A Modeling Study on the Impacts of Typhoon Morakot's (2009) Vortex Structure on Rainfall in Taiwan Using Piecewise Potential Vorticity Inversion

Abstract

In this study, the impacts of Typhoon Morakot’s (2009) vortex structure on the extreme rainfall in Taiwan were investigated using piecewise potential vorticity (PV) inversion. The control (CTL) experiment, starting at 0000 UTC 7 August or 15 h before landfall, reproduced the event realistically and was validated against the observations. By altering the PV perturbation inside 750 km from its center, we conducted sensitivity experiments in which the size and circulation strength of TY Morakot were reduced/weakened in the initial field in several different ways. In the sensitivity tests, particularly those in which the initial PV within the inner core (≤ 250 km) was significantly weakened, the storm made landfall earlier, stayed over land longer, and exited Taiwan later. Such track changes were accompanied by a contraction and spin-up of the inner core at the early stages of the integration, Corresponding author: Shin-Yi Huang, Department of Earth Sciences, National Taiwan Normal University. No. 88, Sec. 4, Ting-Chou Rd., Taipei, 11677 Taiwan E-mail: hshinyi0828@gmail.com # The National Center for Atmospheric Research is sponsored by the National Science Foundation. J-stage Advance Published Date: 20 April 2020 Journal of the Meteorological Society of Japan Vol. 98, No. 4 708