S波段雙偏極化雷達在梅雨季豪大雨天氣系統定量降雨估計之應用

本研究利用S波段雙偏極化雷達資料，採用四種方法在臺灣西南部與北部平地和山區進行定量降雨估計實驗。選取三個梅雨季豪大雨天氣系統，時間分別為2008／6／5、2008／5／31，以及2014／5／20，前兩組為西南氣流實驗SPOL觀測個案，分別為中尺度對流系統減弱後層狀降雨以及發展成熟鋒前對流降雨天氣系統，最後一組為五分山雷達更新後觀測個案，為鋒面上線狀對流雨帶。實驗結果主要結論有：（1）山區估計降雨結果要較平地為差，相關係數較低，標準誤差較大；（2）在平地，層狀性降雨估計結果要較對流性降雨為佳；（3）QPESUMS法在平地降雨明顯高估，NEXRAD法在山區明顯低估；以及（4）Kdp法和整合法在山區降雨估計確實較NEXRAD和QPESUMS法為佳。但Kdp法在弱降雨天氣情況估計值差，尤其是使用長波長雷達（例如S波段）時，故不建議使用。本文同時說明現階段利用雙偏極化雷達進行定量降雨估計在各國使用情形，並討論遭遇的困難以及可能解決方法。

關鍵字

雙偏極化雷達；梅雨季豪雨個案；定量降雨估計；西南氣流實驗；五分山雷達

並列摘要

In this article, three Mei-Yu heavy rain events are selected for the S-band polarimetric radar-retrieved quantitative precipitation estimation (QPE) experiment, two are from SoWMEX/TiMREX NCAR SPOL radar data and the other one is from northern Taiwan Wu-Fan-San radar data. Four different radar rainfall retrieval methods are applied to these three cases. The experiment results show (1) the plain area QPE is in general much better than mountain area; (2) the stratiform rain area QPE is better than the convective rain area; (3) QPESUMS Z-R relation (R2) is overestimated over most plain area and standard NEXRAD Z-R relation (R1) is underestimated over most of the mountain area; and (4) In the mountain area, Kdp (R3) and hybrid methods (R4) performed better than the other two methods. Kdp method is too noisy for weak rain situation especially in long wavelength radars (WFS radar, for example). In the paper, we also review the current status of polarimetric radar application on QPE around the world and the difficulties they are facing and the possible solutions.

並列關鍵字

Polarimetric radar ； Heavy rain events in meiyu season ； Quantitative precipitation Estimation (QPE) ； SoWMEX/TiMREX ； SPOL ； Wu-Fan-San radar

國際替代計量

S波段雙偏極化雷達在梅雨季豪大雨天氣系統定量降雨估計之應用

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