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題 名 | 應用ENSO指標建立乾旱機率預報模式--以臺灣南部地區為例=Development of Drought Probability Forecasting Models Based on ENSO Indices--A Case Study in Southern Taiwan |
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作 者 | 郭志豪; 楊道昌; 郭振民; 陳憲宗; 游保杉; | 書刊名 | 農業工程學報 |
卷 期 | 58:1 2012.03[民101.03] |
頁 次 | 頁13-32 |
分類號 | 328.633 |
關鍵詞 | 標準化降雨指標; 狀態轉移機率; 多模式系集; 乾旱機率預報; Standardized precipitation index; ENSO; State transition probability; Multi-model ensemble; Drought probability forecasting; |
語 文 | 中文(Chinese) |
中文摘要 | 有鑑於台灣降雨時空分配不均,尤其是降雨量不足的氣候型態導致水源短缺, 可用水資源分配與管理不易,乾旱現象愈漸嚴重。本研究首先建立台灣南部區域連 續三個月累積雨量之標準化降雨指標(standardized precipitation index, SPI3),配合由 「聖嬰-南方振盪(El Nino-Southern Oscillation, ENSO)」所造成太平洋環流區域之大 尺度氣候型態改變的環流資訊,並參考馬可夫鏈之狀態轉移機率的概念,由不同變 數的間隔範圍計算其發生次數,以建置不同ENSO 相關指標狀態下轉移至SPI3 的機 率分布矩陣。再藉由所建置的狀態轉移機率矩陣予以建立乾旱機率預報模式。本研 究進一步以多模式系集(multi-model ensemble, MME)機率預報的概念,由ENSO 相關 指標資訊所處的狀態,預測台灣南部區域的乾旱現象,提供台灣南部區域乾旱短期 預警及長期乾旱情況評估之參考依據。本研究所發展之乾旱機率預報模式的分析結果顯示:2001 至2009 年台灣南部區域SPI3 < 0 (偏乾)與SPI3 > 0 (偏濕)發生機率之 比例為6:4,此表示2001 至2009 年間之氣候特性偏乾;且由多模式系集機率預報 的結果顯示:以多模式系集的方法來預報可以降低單一模式機率預報的不確定性。 |
英文摘要 | Although Taiwan receives much precipitation, it is an area prone to suffer droughts due to uneven temporal distribution of precipitation and small storage capacity of reservoirs. Therefore, how to make drought early warning and protection against possible losses of life and property has been an essential issue in Taiwan. This study collected the information of Pacific large scale circulation patterns, i.e., ENSO indices, and the historical rainfall records from 7 raingauges in southern Taiwan for calculating the values of three-month standardized precipitation index (SPI3) during 1950 to 2009. Based on the theory of Markov chains, this study calculated the frequencies in the intervals among different variables (e.g., ENSO indices and SPI3) for building state transition probability matrixes to establish drought probability forecasting models. Different combinations of variables make different forecasting models. Therefore, for reducing the forecasting uncertainty of a single-model, the approach of multi-model ensemble (MME) which ensembles all single-model results was used to forecast the SPI3 probability distribution 1-month ahead by using the ENSO indices at the present time as predictors. The results show that the proposed models can well perform in providing short-term early warning of droughts in southern Taiwan and can be used to assess the long-term dry or wet conditions during a given period. For example, the ratio of the occurrence probabilities of SPI3 < 0 to SPI3 > 0 in southern Taiwan is 6:4 during 2001 to 2009, which reveals that the weather pattern was prone to dry condition during the period. |
本系統中英文摘要資訊取自各篇刊載內容。