The trochoid‐like track in Typhoon Dujuan (2003)

[1] The present study examines a prominent double eyewall case, namely, Typhoon Dujuan (2003) as it neared the island of Taiwan. This typhoon was unusual in that its double eye was not concentric. It has been suggested that vertical wind shear caused the inner eye to drift away from the typhoon circulation center. Thus, the inner eye tended to circulate due to the steering of the rotational flow in the moat with a period of 3.5 ∼ 4 h. The orbited inner eye motion superimposed on the typhoon motion as a whole resulted in a substantial oscillation, or wobble, and eventually manifested itself as a trochoid-like track. The orbiting inner eye also periodically produced additional abrupt wind increase up to 15 m s−1 for 1 ∼ 2 hour, and has been noted to be an important issue for nowcasting and hazard mitigations.