亞洲沙塵暴之模擬

A Modeling Study of the Long-range Transport of Asian Dust

吳承翰(Chen-Heng Wu) ； 彭啟明(Chi-Ming Peng) ； 林能暉(Neng-Huei Lin)

《環境保護》 28卷2期 (2005/12) Pp. 202-220

https://doi.org/10.30017/EP.200512.0007

摘要

本研究旨在應用大氣傳送模式模擬亞洲沙塵在大氣中的傳送擴散與分布情形，進而量化其對對台灣空氣品質之影響程度。分析2000-2001年之沙塵暴個案，高低壓間的強風速帶移入中國西北或華北之沙漠區，是造成沙塵暴現象產生的原因之一，由500hPa天氣圖分析結果可發現斜壓的情形會使得沙源風速更強，溼度更低，進而發生揚塵或沙塵暴之天氣現象。在影響台灣的個案中，沙塵主要受到高壓牽引的影響而往東南方之下游處移動，從產生到影響台灣的時間在36-96小時之內，端視天氣系統移動速度而定。
經由氣流軌跡後推結果可發現個案期間之氣流皆來自於中國西北或華北一帶，顯示台灣空氣品質惡化主因在於沙塵暴的影響。經由大氣傳送模式模擬沙塵暴傳送過程之結果發現沙塵行進方向受高壓行進路線影響而先往東南方移動，當移出中國時會受日本附近之低壓牽引而往東北方向移動。定性上，模式掌握度佳；定量上，與觀測資料比較時，各個案表現不一，不確定性應包括氣象場解析度、沙塵源區之土壤成份以及大氣中之沙塵與氣膠的交互作用等。

關鍵字

亞洲沙塵 ； 大氣傳送 ； 空氣品質

並列摘要

The purpose of this study is to apply atmospheric transport model to simulate the transport, dispersion and distribution of Asian dusts, and further to assess their impact on the air quality of Taiwan. During the dust storm cases in 2000-2001, the occurrence of strong gradients of surface winds which are between High and Low moving toward to the northwestern and the northern China is one of the major reasons to initiate them. Moreover, the atmospheric baroclinicity enhanced the wind fields and lowered humidity, inducing the dust lifting. Amongst those dust cases affecting Taiwan, anticyclonic outflows forced the dusts moving southeastwards and arriving in 36-96 hours, depending on the movement of the weather system.
Through the trajectory analysis, it can be found that for the dust storm cases affecting Taiwan's air quality, the air flows were all originated from the northwestern and northern China. Qualitatively, our model can capture the major features of dust transport. However, quantitative estimates exhibited inconsistency with observations for some stations. The uncertainties in model simulations can be attributed to meteorological resolution, soil properties of source regions and the interaction between dust and aerosol particles.

並列關鍵字

Asian dust ； atmospheric transport ； air quality