| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 100 === In order to understand the situations that rainfall and temperature may change in the future under the influence of climate change in Taiwan, this research develops a two-step statistical downscaling model (TSSDM) combining space downscaling model (SDM) and time downscaling model (TDM) with sampling theory.
In this research, the meteorological stations of Tamsui, Taichung, Kaohsiung and Hualien are employed as cases studies. The rainfall and temperature data from the Central Weather Bureau (CWB), and the meteorological factors from General Circulation Models are collected first. Then the TSSDM is built within two stage: in the first stage, SDM is constructed by combining the radial basis function neural network (RBFNN) and the genetic algorithm (GA); in the second stage, with the historical daily rainfall data and future monthly rainfall data obtained from SDM, TDM is constructed using the concept of probability distribution to simulate future daily rainfall data. Meanwhile, the Bootstrap sampling method is used to estimate the uncertainty of SDM model. Finally, the future simulated daily rainfall by TSSDM model and by change factors (CF) method are compared to assess the uncertainty of future rainfall.
Simulated results show that projected average monthly rainfall of Tamsui, Taichung, Kaohsiung and Hualien meteorological stations in the short, medium and long-term fall in 150 to 170 millimeter, 70 to 186 millimeter, 70 to 380 millimeter and 80 to 240 millimeter, respectively. The monthly rainfall difference between summer and winter in the short, medium and long-term are 41.55 millimeter, 50.87 millimeter and 42.54 millimeter in Tamsui meteorological station; 7.67 millimeter, -5.88 millimeter and -25.00 millimeter in Taichung meteorological station; 1.28 millimeter, -8.63 millimeter and -12.27 millimeter in Kaohsiung meteorological station; -15.54 millimeter, -35.96 millimeter and -45.96 millimeter in Hualien meteorological station. Projected average and maximum daily rainfall during January have similar tendency to historical data in Tamsui meteorological station, but have increasing one otherwise. Projected average and maximum daily rainfall increase in July in Tamsui meteorological station, having similar tendency to historical data in Taichung meteorological station, but decrease otherwise.
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