A further study of the tropical cyclone without parameterizing the effects of cumulus convection.

Yamasaki, Masanori

doi:10.2467/mripapers.34.221

Cited by 66 publications

(130 citation statements)

References 32 publications

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“…7, corresponded well to the results of numerical experiments by Yamasaki (1983Yamasaki ( , 1986. Using Yamasaki's (1983) convection categorization, it might be interpreted that TL1 and TL2 in the initial sub-stage belong to category I), LL1 to LL4 in the second sub-stage mainly belong to category II), SB1 and SB2 in the third and final sub-stages also belong mainly to category II), but they might belong to category III) after 12 UTC 31 August as the LLCC intensified. SB3 in the final sub-stage mainly belongs to category III).…”

Section: Precipitable Water Content Patternsupporting

confidence: 69%

“…After that, other almost circular spiral bands were formed and merged into each other to form an active round precipitation system around the typhoon center in the latter rapid developing stage (not shown). Yamasaki (1983) categorized the simulated convection in formation and intensification stages in an axially symmetric TC model, depending on the role of surface friction such that: I) surface friction does not play any significant role before the tangential velocity attains about 10 m/s, II) surface friction becomes important when the tangential velocity attains 10-15 m/s, and III) surface friction plays an essential role in the formation and maintenance of the eye and eyewall when the tangential velocity near the vortex center exceeds approximately 20 m/s. Further, Yamasaki (1986) performed a numerical experiment of TC development using a three-dimensional typhoon model based on the results of Yamasaki (1983), and pointed out that the structure of the simulated rainband depended on the developing stage of TC rotation and location of the rainband in the TC.…”

Section: Precipitable Water Content Patternmentioning

confidence: 99%

“…In Section 5, analysis will be focused on the long lasting intense MPF. In Section 6, characteristics of the MPFs on the early development of Yancy will be summarized and compared with those of numerically simulated mesoscale features in TC developments (Yamasaki, 1983(Yamasaki, , 1986 and several aspects of the long lasting intense MPF will be discussed. Summary and concluding remarks will be given in Section 7.…”

Section: Introductionmentioning

confidence: 99%

“…Yamasaki (1983) investigated the interaction between cumulus convection and large scale motion during the development of TC, using a two dimensional numerical model in which convection was treated explicitly, and categorized the simulated mesoscale convection in the developing TC three types depending on the role of surface friction. Further, Yamasaki (1986) developed a three-dimensional TC model with a new parameterization of convection based on the results of Yamasaki (1983) and performed a numerical experiment, in which the simulated mesoscale features were discussed using the category of convection, and compared them with several observational facts. Yamasaki (1989) studied tropical cyclone formation in the intertropical convergence zone (ITCZ).…”

Section: Introductionmentioning

confidence: 99%

“…For substantiation of the formation and early development TC process in the context of interaction between convection and larger-scale motions (Yamasaki, 1983(Yamasaki, , 1986(Yamasaki, , 1988, it is important to investigate how the convection is organized within a TC in the early developing stage based on continuous radar observation.…”

Section: Introductionmentioning

confidence: 99%

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Structure and Evolution of Convection within Typhoon Yancy (T9313) in the Early Developing Stage Observed by the Keifu Maru Radar

Mori¹,

Ishigaki²,

Maehira³

et al. 1999

Journal of the Meteorological Society of Japan

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Typhoon Yancy (T9313), which was in the early gradual developing stage and moved westward over the northwestern Pacific near (19N, 129E), was observed by the Japan Meteorological Agency research vessel Keifu Maru, during 30 August to 1 September 1993. During that period, the circulation center of Yancy approached as close as 80 km to the north of the Keifu Maru. Convection in the major part of Yancy was analyzed using the radar, maritime weather and upper air observation data obtained on the ship and recently available satellite data. Cell echo tracking winds (CETwinds) were estimated and utilized to supplement low level wind data around Yancy.During the early developing stage, an in-concentric structure of Yancy in which a cloud system existed in a southwest quadrant of a lower-level cyclonic circulation (LLCC) of 1500 km scale was transformed to a concentric one through a formation of a central dense overcast ('CDO') in the cloud system. After the establishment of the concentric structure, Yancy began rapid development.Various mesoscale (100-500 km) precipitation features (MPFs) were organized and evolved successively within Yancy. The configurations of the MPFs were changed as the early developing process progressed through four sub-stages. In the initial sub-stage, a large (400 km) echo system (LES) was organized in the southwest quadrant of the LLCC, over which a round cloud system appeared. In the second sub-stage, a long lasting mesoscale intense convective area (MICA) was formed around the northwestern edge of the LES, which was a mesoscale precipitation entity of the 'CDO' in the round cloud system. LLCC appeared to be intensified on a 500 km scale after the formation of MICA. In the third sub-stage, LES and the cloud system evolved into a comma-shaped spiral band with length over 500 km in the intense cyclonic circulation. In the final sub-stage, curvature of the spiral band was increased and an inner near-circular spiral band emerged in the further intensified LLCC. The northern head of the comma-shaped cloud system was encircling the LLCC center. Line systems transversal and longitudinal to lower-level circulation were formed around MICA in the first sub-stage, and in the second sub-stage, respectively.

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Section: Precipitable Water Content Patternsupporting

confidence: 69%

Section: Precipitable Water Content Patternmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure and Evolution of Convection within Typhoon Yancy (T9313) in the Early Developing Stage Observed by the Keifu Maru Radar

Mori¹,

Ishigaki²,

Maehira³

et al. 1999

Journal of the Meteorological Society of Japan

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The effects of vortex structure and vortex translation on the tropical cyclone boundary layer wind field

Williams

2015

J Adv Model Earth Syst

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The effects of vortex translation and radial vortex structure in the distribution of boundary layer winds in the inner core of mature tropical cyclones are examined using a high-resolution slab model and a multilevel model. It is shown that the structure and magnitude of the wind field (and the corresponding secondary circulation) depends sensitively on the radial gradient of the gradient wind field above the boundary layer. Furthermore, it is shown that vortex translation creates low wave number asymmetries in the wind field that rotate anticyclonically with height. A budget analysis of the steady state wind field for both models was also performed in this study. Although the agradient force drives the evolution of the boundary layer wind field for both models, it is shown that the manner in which the boundary layer flow responds to this force differs between the two model representations. In particular, the inner core boundary layer flow in the slab model is dominated by the effects of horizontal advection and horizontal diffusion, leading to the development of shock structures in the model. Conversely, the inner core boundary layer flow in the multilevel model is primarily influenced by the effects of vertical advection and vertical diffusion, which eliminates shock structures in this model. These results further indicate that special care is required to ensure that qualitative applications from slab models are not unduly affected by the neglect of vertical advection.

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Shock‐like structures in the tropical cyclone boundary layer

Williams

Taft

McNoldy

et al. 2013

J Adv Model Earth Syst

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[1] This paper presents high horizontal resolution solutions of an axisymmetric, constant depth, slab boundary layer model designed to simulate the radial inflow and boundary layer pumping of a hurricane. Shock-like structures of increasing intensity appear for category 1-5 hurricanes. For example, in the category 3 case, the u @u=@r ð Þ term in the radial equation of motion produces a shock-like structure in the radial wind, i.e., near the radius of maximum tangential wind the boundary layer radial inflow decreases from approximately 22 m s 21 to zero over a radial distance of a few kilometers. Associated with this large convergence is a spike in the radial distribution of boundary layer pumping, with updrafts larger than 22 m s 21 at a height of 1000 m. Based on these model results, it is argued that observed hurricane updrafts of this magnitude so close to the ocean surface are attributable to the dry dynamics of the frictional boundary layer rather than moist convective dynamics. The shock-like structure in the boundary layer radial wind also has important consequences for the evolution of the tangential wind and the vertical component of vorticity. On the inner side of the shock the tangential wind tendency is essentially zero, while on the outer side of the shock the tangential wind tendency is large due to the large radial inflow there. The result is the development of a U-shaped tangential wind profile and the development of a thin region of large vorticity. In many respects, the model solutions resemble the remarkable structures observed in the boundary layer of Hurricane Hugo (1989).

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A further study of the tropical cyclone without parameterizing the effects of cumulus convection.

Cited by 66 publications

References 32 publications

Structure and Evolution of Convection within Typhoon Yancy (T9313) in the Early Developing Stage Observed by the Keifu Maru Radar

Structure and Evolution of Convection within Typhoon Yancy (T9313) in the Early Developing Stage Observed by the Keifu Maru Radar

The effects of vortex structure and vortex translation on the tropical cyclone boundary layer wind field

Shock‐like structures in the tropical cyclone boundary layer

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