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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/64854

    Title: 利用WRF-FSO系統探討掩星資料對颱風預報的影響
    Authors: 李念青;Lee,Nien-ching
    Contributors: 大氣物理研究所
    Keywords: 觀測影響;伴隨模式;掩星觀測;observation impact;adjoint model;GPS RO
    Date: 2014-07-30
    Issue Date: 2014-10-15 14:30:17 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 過去計算預報系統的誤差使用的是傳統觀測系統實驗的方法,近年多利用伴隨系統計算預報敏感度的方式來估計在短期預報中的觀測資料對誤差影響。本研究使用觀測資料的預報敏感度做為診斷工具來監測觀測資料在短期預報中的影響。
    伴隨模式的結果顯示,同化觀測資料對於颱風預報大部分具有正面的貢獻,在兩個颱風個案中, FORMOSAT-7/COSMIC-2表現較 FORMOSAT-3/COSMIC佳,對於擾動動能的正貢獻主要來自11000公里以上的高層。在使用完整物理參數化過程的48小時預報中,莫拉克颱風模擬結果顯示兩種掩星資料對於颱風預報並無太大分別,而在海燕颱風模擬中,FORMOSAT-7/COSMIC-2相比FORMOSAT-3/COSMIC路徑誤差可以再修正約10%左右。
    ;Observing System Simulation Experiments (OSSEs) are used to investigate current observational and data assimilation systems by testing the impact of new observations on them. Another robust tool has been developed as an adjoint-based model for assessing the impact of observations. This study use WRF-FSO system to understand their impact on short-range forecast error.
    The case chosen for the study are the typhoon Morakot (2009) and typhoon Haiyan (2013) with FORMOSAT-3/COSMIC GPS radio occultation refractivity data, simulated FORMOSAT-7/COSMIC-2 GPS RO data and GTS data. Two sets of experiments, 12-h and 24-h, have been designed to compare the RO data in vertical layers. We make a 48-h forecast for reference in addition.
    In the WRF-FSO experiment, it was found that FORMOST-7/COSMIC-2 is better than FORMOSAT-3/COSMIC data. The impact results indicate that larger impacts of GPS RO data are on upper levels for perturbation kinetic energy. In the 48-h forecast with full physics, Using FORMOST-7/COSMIC-2 RO data can improve about 10% in typhoon Haiyan track prediction than using FORMOST-3/COSMIC RO data.
    Although adjoint model can provide the Forecast sensitivity to observation at one time, but the measure still has some problem. First, it estimate the impact by simplified scheme and model. Second, we are not sure if the target zone can stand for the steering-flow region. Third, the land-sea distribution and cost function will affect the experiment result possibly. These problems increase the uncertainty of the result.
    Appears in Collections:[大氣物理研究所 ] 博碩士論文

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