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研究生:尤心瑜
研究生(外文):Hsin-yu Yu
論文名稱:同化都卜勒雷達資料改善模式預報之研究
指導教授:廖宇慶
指導教授(外文):Yu-Chieng Liou
學位類別:碩士
校院名稱:國立中央大學
系所名稱:大氣物理研究所
學門:自然科學學門
學類:大氣科學學類
論文種類:學術論文
論文出版年:2009
畢業學年度:97
語文別:中文
論文頁數:93
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本研究目的為探討:同化都卜勒雷逹資料及其所反演的大氣狀態變數,於改善劇烈風暴發展預報的可行性。而此研究方法的流程共包含以下三部份:雙都卜勒雷達風場反演、熱動力反演及水汽調整。
研究共設計6組實驗,而所有的實驗都是在 OSSE實驗架構下進行,其測試內容如下:(a)研究方法完整流程的測試、(b)同化次數及同化時間間距的測試、(c)探討探空資料在同化過程中所扮演的角色、(d)測試同化都卜勒雷逹資料及反演氣壓場,並於同化過程中利用垂直動量方程式來得到溫度場,看其對模擬結果的影響。
實驗結果顯示,經同化都卜勒雷逹觀測資料及其反演的大氣狀態變數後,的確改善初始條件微弱風暴的降水預報結果。於同化次數及同化時間間距的測試,則發現兩者對於改善預報降水的敏感度較低;而在同化過程中,給予探空資料將提升同化結果的準確度,並在此同化之後,再進行一次沒有探空資料的同化,於預報結果有更進一步的改善。而未來最重要的工作目標,則是將本研究方法,應用在真實個案上,期望在實際作業上能改善定量降水的預報能力。
The purpose of this study is to explore the feasibility of assimilating atmospheric state variables observed as well as derived from Doppler radar data to improve the prediction of a thunderstorm development. In the methodology, the complete algorithm is composed of three steps, namely (1) wind retrieval, (2) thermodynamic retrieval, and (3) moisture adjustment. The performance of the proposed method is investigated by six experiments, and all of them are conducted under the framework of OSSE (Observation System Simulation Experiment). From these experiments, it is attempted to address the following issues: (1) verification of proposed method (2) the impact of the assimilation frequency and assimilation time interval, (3) influence of assimilating with/without sounding data, and (4) influence of assimilating Doppler radar data and retrieval pressure field only. In (4), the vertical momentum equation is utilized to obtain the absolute potential temperature fields.
The results demonstrate that the accuracy of storm rainfall prediction can be improved after assimilating observed/retrieved atmosphere state variables from Doppler radar data. However, the impact on rainfall prediction from the assimilation frequency and time interval is insignificant. By contrast, the model forecast can be improved substantially if the data from a sounding released within the analysis domain is available. Furthermore, after the first assimilation with sounding, if one conducts a second assimilation even without the information from sounding observations, additional improvements can be achieved. The application of this method to real case study would be a natural extension of this study in the future.
中文摘要……………………………………………………………… i
英文摘要………………………………………………………………ii
誌謝 ………………………………………………………………iii
目錄 ………………………………………………………………iv
圖表目錄 …………………………………………………………vi

第一章 前言………………………………………………… …1
1.1 研究動機 …………………………………………………1
1.2 文獻回顧 …………………………………………………2
1.3 論文架構 …………………………………………………4
第二章 研究方法 ………………………………………………5
2.1 都卜勒雷達風場合成 …………………………………5
2.2 熱動力反演方法…………………………………………7
2.3熱動力場及水汽調整方法…………………………… 10
第三章 實驗設計 ……………………………………………14
3.1 數值模式介紹 …………………………………………14
3.1.1 WRF 模式設定 …………………………………… 14
3.1.2 OSSE 實驗概念…………………………………… 15
3.2 實驗流程介紹 ………………………………………16
3.3 檢驗方法 …………………………………………………17
3.3.1 同化結果檢驗方法 ……………………………… 18
3.3.2 定量降水檢驗方法 ……………………………… 19
第四章 結果分析 …………………………………………21
4.1 實驗1:『研究方法測試一』 ………………………21
4.2 實驗2:『研究方法測試二』 ………………………23
4.3 實驗3:『同化次數測試』 ………………………25
4.4 實驗4:『同化時間間距測試』………………………28
4.5 實驗5:『探空資料的影響』 ………………………30
4.6 實驗6:『使用垂直動量方程式計算溫度場測試』
……………………………………………32
第五章 結論與未來展望…………………………………… 35
5.1 結論 ………………………………………………35
5.2 未來展望 ………………………………………………36
參考文獻 ………………………………………………………… 38
附表與附圖 ………………………………………………………… 42
略語表 ………………………………………………………… 79
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