The Effects of Vertical Wind Shear on the Distribution of Convection in Tropical Cyclones

Corbosiero, Kristen L.; Molinari, John

doi:10.1175/1520-0493(2002)130<2110:teovws>2.0.co;2

Cited by 303 publications

(241 citation statements)

References 34 publications

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“…By contrast, corresponding uniform-flow experiments tend to produce more symmetric rainfall pattern (not shown), suggesting that the ambient vertical shear is responsible for the asymmetric convective heating. Previous modeling studies with convective heating (Wang and Holland 1996a;Bender 1997), and observational studies (Franklin et al 1993;Corbosiero and Molinari 2002;Black et al 2002) also suggest that convective asymmetries in tropical cyclones are closely related to vertical wind shear. Frank and Ritchie (2001) speculated that differential vorticity advection with height caused by the shear could be the mechanism responsible for the asymmetry.…”

Section: Simulated Tracksmentioning

confidence: 87%

“…However, there is no consensus about the role of convective asymmetries in tropical cyclones. Corbosiero and Molinari (2002) speculated, based on their observational study, that asymmetric convection is excited so as to minimize tropical cyclone tilt in the inner core. On the other hand, Wu and Wang (2001, hereafter referred to as WW) and Chan et al (2002) argued that convective asymmetries could play an active role in TC motion, rather than a mere response to vertical shear.…”

Section: Introductionmentioning

confidence: 99%

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Steering Weight Concept and its Application to Tropical Cyclones Simulated in a Vertical Shear Experiment

Ueno

2003

Journal of the Meteorological Society of Japan

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A series of idealized numerical simulations of tropical cyclones is performed to enhance the knowledge on the mechanism of tropical cyclone (TC) motion in vertically sheared environments. The simulations are performed using an f -plane version of the typhoon track prediction model previously run at the Japan Meteorological Agency.A wide variety of TC tracks show up when the model is integrated repeatedly with different formulations of convective parameterization from an identical initial field. To account for the diversity of TC motion in vertically sheared environment, a steering-weight concept is introduced. The steeringweight is a set of weighting factors, mathematically derived from the surface pressure tendency equation, and can be a measure of how sensitive the motion of a TC is, to the steering flow at each vertical level. The experiments with different cumulus parameterizations show that the vertical profile of steering weight tends to strongly depend on the cumulus parameterization scheme used, but much less on the environment specified. This result implies that the axisymmetric thermal structure of modeled TCs, is mostly determined by parameterization schemes rather than environment in the model. And the longterm (say, 72 h mean) TC motion is well explained by the combination of steering weight, and large-scale flow fields.The result suggests that the differences in TC track among numerical prediction models, may be attributable to the differences in steering weight to some degree, given that there is no significant difference in the simulated large-scale flow fields among the models. Moreover, as long as the steering weight concept holds in nature, the steering-weighted deep layer mean flow, instead of the conventional and empirical pressure-weighted one, would work better in accounting for the motion of real tropical cyclones.

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Section: Simulated Tracksmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Steering Weight Concept and its Application to Tropical Cyclones Simulated in a Vertical Shear Experiment

Ueno

2003

Journal of the Meteorological Society of Japan

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“…A number of observational (e.g., Franklin et al 1993;Gamache et al 1997;Black et al 2002;Corbosiero and Molinari 2002, 2003), and modeling (e.g., Bender 1997Frank and Ritchie 2001;Rogers et al 2003;Ueno 2003) studies have shown a tendency for typhoonstrength vortices to develop upward motion, and/or produce precipitation, particularly in the eyewall, on the down-shear to downshearleft side of the storm. Among the observational studies, the most extensive one is the work of Corbosiero and Molinari, that used groundbased lightning data to evaluate the convective activities around TCs.…”

Section: Summary and Discussionmentioning

confidence: 99%

Observational Analysis and Numerical Evaluation of the Effects of Vertical Wind Shear on the Rainfall Asymmetry in the Typhoon Inner-Core Region

Ueno

2007

Journal of the Meteorological Society of Japan

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A number of observational and modeling studies have shown a tendency for typhoon strength vortices to develop upward motion and produce precipitation, particularly in the eyewall, on the downshear to downshear-left side of the tropical cyclones (TCs). However, the directional relationships obtained from the observational studies have been mostly confined to the TC cases in the Atlantic basin. Furthermore, little evidence has been presented so far for the relationship in magnitude, between shear and rainfall asymmetry.In the former part of the present study, the observational analysis on TC rainfall asymmetries is extended to the western North Pacific TCs in 2004, using the two types of rain-rate data, the RadarAMeDAS precipitation data, and satellite-based rainfall estimates, such as TMI and AMSR-E rain rates. It is well demonstrated from the analysis that rainfall in the inner-core region of a TC tends to occur on the downshear to downshear-left side, irrespective of data type used and latitudes where TCs are located. However, as far as the relationship between shear and storm motion is concerned, a sharp contrast is found between low and middle latitudes. In middle latitudes TCs have a tendency to move to the left of the shear, consistent with previous studies, while in low latitudes they tend to move to the right of the shear. The contrasting shear-relative storm heading between the two latitudes is attributed to the difference in vertical structure of the ambient wind.In the latter part of the study, to explore the quantitative relationship between shear and rainfall asymmetry, a formula for the shear-induced vertical motion is derived from the thermal wind balance equation for TC-like vortices. The formula states that the shear-induced vertical motion should be a function not only of shear magnitude, but also of vortex strength. To validate the formula a set of idealized numerical experiments are conducted, with realistic wind profiles, in which the initial environmental winds are specified from the 6-hourly JMA global analyses for two major typhoon cases in 2004. It is found from the numerical study that the magnitude of wavenumber-one vertical motion, predicted by the formula, is much more strongly correlated with that of model-produced rainfall asymmetry, than the shear alone, suggesting that the vortex strength is one of the main factors determining the magnitude of shear-induced rainfall asymmetry. The results from the idealized simulations also suggest that vortex tilt would have only a minor contribution to the rainfall asymmetry in the inner-core region, at least for well-developed TCs.

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“…Pastushkov, 1975;Corbosiero and Molinari, 2002;Lang et al, 2007;Ueno, 2007). The delayed initiation of convection is associated with a strong vertical wind shear (e.g.…”

Section: Introductionmentioning

confidence: 99%

Effects of vertical wind shear and cloud radiative processes on responses of rainfall to the large‐scale forcing during pre‐summer heavy rainfall over southern China

Shen

2011

Quart J Royal Meteoro Soc

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The pre-summer heavy rainfall over southern China during 3-8 June 2008 is simulated using a two-dimensional cloud-resolving model. The model is integrated with imposed zonally uniform vertical velocity, zonal wind, horizontal temperature and vapour advection from National Centers for Environmental Prediction (NCEP)/Global Data Assimilation System (GDAS) data. The effects of vertical wind shear and cloud radiative processes on the response of rainfall to largescale forcing are analysed through the comparison of two sensitivity experiments with the control experiment. One sensitivity experiment excludes the large-scale vertical wind shear and the other excludes the cloud radiative effects. During the decay phase of convection, the increase in model domain-mean surface rain-rate resulting from the exclusion of vertical wind shear is associated with the slowdown in the decrease of perturbation kinetic energy due to the exclusion of barotropic conversion from mean kinetic energy to perturbation kinetic energy. The increase in domain-mean rain-rate from the exclusion of cloud radiative effects is related to the enhancement of condensation and associated latent heat as a result of strengthened radiative cooling. The increase in the domain-mean surface rain-rate is mainly associated with the increase of convective rainfall, which is in turn related to the local atmospheric change from moistening to drying. During the onset and mature phases of convection, the domain-mean surface rain-rates are generally insensitive to vertical wind shear and cloud radiative effects whereas convective and stratiform rain-rates are sensitive to vertical wind shear and cloud radiative effects. The decrease in convective rain-rate and the increase in stratiform rain-rate are primarily associated with the enhanced transport of hydrometeor concentration from convective regions to raining stratiform regions. Copyright c 2011 Royal Meteorological Society Key Words: cloud-resolving model simulation; convective and stratiform rain-rates; vertical wind shear; cloud radiative effects; budget analysis

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The Effects of Vertical Wind Shear on the Distribution of Convection in Tropical Cyclones

Cited by 303 publications

References 34 publications

Steering Weight Concept and its Application to Tropical Cyclones Simulated in a Vertical Shear Experiment

Steering Weight Concept and its Application to Tropical Cyclones Simulated in a Vertical Shear Experiment

Observational Analysis and Numerical Evaluation of the Effects of Vertical Wind Shear on the Rainfall Asymmetry in the Typhoon Inner-Core Region

Effects of vertical wind shear and cloud radiative processes on responses of rainfall to the large‐scale forcing during pre‐summer heavy rainfall over southern China

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