臺灣北部放射性污染物擴散之數值模擬：冬季個案研究
Other Title
Numerical Simulation of Radioactive Pollutant Dispersion over Northern Taiwan: A Winter Case Study
Journal
臺灣地區空氣污染與農業氣象對作物生產影響研討會專輯
Pages
276-287
ISBN
957-97038-4-1
Date Issued
1993-04
Date
1993-04
Author(s)
黃清勇
Ching-Yuang Huang
Abstract
本文探討盛行東北季風以及台灣北部複雜地形條件下近地污染面源的擴散過程。文中使用一中尺度數值模式來作數值模擬。此模式包含邊界層高階參數化、雲物理以及污染物濃度預報方程。模式模擬結果顯示，若污染源為大屯山脈迎風面核一、二廠走之面源，中尺度局部地形環流的平流及擴散過程不可避免地將輻射性污染物帶入大台北盆地。核一廠的污染物可經由淡水河谷及基隆河谷，而核二廠污染物主要是由基隆河谷，進入了大台北盆地。在強盛行風下，兩廠之污染物均越過林口台地並於三、四小時內影響桃園及新竹地區，平均地面濃度值則降為約原污染源濃度的十分之一。若考慮白日地面加溫作用，則因大氣邊界層迅速發展，盆地濃度可再被稀釋成百分之一。但在弱風且近地熱力穩定情況下，大台北盆地的最大濃度值可為污染源濃度一半以上。在東北季風情況下，核四廠對宜蘭地區則有較大的影響。本文個案模擬結果顯示，福祿數(Froude number)不失為了解北台灣山嶽氣流特徵（過山、繞山及偏射）之有用參數，水平平流作用亦大致決定污染物移動與幾何分佈情況，然而近地大氣亂流的垂直擴散作用實為決定地面濃度大小更重要的因子。
This study investigated diffusion processes of near-surface area pollutant sources over complex terrain of northern Taiwan under prevailing northeast monsoon. Numerical simulations were performed by a mesoscale numerical model which includes a high-order closure scheme of planetary boundary layer parameterization, cloud microphysics and the prognostic equation for pollutant concentration. Model simulation results showed that for area sources over the upstream side of Da-Tun Mountain Range, radioactive pollutants were inevitably taken into the metropolitan Taipei Basin thru advection and diffusion processes of local topographically-induced mesoscale circulations. Pollutants from Station I of nuclear energy plants can be brought into Taipei Basin thru Tan-Shul River and Kee-Long River, while pollutants from Station 2 entered mainly thru Kee-Long River. For stronger prevailing winds, pollutants from both stations can be flowed over Lin-Kou Table land and contaminate Tao-Yuan and ilsin-Chu by 3-4 hours with the ground-level pollutant concentration about one-tenth of the original source concentration. With the diurnal surface heating included, the concentration can be further reduced to about one-hundredth. The maximum concentration over Taipei Basin could retain more than one-half of the source intensity for weaker winds under stable conditions. For the prevailing northeast monsoon, I-Lan area was more affected by Station 4. The winter case results indicated that Froude number appears to be an effective parmeter for an understanding of the mountain flow behaviors (passing over, surrounding or deflecting) in northern Taiwan. Horizontal advection processes mostly controlled the pathways and geometric distributions of the pollutants, while vertical diffusion processes of the atmospheric turbulence near the surface was a more dominant factor for the deter mination of concentration magnitude.
Event(s)
臺灣地區空氣污染與農業氣象對作物生產影響研討會
Proceedings of The Workshop on Effects of Air Pollution and Agrometeorology on Crop Production in Taiwan
Subjects
中尺度數值模式
污染物
大氣亂流
Mesoscale numerical model
pollutants
atmospheric turbulence
Publisher
行政院環境保護署、行政院農業委員會、臺灣省政府農林廳
Type
conference paper
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