English  |  正體中文  |  简体中文  |  Items with full text/Total items : 66984/66984 (100%)
Visitors : 23024690      Online Users : 211
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version


    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/25604


    Title: 台灣大氣研究計畫(III)---西南氣流觀測與豪雨預報實驗暨後續研究---偏極化雷達參數變分方法研究及西南氣流實驗個案應用;The Variational Method for Polarimetric Variables and Its Applications in Sowfex/Timrex (III)
    Authors: 陳台琦;廖宇慶
    Contributors: 大氣科學系
    Keywords: 大氣科學類
    Date: 2010-07-01
    Issue Date: 2010-06-10 17:31:43 (UTC+8)
    Publisher: 行政院國家科學委員會
    Abstract: 雲微物理的發展過程及其各種降水粒子之總量對於分析及了解各類劇烈天氣系統有相當大的幫助。透過了解各類雲微物理過程及降水粒子總量在三維空間上的分布,不僅對於暸解系統發展上有相當大的助益,能提供數值天氣預報模式更佳的雲微物理初始分佈場,進而提高劇烈天氣預報的準確性。近年來,在氣象雷達遙測技術方面上有相當大的進步,雙偏極化氣象雷達利用其同時發射垂直及水平電磁波的特性,藉由多觀測參數提高其在雲微物理場的辨識度,降水粒子的大小、形狀、掉落特性及相位(水象或冰象),皆可藉由雙偏極化雷達的多觀測參數來進行分析及了解。台灣第一座C波段(5公分)雙偏極化氣象雷達,由中央大學、大氣物理研究所、雷達氣象研究室於2004 年12 月換裝升級完成,並成功的運轉,提供台灣北部地區雙偏極化觀測達已4年有餘。在2008年5月,西南氣流實驗SOWMEX/TIMREX (Terrain- Influenced MonsoonRainfall Experiment)此國際聯合觀測實驗於南台灣地區進行。台灣國科會及中央大學大氣物理研究所雷達氣象實驗室共同建置的TEAM-R(台灣第一部移動式氣象雷達-X波段(3公分)雙偏極化雷達),同時參與此一實驗,此實驗將提供最佳的機會,進行S-Pol及TEAM-R同步觀測,收集到S及X波段的雙偏極化觀測參數對同一天氣系統資料,此資料可做為進行X波段衰減修正方法建立之最佳對照資料庫,並可進一步分析不同波段之雙偏極化觀測參數在不同降水粒子中的傳播特性。由於C波段及X波段雙偏極化雷達都會受到降水粒子造成的衰減,導致回波強度及差異反射率須透過差異相位差修正。本計畫將採用一個新的變分方法,利用三個約束條件修正回波強度及差異反射率,計畫將先採取觀測系統模擬實驗(OSSE)以5年的雨滴譜儀資料,透過散射模擬產生包括了衰減效應後之偏極化雷達參數,再透過變分反演,第二步驟則將進行包括觀測誤差的測試,最後階段將以TEAM-R真實資料進行反演,並與無衰減的S-Pol資料比對。此方法可突破現在一般使用的單係數及最佳係數修正方法的缺點,得到一組符合散射原理的最佳資料。並且可以做為未來偏極化雷達資料同化的基礎。 In year 2008, the TEAM-R (Taiwan Experimental Atmospheric Research-Radar) X-band polarimetric radar successfully collected the meteorological data. However, the X-band radar is suffered by the attenuation effect. Currently, the single coefficient attenuation correction method and the optimal attenuation correction method are most adopted by many polarimentric radar analyses. The both methods have advantage and disadvantage, for example, the optimum adjustment method occasionally encounter difficulty in multiple rain bands or complicate meso-convective systems. In this research, the polarimetric measurements of differential reflectivity (Zdr) and differential phase (Φdp) were considered as the predicted measurements and the intercept coefficient (a) of the relation between reflectivity (Zhh) and rainfall rate (R) was considered as the target variable. The main purpose of this research was to evaluate the variational algorithm to the Zhh and Zdr attenuation of a X-band polarimetric radar via OSSE test and a real case study. The cost-function contained three constraints in this variational algorithm. These three constraints are the Zdr and ΦDP from the polarimetric radar measurements and the background term which was the function of Zdr andΦDP. The final results can provide a set of adjusted Zhh and Zdr with consistent attenuation correction through variation method. The real case test will further enhance the accuracy of the TEAM-R quality control data set.研究期間 : 9808 ~ 9907
    Relation: 財團法人國家實驗研究院科技政策研究與資訊中心
    Appears in Collections:[大氣科學學系] 研究計畫

    Files in This Item:

    File Description SizeFormat
    index.html0KbHTML427View/Open


    All items in NCUIR are protected by copyright, with all rights reserved.

    社群 sharing

    ::: Copyright National Central University. | 國立中央大學圖書館版權所有 | 收藏本站 | 設為首頁 | 最佳瀏覽畫面: 1024*768 | 建站日期:8-24-2009 :::
    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback  - 隱私權政策聲明