A Classification of Binary Tropical Cyclone–Like Vortex Interactions*

Abstract

The interaction between two tropical cyclones with different core vorticities and different sizes is studied with the aid of a nondivergent barotropic model, on both the f plane and the sphere. A classification of a wide range of cases is presented, using the Dritschel-Waugh scheme, which subdivides vortex interactions into five types: elastic interaction, partial straining out, complete straining out, partial merger, and complete merger. The type of interaction for a vortex pair on the f plane, and the same pair on the sphere, was the same for 77 out of 80 cases studied. The primary difference between the results on the f plane and those on the sphere is that the vorticity centroid of the pair is fixed on the f plane but can drift a considerable distance poleward and westward on the sphere. In the spherical case, the interaction between the cyclone pair and the associated ␤induced cyclonic and anticyclonic circulations can play an important role. The ''partial merger'' regime is studied in detail. In this regime the interaction between vortices can lead to episodic exchanges of vorticity, with both vortices surviving and entering a stage of continued but weaker interaction. With the aid of passive tracers, it is found that the exchange of vorticity is restricted to the vortex periphery even when the vorticity field within each vortex is flat, so that the vortex core is the last region to be eroded. It is hypothesized that some observed interacting tropical cyclones actually do undergo this partialmerger process.

The Formation of Concentric Vorticity Structures in Typhoons

“…There are many documented cases of binary tropical cyclone interactions that resemble the theoretical work of Dritschel and Waugh (1992) (e.g., see Larson 1975, Lander and Holland 1993, Kuo et al 2000, Prieto et al 2003. The complete straining out regime of the binary vortex interaction in Dritschel and Waugh (1992) shows a small, weaker vortex being sheared out into thin filaments of vorticity surrounding the large, stronger vortex with no incorporation into the large vortex.…”

Lagrangian coherent structures in tropical cyclone intensification

“…Whereas the VHT interaction is clearly more complex than the evolution of a single mature hurricane vortex, the coordinate system proposed by Rutherford and Dangelmayr (2010) nonetheless resolves LCSs under shorter timescales. We note that other studies (Truesdell, 1954;Saffman, 1981;Provenzale, 1999;Prieto et al, 2003;Shadden et al, 2006) have investigated the interaction between and entrainment of particles by vortices using different methods, while the ridges of FTLE fields in relation to two vortices was studied by Lapeyre (2002).…”

Analyzing the Adaptive Mesh Refinement (AMR) Characteristics of a High-Order 2D Cubed-Sphere Shallow-Water Model

“…Though the cells at panel edges are conformal with neighboring cells across panel boundaries, DECEMBER 2016the transition between the panels is not smooth due to the separate mapping on each panel. To preserve the order of accuracy of the fluxes, the domain is expanded at the panel edges with the addition of three layers of ghost cells to perform the FV calculations on each panel.…”

“…These interactions were first studied by Fujiwhara (Fujiwhara 1921) and are commonly called the Fujiwhara effect. Idealized binary-vortex interactions have been extensively investigated using 2D idealized models by Melander et al (1988), Waugh (1992), Ritchie and Holland (1993), Prieto et al (2003), and Shin et al (2006). A majority of the research has been conducted on two-dimensional Cartesian systems using a constant Coriolis force.…”