The Effects of the Heavy Rainfall Event of 12 June 2005 on Taiwan Terrain

• Main Author: Shui-Shang Chi Guo-Ji Jian
• Format: Article
• Language: English
• Published: Chinese Geoscience Union 2009-01-01
• Series: Terrestrial, Atmospheric and Oceanic Sciences
• Subjects: MCS; Torrential rain fall; Mei-Yu; WRF-ARW
• Online Access: http://tao.cgu.org.tw/images/attachments/v204p619.pdf

A series of numerical simulations are conducted using the Weather Re search and Fore casting (WRF-ARW) model with a 9-km mesh to examine the physical processes responsible for the torrential rain fall associated with a mesoscale convective system (MCS) along the Mei-Yu front that caused severe dam age over south western Taiwan on 12 June 2005. In the control experiment (with full Taiwan terrain), the MCS tends to prop a gate north ward along the wind ward (western) slope, rather than being advected down stream, as it encounters the southern Central Mountain Range (CMR). The low-level convergence between the dynamically-driven re turn flow and the in coming south westerly flow is an important factor for the north ward propagation of the MCS. The values of the un sat u rated moist Froude number (Fw) and the convective avail able potential energy (CAPE) are about 0.333 and 2858 J kg-1 for the convectively unstable basic flow. This air flow belongs to the flow-around regime as suggested by previous studies. In this flow regime, the torrential rain fall associated with the simulated MCS occurs on both the upslope side and adjacent plains over southwestern Taiwan, which agrees well with the observed rainfall distribution.