台灣複雜地形氣流模式-地形阻擋效應之檢討與改進

The airflow model for complex terrain in Taiwan:analysis and improvement for the blocking effect

郭泰均(Tai-Jiun Guo)

指導教授 ： 張能復

國立臺灣大學/工學院/環境工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00878

摘要

本研究採用變分分析方法，建立台灣地區三維風場。變分分析前的客觀分析初始猜測值，嚴重的影響變分分析品質。在客觀分析內插部份，若是同時內插高空探空資料和地面離地高10m風場資料，會導致模擬結果出現紊亂且不均勻之氣流。因此，本研究先將高空部分每一層高度作探空資料時間與空間之內插，並加大濾波參數，最後才利用power law代入地面測站風場資料。如此，原本在高空上紊亂的風場被調整成較均勻且符合測站風速風向的風場。
由於台灣地形變化極大，因此氣團易受山脈屏障而影響其運動情形，而大氣穩定度是決定山脈地形如何影響氣流的行為重要條件，在大氣穩定情況下，氣流垂直位移將較小。在不穩定情況下，不穩定大氣更容易遭受山脈地形所造成的阻滯效應，會增加大氣的不穩定度與造成對流的增加。本研究將加入繞流調整模組，將客觀分析產生初始風場加以調整，以充分反應氣流繞山情形。
本研究利用Stringer理論進行繞流調整之判斷。研究結果顯示，經過了風向模組修正後，變分分析方法能充分顯現出地形效應及對近地層風場的影響。
利用上述結果之風場，本研究將針對雲嘉南地區和南高屏地區臭氧問題進行正軌跡分析，以探討是否與雲林離島工業區及高雄工業區汙染源與之相關。研究結果顯示，二維正軌跡模擬和三維正軌跡模擬類似，而三維正軌跡在離地高100m因離地面較近較易受到繞流影響。經由環保署測站資料比對結果發現，當高臭氧產生時，在雲林離島工業區軌跡皆會通過嘉義並在夜晚時風速較微弱時，滯留在嘉義地區，而造成第二天又經過光化學反應又形成高濃度臭氧。在高雄工業區方面，正軌跡會通過屏東地區，造成屏東地區臭氧高標現象，且發現夜晚會滯留於屏東地區，使得第二天經過光化學反應後臭氧又逐漸升高。由此可由正軌跡模擬結果發現與臭氧問題與工業區排放汙染源之相關性。

關鍵字

變分分析 ； 客觀分析 ； 繞流調整 ； 正軌跡

並列摘要

In this research, by using variational analysis to build three-dimensional wind field in Taiwan。Before the variational analysist, the initial guess of Objective analysis, seriously affected the quality of variational analysis. For the interpolation of Objective analysis. If interpolation surface station data and sounding station data at same time.It will show the wrong air wind speed and wind direction. This study interpolation sounding station data and Enlarges the weight values at first. Finlly , by using power law to interpolation surface station data. It can correct wind speed and wind direction.
As the Taiwan complex terrain, the wind will change flow direction from terrain.
The atmospheric stability is to determine how the terrain effects the behavior of airflow important condition. In the stability case, the airflow will be smaller vertical displacement. For the the unstable case. The airflow is easy to affected by terrain effect that will increase the instability of the atmosphere and the resulting increase convection effect.To add the wind modified module represents sufficient influence of the complex terrain area.
In this study, using Stringer theory to adjust wind direction by wind modified module . The results show that the variational analysis can fully show the topographic effect and the near surface wind field.
This study will focus on the south central region and the south area using forward trajectory to analyze the ozone problem. The results show that two-dimension and three-dimensional trajectory analyisi are similar. From EPA station data found when high ozone concentration in the Chiayi and Pingtung . The trajectory that form Yunlin industrial zone will go through Chiayi and stay in Chiayi at night when wind speed is relatively small , It is cause of the the high concentration of ozone formation by photochemical reaction on the next day. For the Kaohsiung industrial zone, The trajectory will go through the Pingtung area, resulting high ozone concentration in the Pingtung, It is will stay in the Pingtung area at night. causing the high concentration of ozone formation by photochemical reaction on the next day. From forward trajectory simulation results, show that the ozone pollution problem is related to the industrial emissions pollutant.

並列關鍵字

variational analysis ； objective analysis ； wind modified module ； forward trajectory

參考文獻

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