An Operational Quadtree-Adaptive Model to Predict the Wave Fields Generated by Typhoons

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Project title

Code/計畫編號

MOST103-2221-E022-017-MY2

Translated Name/計畫中文名

以作業化自調適四元樹模式預測颱風波浪場

Project Coordinator/計畫主持人

Chia-Cheng Tsai

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Marine Environmental Engineering,NKUST

Website

https://www.grb.gov.tw/search/planDetail?id=11274153

Year

2015

Start date/計畫起

01-08-2015

Expected Completion/計畫迄

31-07-2016

Bugetid/研究經費

480千元

ResearchField/研究領域

土木水利工程
防災工程

近來全球氣候快速變遷，大氣與地殼活動日益頻繁劇烈，熱帶氣旋與海嘯等毀滅性災難層出不窮，全世界已開始正視此棘手問題而展開大規模的研究並採取相關因應之道。此時台灣面對國土保育、海岸防護機制與對策已是刻不容緩。全域性風波浪場之預測與準確性一直都是科學家研究海洋波動之最大目的，不僅防災預警，更有助於海洋能源開發與利用。但是就數值計算上，大規模平面的模擬仍是會受數值方法與計算機的處理極限所限制，例如格網粗細取決，不規則邊界格網最佳分佈等等。而這些因素也會成為影響精度的問題所在。所以數值技術上更新並搭配調適性之計算格網，對於現階段台灣預警防災之應用上才能達到最有效率的提升。本研究計畫乃是擴展自調適四元或八元樹狀網格系統求解波浪作用力平衡方程式(wave action balance equation)之全域性問題，藉由網格自動調適性隨著風場隨時間變動而改變。而且在全域性之精度與計算時間考量下，此法可有效控管所需之網格總數，不會如同傳統數值格網分佈而增加需多無謂之計算。最後，將此模式與台灣周遭海域之風場資料做系統性的結合，調整出最合適之各項參數，以其對太平洋生成之颱風湧浪之波譜預測提供最佳以及最有效率之預測與後續資料比對分析。進一步，我們將調整模式源項，使其能自動根據水深，調整為 WAVEWATCH 或 SWAN，這樣，當我們將建立作業化風波浪系統，模式將包含自調適功能(跟著颱風動或跟著感興趣的商船動)，應用於台灣周邊海域。 Recently, the global climate has been changed rapidly than expected. Activities of atmosphere and crust are increasing frequently. All over the world, governments have now started to concern this issue seriously and find sustainable solutions. People who lived in Taiwan also have to face the same impact of reality. The main purpose of most marine physicist is how to predict the global wind wave field precisely. However, there are some limits of numerical process such like the distribution of grids. Therefore, the adaptive technique has been a new tendency for coastal application and protection. As a result, we need to develop these kinds of new technology as early as possible for disaster prevention in Taiwan and we can raise the response ability directly as well. In this project, we are going to use a quadtree-adaptive grid system to solve the wave action balance equation for global wind wave problems. Distribution of the grid changes with the movement of the wind field. This can provide us a more efficient simulation. In the mean time, lower resolutions do not cause a distortion of results as well. In addition, we are going to combine this model and wind field data around Taiwan systematically. Also, we will try to search the best adaptive parameters in the model in the future. And then we believe it will provide a great contribution for a prediction of the wave spectrum. In the last, we will implement the model such that it can switch the source term to either the WAVEWATCH or the SWAN according to the water depth. Finally, we will establish an operational wind-wave modelling system. This model can be adaptive to the typhoons and/or concerned vessels and will be applied to the ocean around Taiwan.

Keyword(s)

颱風
風波浪場
自調適四元樹網格
浪作用力平衡方程式
typhoon
wind wave field
adaptive quadtree grid system
wave action balance equation

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An Operational Quadtree-Adaptive Model to Predict the Wave Fields Generated by Typhoons

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