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標題: | 快速增強與緩慢增強颱風雲微物理與降雨類型之比較研究 A Comparison Study of Rainfall Regimes and Microphysics Characteristics between Rapidly-Intensifying and Slow-intensifying Tropical Cyclones |
作者: | 黃詣軒 Yi-Hsuan Huang |
指導教授: | 楊明仁 Ming-Jen Yang |
關鍵字: | 快速增強,緩慢增強,冰水路徑,雨水路徑,降雨類型, Rapid Intensification (RI),Slow Intensification (SI),Ice Water Path (IWP),Rain Water Path (RWP),rainfall regimes, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 我們對於快速增強(Rapid Intensification;RI)和緩慢增強(Slow Intensification;SI)颱風之間的降雨類型和雲微物理特徵的差異與演變目前的認知有限。為討論此議題,我們不僅分析了SSMIS (Special Sensor Microwave Imager/Sounder)儀器反演的冰水路徑(Ice Water Path;IWP)和雨水路徑(Rain Water Path;RWP)及紅外頻道的亮溫(Brightness Temperature),還進行了WRF(Weather Research and Forecasting)模式模擬,以討論RI和SI的颱風之間降雨類型和雲微物理特徵的差異與演變。此外,我們分別針對RI和SI個案使用WRF模式進行暖雲和冷雲微物理方案的影響敏感度測試。
從SSMIS觀測中,我們發現在2倍最大風速半徑(RMW)以內,RI颱風的IWP和RWP的量值在增強開始前12小時之後大於SI颱風的量值。且在增強開始前12小時和增強開始後的12及24小時,IWP和RWP在2倍RMW內,95%的信心水準下RI颱風顯著多於SI颱風的量值。而紅外頻道的亮溫則指出:在增強前12小時的時候,颱風3RMW內的區域RI颱風個案的亮溫低於SI的颱風個案,並於增強開始後2RMW內多數區域紅外的亮溫於95%的信心水準下RI颱風顯著低於SI颱風的量值,尤其是在上風切處格外顯著。 不論是在SSMIS觀測或WRF模擬結果,我們發現颱風增強開始前IWP和RWP在下風切處量值大於上風切處,其中又以Downshear Left (DL)象限的量值最大。 RI開始後,Upshear Left (UL)象限中的IWP和RWP逐漸增大,但是SI的颱風並沒有出現類似的演變。同時我們亦發現RI颱風個案在其RI正要開始前,IWP與RWP及對流有發生快速減弱的情形。 在WRF控制組模擬RI和SI 個案降水類型的差異比較中,我們發現進行分析的大多數時段中,RI 颱風個案中DL和UL象限的深對流(DC)和中等對流(MC)的比率大於SI 颱風個案的比率。同時資料顯示,不論RI或SI的颱風個案其上風切處的層狀降水(ST)面積,均在增強(RI/SI)開始的前後有逐漸增加的情形。 在暖雲敏感度模擬實驗中,我們發現RI颱風個案其RI開始的時間明顯提前,而SI颱風個案則沒有發生類似現象。暖雲實驗指出,RI和SI的個案在增強(RI/SI)開始後其對流強度均不及控制組的對流強度,且暖雲實驗中ST和WE的面積高於控制組的面積,此情形在颱風的上風切處格外顯著。 The differences and evolution of rainfall regimes and microphysics characteristics between rapidly-intensifying (RI) and slowly-intensifying (SI) tropical cyclones (TCs) are not well discussed understood. Owing to this predicament, we analyzed the ice water path (IWP) and rain water path (RWP) retrieved from the Special Sensor Microwave Imager/Sounder (SSMIS), brightness temperaute from infrared channel, and conducted the Weather Research and Forecasting model (WRF) simulations to examine the differences and evolution of rainfall regimes and microphysics characteristics between RI and SI TCs. To clarify the influences by warm-rain and cold-rain microphysics schemes, we also conducted sensitivity tests with the WRF model on RI and SI cases, respectively. From the SSMIS observations, we found that the IWP and RWP in RI TCs were greater than those in SI TCs within twice the radius of maximum wind speed (RMW) 12 hours before the intensification onset. The differences in IWP and RWP between RI and SI TCs within the RMW were significant at the 95% confidence level at the intensification onset and within twice the RMW at 12 hours before, 12 hours after, and 24 hours after the intensification onset. The brightness temperature analysis of infrared channel indicated that, at 12 hours before intensification onset, the brightness temperature of the RI cases was lower than that of the SI cases within 3RMW. After the onset of intensification, the RI cases exhibited significantly lower infrared brightness temperatures compared to the SI cases at the 95% confidence level within most of the area of 2RMW. This difference was particularly prominent in the upshear quadrant. Both the SSMIS observations and WRF simulations showed that the IWP and RWP were generally larger in the downshear flank before the intensification onset, especially in the downshear left (DL) quadrant. The IWP and RWP in upshear left (UL) quadrant gradually became larger after the RI onset, yet similar evolution did not occur in SI TCs. The IWP and RWP were quickly weakened just before the RI onset in RI TCs. We also compared the differences of precipitation regimes between RI and SI TCs. We found that the ratios of deep convection (DC) and moderate convection (MC) at DL and UL quadrants in RI TCs were greater than those in SI TCs for most periods we analyzed. The ratios of stratiform precipitation (ST) at UL and upshear right (UR) quadrants gradually increased after the RI and SI onset when we analyzed precipitation type including non-precipitating grids. From the warm-rain sensitivity tests, we found that the timing of the RI onset significantly occurred earlier while the same consequence did not occur in SI case. We not only demonstrated that the precipitation intensity and convection were weaker in both RI and SI case after intensification began, but also found that the ratios of ST and WE were greater in warm rain experiment than those in control runs in precipitation type analysis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88138 |
DOI: | 10.6342/NTU202301514 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 大氣科學系 |
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