Two numerical simulations whose integration times are 144 h are performed using a linearized non-divergent barotropic vorticity equation model to investigation into the formation process of a wave train induced by the energy dispersion of a complex structure non-isolated vortex.In the initial field a tropical cyclone (TC) vortex and a mesoscale vortex coexist,which forms a complex structure pattern in the first simulation.
The results in the first simulation show that a TC-high-low wave train may be created by the energy dispersion of the complex structure non-isolated vortex.The formation of the wave train was composed of three stages: (1) an asymmetric structure in the east-west direction in the TC area emerged,(2) a high dispersion system occurred,was maintained and strengthened to the east of the TC vortex,and (3) a low dispersion system occurs and then intensifies to the east of the high dispersion system.
In the initial field there is only one tropical cyclone vortex,which forms an isolated circular vortex pattern rather then a complex structure pattern in the second simulation.The results in the second simulation show that a TC-high-low wave train can be identified.Compared with the case of the isolated circular vortex,three differences exhibit in the case of the complex structure vortex.Firstly,the first stage of the wave train formation is significantly shortened.Secondly,the dispersion high is stronger.Thirdly,the dispersion low has a larger spatial scale.
The results have following application prospects.
(1) TC is often located on the southern side of the subtropical high,the dispersion high system occurs on the east side of the TC,while TC moves from the east to the west under the influence of the steering flow.Sometimes the dispersion high can be connected with the subtropical high,which extends to the south,and TC track turns abruptly to the north from the west.In most cases,the subtropical high and the dispersion high is far away from each other,therefore they cannot be connected.The results in this paper show that the dispersion high is stronger in the case of complex structure configuration vortex,it will be in favor of their connection and leads to the unusual track of the TC.
(2) Normally there is less moisture with low probability of a new TC genesis in the dispersion high area,and vice versa.The results in this paper show that in the case of the complex structure vortex the dispersion low system extends to a large area,and the high probability region of a new TC genesis will be enlarged as well.