Numerical Analysis on the Effects of Binary Interaction between Typhoons Tembin and Bolaven in 2012

Zhipeng Xian,Keyi Chen

doi:10.1155/2019/7529263

Abstract

The binary interaction is one of the most challenging factors to improve the forecast accuracy of multiple tropical cyclones (TCs) in close vicinity. The effect of binary interaction usually results in anomalous track and variable intensity of TCs. A typical interaction type, one-way influence mode, has been investigated by many studies which mainly focused on the anomalous track and record-breaking precipitation, such as typhoons Morakot and Goni. In this paper, a typical case of this type, typhoons Tembin and Bolaven, occurred in the western North Pacific in August 2012, was selected to study how one typhoon impacts the track and intensity of the other one. The vortex of Tembin or Bolaven and the monsoon circulation were removed by a TC bogus scheme and a low-pass Lanczos filter, respectively, to carry out the numerical experiments. The results show that the presence of monsoon made the binary interaction more complex by affecting the tracks and the translation speeds of the TCs. The influence of Bolaven on the track of Tembin was more significant than the influence of Tembin on the track of Bolaven, and the looping track of Tembin was also affected by the external surrounding circulation associated with Bolaven. The absence of Tembin was not conducive to the development of Bolaven due to stronger vertical wind shear condition and the less kinetic energy being transported to upper troposphere. Note that the above analysis demonstrates the interacting processes between TCs and sheds some light on the prediction of binary TCs.

Highlights

Brand [2], who analyzed the relationship between angular change and separation distance for 22 pairs of binary typhoons in the western North Pacific, suggested that the binary typhoon effect was related to the scale and intensity of typhoons and further indicated that two typhoons start to rotate when the separation distance is less than 750 miles
Wu et al [8] drew an opposite conclusion for the same binary typhoons case. ey carried out a set of experiments with modifying the intensity of Morakot in its initial conditions to evaluate the factors affecting the interaction between the two tropical cyclones (TCs). e results showed that Morakot had a greater impact on the motion and was conducive to intensifying the strength of Goni, whereas Goni, located upstream of the southwesterly flow, intercepted part of the water vapor being transported to Morakot, making Morakot weaken
Synoptic Situation Analysis. e synoptic evolution was shown by the 500 hPa geopotential height elds from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalyses data from 0000 UTC 24 August to 0000 UTC 27 August (Figure 2). ere were one trough and one ridge in midhigh latitudes regions locating in China and Japan, respectively. e circulation center of subtropical high was located in the ocean and extended westward from 0000 UTC August to 0000 UTC August, with the westernmost contours of 576 dagpm locating at 110°E

Summary

Introduction

The model succeeded well in simulating the tracks of Tembin and Bolaven in the CTL experiment, especially Tembin’s looping track, but the translation speed of the two typhoons (in white circle) was faster than the best track. Ese results suggest that the monsoon had an impact on both the tracks and the translation speeds of the TCs, especially for the smaller vortex of Tembin which was a ected by both the existence of Bolaven.

Results

Conclusion