季風槽及熱帶氣旋活動模擬於WRF 30公里解析度區域氣候模式
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2011
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西北太平洋是熱帶氣旋活躍的地區，熱帶氣旋摸擬及研究是重要熱門的議題。然而早期模擬以低解析度全球模式為主要工具，模擬出來之熱帶氣旋有暖心結構及環流系統，但中心強度不太理想。故本研究考慮了海陸分佈和地形以及中、東太平洋、印度洋之影響，採用Weather Research and Forecasting (WRF)
30公里之解析度，針對2000~2009年間之夏、秋兩季進行區域氣候模擬，並設計了NWP(100°E~180°,5°S~35°N)、NP(100°E~120°W,10°S~40°N)、IONWP (50°E~180°,20°S~40°N)三組不同範圍之實驗，來探討西北太平洋地區位於東亞季風區，而東亞季風、太平洋副熱帶高壓及太平洋海溫分佈是影響熱帶氣旋生成及活動之因素。並偏重在秋季大尺度環流及熱帶氣旋的探討。
在NCEP觀測資可發現，大尺度環流影響了熱帶氣旋之生成及軌跡。而在模式中均有掌握大尺度環流及熱帶氣旋活動之關係。但在NWP及NP模擬季風槽有過強之現象，而使副高位置東移。使秋季熱帶氣旋生成數量、位置及軌跡較不完全符合JTWC資料。然而IONWP則在季槽風模擬中要接近於觀測，在大尺度環流掌握度較佳。在秋季熱帶氣旋之模擬中生成數量、位置及軌跡均模擬良好。模式在提高解析度之下，三組模式均有達到一定的強度，但仍稍弱於JTWC資料。可見模擬過程加入印度洋、南亞陸塊及青康藏高原，模式有掌握大尺度環流之特徵，並影響及掌握秋季熱帶氣旋之活動。
Monsoon trough is one of the major factors that influence the climate and typhoon activities in the west North Pacific Ocean. However, the structure of monsoon trough and tropical storms are often poorly simulated by the Global Climate Models (GCMs) due to their coarse resolutions. In this study, Weather Research and Forecasting (WRF) Regional Climate Model (RCM) at 30-km resolution is adopted to simulate the climatological feature of monsoon trough and tropical storms from 2000 to 2009. Numerical experiments with three different domains including NWP (105°E-180°, 0°-40°N), NP(105°E-120°W, 5°S-45°N), and IONWP (45°E-180°, 20°S-40°N) are conducted to investigate the relative contributions from tropical East Pacific Ocean, Indian Ocean and land-sea contrast to the monsoon trough. The results show that the gross features of large-scale circulations are well captured by all three experiments. Nevertheless, monsoon troughs are too strong, while subtropical highs are too weak in NWP and NP experiments. This causes the low-level convergence region simulated in NWP and NP experiments to the east of the observation. With the inclusion of Indian Ocean and land-sea contrast, the strength of monsoon trough, subtropical high, and low-level convergence are well represented in IONWP experiment. These large-scale circulations are closely related to the typhoon activities in all three experiments.
Monsoon trough is one of the major factors that influence the climate and typhoon activities in the west North Pacific Ocean. However, the structure of monsoon trough and tropical storms are often poorly simulated by the Global Climate Models (GCMs) due to their coarse resolutions. In this study, Weather Research and Forecasting (WRF) Regional Climate Model (RCM) at 30-km resolution is adopted to simulate the climatological feature of monsoon trough and tropical storms from 2000 to 2009. Numerical experiments with three different domains including NWP (105°E-180°, 0°-40°N), NP(105°E-120°W, 5°S-45°N), and IONWP (45°E-180°, 20°S-40°N) are conducted to investigate the relative contributions from tropical East Pacific Ocean, Indian Ocean and land-sea contrast to the monsoon trough. The results show that the gross features of large-scale circulations are well captured by all three experiments. Nevertheless, monsoon troughs are too strong, while subtropical highs are too weak in NWP and NP experiments. This causes the low-level convergence region simulated in NWP and NP experiments to the east of the observation. With the inclusion of Indian Ocean and land-sea contrast, the strength of monsoon trough, subtropical high, and low-level convergence are well represented in IONWP experiment. These large-scale circulations are closely related to the typhoon activities in all three experiments.
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區域氣候模式, 季風槽, 熱帶氣旋, regional climate model, monsoon trough, tropical cyclone