vortex merger
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Author(s):  
Xuliang Liu ◽  
Yong Luo ◽  
Shuhai Zhang ◽  
Hu Li ◽  
Zhaolin Fan ◽  
...  

2019 ◽  
Vol 94 (11) ◽  
pp. 115005
Author(s):  
Rupak Mukherjee ◽  
Akanksha Gupta ◽  
Rajaraman Ganesh

2019 ◽  
Vol 76 (8) ◽  
pp. 2335-2355 ◽  
Author(s):  
Warren P. Smith ◽  
Melville E. Nicholls

Abstract Recent numerical modeling and observational studies indicate the importance of vortical hot towers (VHTs) in the transformation of a tropical disturbance to a tropical depression. It has recently been recognized that convective-scale downdraft outflows that form within VHTs also preferentially develop positive vertical vorticity around their edges, which is considerably larger in magnitude than ambient values. During a numerical simulation of tropical cyclogenesis it is found that particularly strong low-level convectively induced vorticity anomalies (LCVAs) occasionally form as convection acts on the enhanced vorticity at the edges of cold pools. These features cycle about the larger-scale circulation and are associated with a coincident pressure depression and low-level wind intensification. The LCVAs studied are considerably deeper than the vorticity produced at the edges of VHT cold pool outflows, and their evolution is associated with persistent convection and vortex merger events that act to sustain them. Herein, we highlight the formation and evolution of two representative LCVAs and discuss the environmental parameters that eventually become favorable for one LCVA to reach the center of a larger-scale circulation as tropical cyclogenesis occurs.


2018 ◽  
Vol 75 (12) ◽  
pp. 4149-4173 ◽  
Author(s):  
Rosimar Rios-Berrios ◽  
Christopher A. Davis ◽  
Ryan D. Torn

Abstract A major open issue in tropical meteorology is how and why some tropical cyclones intensify under moderate vertical wind shear. This study tackles that issue by diagnosing physical processes of tropical cyclone intensification in a moderately sheared environment using a 20-member ensemble of idealized simulations. Consistent with previous studies, the ensemble shows that the onset of intensification largely depends on the timing of vortex tilt reduction and symmetrization of precipitation. A new contribution of this work is a process-based analysis following a shear-induced midtropospheric vortex with its associated precipitation. This analysis shows that tilt reduction and symmetrization precede intensification because those processes are associated with a substantial increase in near-surface vertical mass fluxes and equivalent potential temperature. A vorticity budget demonstrates that the increased near-surface vertical mass fluxes aid intensification via near-surface stretching of absolute vorticity and free-tropospheric tilting of horizontal vorticity. Importantly, tilt reduction happens because of a vortex merger process—not because of advective vortex alignment—that yields a single closed circulation over a deep layer. Vortex merger only happens after the midtropospheric vortex reaches upshear left, where the flow configuration favors near-surface vortex stretching, deep updrafts, and a substantial reduction of low-entropy fluxes. These results lead to the hypothesis that intensification under moderate shear happens if and when a “restructuring” process is completed, after which a closed circulation favors persistent vorticity spinup and recirculating warm, moist air parcels.


2017 ◽  
Vol 22 (5) ◽  
pp. 455-478 ◽  
Author(s):  
Xavier Carton ◽  
Mathieu Morvan ◽  
Jean N. Reinaud ◽  
Mikhail A. Sokolovskiy ◽  
Pierre L’Hegaret ◽  
...  

2017 ◽  
Vol 24 (5) ◽  
pp. 055705 ◽  
Author(s):  
W. C. Wan ◽  
G. Malamud ◽  
A. Shimony ◽  
C. A. Di Stefano ◽  
M. R. Trantham ◽  
...  

2016 ◽  
Vol 53 ◽  
pp. 116-127 ◽  
Author(s):  
Yaping Wang ◽  
Peiqing Liu ◽  
Tianxiang Hu ◽  
Qiulin Qu
Keyword(s):  

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Assaf Shimony ◽  
Dov Shvarts ◽  
Guy Malamud ◽  
Carlos A. Di Stefano ◽  
Carolyn C. Kuranz ◽  
...  

This paper brings new insights on an experiment, measuring the Kelvin–Helmholtz (KH) instability evolution, performed on the OMEGA-60 laser facility. Experimental radiographs show that the initial seed perturbations in the experiment are of multimode spectrum with a dominant single-mode of 16 μm wavelength. In single-mode-dominated KH instability flows, the mixing zone (MZ) width saturates to a constant value comparable to the wavelength. However, the experimental MZ width at late times has exceeded 100 μm, an order of magnitude larger. In this work, we use numerical simulations and a statistical model in order to investigate the vortex dynamics of the KH instability for the experimental initial spectrum. We conclude that the KH instability evolution in the experiment is dominated by multimode, vortex-merger dynamics, overcoming the dominant initial mode.


2016 ◽  
Vol 10 (1) ◽  
pp. 1-7
Author(s):  
Sanghyun Park ◽  
DongJin Sheen ◽  
Kyoungsik Chang ◽  
DongGi Kwag

2015 ◽  
Vol 110 (1) ◽  
pp. 1-22 ◽  
Author(s):  
X. Carton ◽  
D. Ciani ◽  
J. Verron ◽  
J. Reinaud ◽  
M. Sokolovskiy
Keyword(s):  

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