The influence of tropical cyclone Melor on PM10 concentrations during an aerosol episode over the Pearl River Delta region of China: Numerical modeling versus observational analysis
The influence of tropical cyclone Melor on PM10 concentrations during an aerosol episode over the Pearl River Delta region of China: Numerical modeling versus observational analysis
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DOI：
10.1016/j.atmosenv.2007.01.055
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发表时间：
2007-07
影响因子：
5
通讯作者：
Yerong Feng;Anyu Wang;Dui Wu;Xiangde Xu
中科院分区：
文献类型：
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作者：
Yerong Feng;Anyu Wang;Dui Wu;Xiangde Xu
本文对2003年11月1-3日发生在珠江三角洲地区的一次气溶胶事件进行了数值模拟和观测分析。采用中尺度模式MM 5、化学输送模式MODELS-3/CMAQ和大气污染物排放模式SMOKE组成的大气质量模式系统。研究表明，这次颗粒物（PM）污染事件显然与热带气旋（TC）Melor的活动有关。模型模拟表明，Melor通过动力学和热力学过程产生了这一PM事件。梅洛外围环流引起的强烈补偿性沉降创造了有利的气象条件，增强了当地的气溶胶污染。这种强烈的向下运动导致珠江三角洲上空的低层对流层显著绝热变暖（每天2-4°C）和急剧干燥。结果，珠三角地区被干燥和温暖的空气层覆盖，加强了对流层低层的静力稳定性。下降运动也倾向于通过其动力效应显著降低行星边界层（PBL）的高度。这种天气模式所造成的晴朗天气通过增强辐射冷却进一步加强了夜间逆温。所有这些因素促使当地大气停滞，表面附近有非常微弱的风。本地排放的气溶胶粒子的水平和垂直扩散在很大程度上受到抑制，导致大量PM在珠三角地区本地排放源附近积聚。当梅洛接近时，地面风的变化加强了气溶胶粒子从内陆来源到香港下游地区的水平输送。这种水平平流对香港高浓度的PM10（直径小于10微米的颗粒物）有很大的影响。
In this article, numerical simulations and observational analyses have been made for the aerosol episode that occurred over the Pearl River Delta (PRD) region in China during 1–3 November 2003. An air quality modeling system that consisted of the mesoscale model MM5, chemical transport model MODELS-3/CMAQ, and air pollutant emission model SMOKE, was employed. Studies have shown that this particulate matter (PM) pollution episode was apparently associated with the activity of tropical cyclone (TC) Melor. Model simulations revealed that Melor spawned this PM episode through dynamic and thermodynamic processes. The strong compensating subsidence induced by Melor's peripheral circulations created favorable meteorological conditions that enhanced local aerosol pollution. This strong downward motion produced significant adiabatic warming (2–4°C daily) and dramatic drying in the low-level troposphere over the PRD. As a result, the PRD region was blanketed with a dry and warm air layer that strengthened the static stability of the lower troposphere. The descending motion also tended to dramatically lower the heights of the planetary boundary layer (PBL) through its dynamic effect. The fair weather created by this synoptic pattern further intensified the nocturnal temperature inversions through enhanced radiative cooling. All of these factors promoted a stagnant local atmosphere with very light winds near the surface. The horizontal and vertical dispersions of locally emitted aerosol particles were largely suppressed, leading to the accumulation of large amounts of PMs near local emission sources in the PRD region. As Melor drew near, changes in surface winds strengthened the horizontal transport of aerosol particles from inland sources to the area of Hong Kong downstream. This horizontal advection greatly contributed to the high PM10(particulate matters less than 10μm in diameters) concentrations in Hong Kong.