 persistently small TCs either move westwardnorthwestward in lower latitudes or develop at higher latitudes with various track types. For the large TCs, strong low-level southwesterly winds exist in the outer core region south of the TC center throughout the intensification period. The small TCs are more influenced by the subtropical high during intensification. The conclusion is that it is the low-level environment that determines the difference between large and small size storms during the early intensification period in the western North Pacific.

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“…This cycle often produces an oscillation of the hurricane's maximum intensity while serving as a mechanism for storm growth. These intensity and structure changes have been well studied (Willoughby et al 1982;Willoughby 1988Willoughby , 1990Black and Willoughby 1992;Dodge et al 1999;Hawkins et al 2006;Houze et al 2006Houze et al , 2007Maclay et al 2008;Kuo et al 2009;Sitkowski et al 2011, hereafter SKR11;Zhou and Wang 2011;Kossin and Sitkowski 2012).…”

Section: Introductionmentioning

confidence: 99%

Hurricane Eyewall Replacement Cycle Thermodynamics and the Relict Inner Eyewall Circulation

Sitkowski

Kossin

Rozoff

et al. 2012

Monthly Weather Review

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Flight-level aircraft data are used to examine inner-core thermodynamic changes during eyewall replacement cycles (ERCs) and the role of the relict inner eyewall circulation on the evolution of a hurricane during and following an ERC. Near the end of an ERC, the eye comprises two thermodynamically and kinematically distinct air masses separated by a relict wind maximum, inside of which high inertial stability restricts radial motion creating a ''containment vessel'' that confines the old-eye air mass. Restricted radial flow aloft also reduces subsidence within this confined region. Subsidence-induced warming is thus focused along the outer periphery of the developing post-ERC eye, which leads to a flattening of the pressure profile within the eye and a steepening of the gradient at the eyewall. This then causes a local intensification of the winds in the eyewall. The cessation of active convection and subsidence near the storm center, which has been occurring over the course of the ERC, leads to an increase in minimum pressure. The increase in minimum pressure concurrent with the increase of winds in the developing eyewall can create a highly anomalous pressure-wind relationship. When the relict inner eyewall circulation dissipates, the air masses are free to mix and subsidence can resume more uniformly over the entire eye.

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Western North Pacific Typhoons with Concentric Eyewalls

Cited by 85 publications

References 21 publications

Symmetric Double-Eye Structure in Hurricane Bertha (2008) Imaged by SAR

Symmetric Double-Eye Structure in Hurricane Bertha (2008) Imaged by SAR

Initial Maintenance of Tropical Cyclone Size in the Western North Pacific

Hurricane Eyewall Replacement Cycle Thermodynamics and the Relict Inner Eyewall Circulation

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