Impact of radius of TC intensity correction on No.1618 TC track prediction

The mean track error of the 18th tropical cyclone (TC) in 2016 (noted as TC 1618) predicted by the regional typhoon model GRAPES_TYM is much larger compared to that of all other TC forecasts in that year. The impact of vortex initialization scheme including vortex relocation and intensity correction is tested in this paper. The results show that vortex intensity correction is the main factor that causes the large mean track error. The sensitivity study of the impacts of different radii (r₀=12°, 9°, 6°, 3°) of vortex intensity correction on the forecast track is further carried out. The results show that the larger the radius of intensity correction is, the bigger the mean track error would be. A larger intensity correction radius will produce a faster moving speed and larger moving direction error. Examinations of the subtropical high and the size of TC vortex in the mean sea level pressure field reveal that a larger intensity correction radius produces a larger TC vortex and a weaker subtropical high adjacent to the TC circulation in the initial time; the larger TC vortex moves northward faster, sustains the larger size of vortex and the weaker subtropical high to the north of the TC during integration. Eventually the larger vortex moves into the westerly trough earlier.