HR: 1330h
AN: A43A-04    [Abstracts]
TI: The use of WRF model to Investigate Rainshowers and Flooding in Taiwan during the Monsoon Break Period
AU: * Lin, P
EM: tliam@atm.ncu.edu.tw
AF: National Central University, Department of Atmos. Sciences,300 Jhong-Da Road, Jhong-Li, 32054 Taiwan
AU: Chen, C
EM: tchencs@atm.ncu.edu.tw
AF: National Central University, Department of Atmos. Sciences,300 Jhong-Da Road, Jhong-Li, 32054 Taiwan
AU: Chen, C
EM: tliam@atm.ncu.edu.tw
AF: National Central University, Department of Atmos. Sciences,300 Jhong-Da Road, Jhong-Li, 32054 Taiwan
AU: Lin, H
EM: tliam@atm.ncu.edu.tw
AF: National Central University, Department of Atmos. Sciences,300 Jhong-Da Road, Jhong-Li, 32054 Taiwan
AB: A rainfall minimum is normally observed in Taiwan between the end of the Mei-Yu season and the end of June, a part of the monsoon break. Nevertheless,rainshowers still occurred ocasionally during that period. On 20 June 2000, more than 100 mm/day rainfall were observed at several stations on the lower slops in northern Taiwan. Flooding is unusual in most of Taiwan during the monsoon break period. However, flash floodd occurred in central and southern Taiwan on 2-4 July 2004 during the climatological minimum rainfall period. This event was initialized by typhoon Mindulle and by mesoscale convective systems embedded in the southwesterly flow that followed the passage of the typhoon over Taiwan.The maximun daily rainfall was more than 500 mm over Taiwan during that period. In this paper we use the WRF model to investigate rainshowers and flash flooding cases during the monsoon break in Taiwan. The simulation results suggest that a convergence zone formed over the leeward side of northern Taiwan due to a split in the prevailing flow from south. This convergence was enhanced by the onshore and upslope wind. When an updraft forms on the downwind side of heated mountain sloped, and moveds in to the convergence area heavy rainshower occurs. The preliminary results, forecasting the heavy rainfall associated with typhoon and the MCSs, show great promising. The heavy rainfall pattern and its evolution can be captured well by the WRF model. The confluene of the northwesterly flow associated with Mindulle and the wide-spread southwesterly flow, initiated the formation of MCSs. These MCSs moved into the costal area and the dynamic effect of the mountain range resulted in continuous heavy rainfall in the central and southern Taiwan. The microphysical process and the dynamical effects play by the central mountain range will be discussed in this study.
DE: 3210 Modeling
DE: 3300 METEOROLOGY AND ATMOSPHERIC DYNAMICS
DE: 4255 Numerical modeling
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly