52 ACTA METEOROLOGICA SINICA VOL.19 The Eect of Asymmetric Wind Structures of Tropical Cyclones on Their Tracks

A model is proposed relating a variety of factors of tropical cyclones (TCs) to their tracks, and attentions are paid to the in uence of the asymmetric wind structures of TCs. Ideal numerical calculation shows that the asymmetric wind structures of TCs have conspicuous in uence on their motion tracks. When moving due westward initially, an axisymmetric TC will de ect right, and the overall trend is eastward. When it is asymmetric but the asymmetry is not sharp, wherever the area of maximum wind is, the TC de ects northwest rst, and then, to various areas depending on the positions of the areas of maximum wind, i.e. for the area of maximum wind in Quadrant I, to the southeast; for in Quadrant II, to the northeast; for in Quadrant III, to the northwest; for in Quadrant IV, to the southwest. And in the above four cases, the TC tracks are all accompanied by clockwise looping motions. With the asymmetry of the TC intensiying, the track of the TC motion will be stretched further. For the area of maximum wind in Quadrants I and II, the TC tracks are still accompanied by clockwise looping motions; for the area of maximum wind in Quadrants III and IV, the TC tracks become oscillatory, without clockwise looping motions. Key words: tropical cyclone, asymmetric wind structure, tracks of tropical cyclones 1