Tsung-Yi Pan, Szu-Wei Chen, Chi-Shuin Liao, Kao-Hua Chang, Tsang-Jung Chang
Tuesday 30 june 2015
17:45 - 17:48h at North America (level 0)
Themes: (T) Extreme events, natural variability and climate change, (ST) Hydrological extremes: floods and droughts, Poster pitches
Parallel session: Poster pitches: 7I. Extreme - Flood Drought
Most big metropolises in the world are suffering some impacts of urbanization, and urban heat island effect is one of the issues about urbanization. Due to rapid economic growth and high population density in Taiwan metropolises, the urban heat island (UHI) effect has become more and more significant. Hence, the frequency of the extreme rainfalls increased results from the behavior of vertical convection in the atmosphere changed. For the purpose of preventing urban flood damage, this study evaluates the impacts of the urban heat island effect on extreme rainfalls in Taipei metropolitan. In order to identify the extreme rainfall events enhanced by the UHI effect, this study calculate the intensity of UHI (IUHI) for Taipei metropolitan to detect the relation between extreme rainfalls and UHI. Cluster analysis is adopted to separate the rainfall events into two groups based on IUHI, wind speed and the characteristics of rainfall events. Then, the variations of the spatial distribution and the temporal frequency analysis of the extreme rainfall events enhanced by the UHI effect are evaluated using statistical approaches. Furthermore, Weather Research and Forecasting model (WRF) is applied to simulate the temporal and spatial distributions of rainfall for various land-use types and various anthropogenic heat source conditions to validate the statistical results of UHI effect on extreme rainfalls. The results show that the durations of extreme rainfalls enhanced by the UHI effect are shorter than 6 hours, and high intensity of UHI and low wind speed provide a favorable environment for extreme rainfalls. Furthermore, the locations of the short-duration extreme rainfall events enhanced by the UHI effect move to southern area of Taipei metropolitan.