台灣夏季區域氣候之數值模擬

On the Simulation of the Regional Climate of Taiwan in Summer

李清縢(Ching-Teng Lee) ； 吳明進(Ming-Chin Wu) ； 陳世欽(Shyh-Chin Chen)

《環境保護》 27卷1期 (2004/06) Pp. 24-39

https://doi.org/10.30017/EP.200406.0002

摘要

本研究利用Juang and Kanamitsu (1994)和Juang et al.(1997)建立之區域波譜模式(RSM)-97v來模擬台灣夏季區域氣候之特徵。由於Chen et al.(2003)利用CCM3/RSM96v模式進行夏季及冬季各10年的台灣區域氣候模擬，結果顯示RSM模擬台灣地區的降水分佈特徵和觀測值有相當程度的一致性，但降水量卻是遠超過觀測值。推測可能是由於模式採用較簡單之雲物理過程所造成。本研究初步選定1998年5有進行模擬，探討RSM97v模式在不同雲微物理過程之下，是否會改進過大降水問題。初步結果顯示出在使用較複雜的雲微物理過程下，最大降雨區域之雨量會減少，且降水區域會有擴散之情形。此結果代表模式若使用較完整之雲微物理過程，則會改變降水分佈情形，但對於降水量卻沒有明顯的改善。
其次利用此RSM97v模式來模擬1990至2000年5至8月(MJJA)的東亞及台灣區域氣候，初步結果顯示50公里解析度之東亞區域氣候模擬結果中降水分佈特徵和NCEP再分析資料類似，但RSM更能顯示出小尺度之降水分佈特性。而RSM的模擬，在陸地上的降水量有明顯過大趨勢，但海洋上則是過少。另外在15公里解析度之台灣區域氣候模擬結果中顯示台灣地區夏季降水分佈特徵和實際觀測值有顯著誤差存在，而且降水量明顯比觀測值來得多。但從台灣全島平均降水之時間序列圖中，RSM模擬降水變化趨勢和實際觀測值類似，尤其在6月有較高的相關係數，但模擬的降水量則是過大。另外在7、8月的模擬結果中，RSM可以模擬部份因颱風所造成之台灣區域大降水現象，但對於不同颱風而言則是有高估或低估之情形，由於颱風影響台灣區域之降水原因較為複雜，所以利用此靜力平衡之區域波譜模式來模擬因颱風所造成台灣區域降水特性可能不是理想的選擇。

關鍵字

夏季區域氣候 ； 區域波譜模式

並列摘要

The National Centers for Environmental Prediction (NCEP) regional spectral Model (RSM)-97v is used to study the regional climate of Taiwan in summer. The details of this model can refer to Juang and Kanamitsu (1994) and Juang et al. (1997). Chen et al. (2003) did a 10-summer and 10-winter simulation on the regional climate with CCM3/RSM96v. It is shown that while the pattern of precipitation distribution simulated is quite close to the observation, the precipitation amount is over-estimated. It is speculated that using a simple model microphysics caused this deficit. In this study, some preliminary sensitivity tests of using more complete model microphysics to simulate the regional climate in the May of 1998 were carried out first. It is shown that less amount of the maximum precipitation did appear in the run with more complete model microphysics. However, the area of precipitation extended to the lee side of the topography. It indicates that a more complete model microphysics applied could improve the simulation on the precipitation distribution, but it could not improve on the precipitation amount.
The second, the RSM-97v with more complete microphysics setting were used to simulate the regional climate of Taiwan vicinity in the summer (May through August) of 1990-2000. It is shown that RSM tends to over predict the rainfall amount over land area while it is under-predicted over sea. Down to the local scale, the spatial distribution of the precipitation simulated is not consistent with rain-gauge observation. However, the time series of the simulated precipitation regional averaged is closely related to the observation, especially in June. The precipitation amount is significantly over-predicted. Besides, in the typhoon season, July and August, some heavy rainfall cases are missed in the simulation. RSM-97v of hydrostatic version could be not good for regional climate simulation while involved typhoon.

並列關鍵字

Regional climate in summer ； Regional spectral model