Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China
Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China
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DOI：
10.5194/acp-11-12421-2011
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发表时间：
2011-12
影响因子：
6.3
通讯作者：
Yuan Wang;Q. Wan;W. Meng;F. Liao;H. Tan;Renyi Zhang
中科院分区：
文献类型：
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作者：
Yuan Wang;Q. Wan;W. Meng;F. Liao;H. Tan;Renyi Zhang
抽象的。利用2000 - 2006年珠江三角洲地区（以广州市为重点）7年的降水、闪电和能见度资料，分析了珠江三角洲地区降水、闪电和能见度的变化特征。统计分析表明，暴雨（>25 mm/d）和雷击频率与能见度呈显著正相关。为了阐明气溶胶对云过程、降水和闪电活动的影响，利用一个云分辨天气研究与预报模式（CR-WRF）和一个二阶矩体微物理方案，对2009年3月28日发生在广州地区的一次中尺度对流系统进行了数值模拟。模式预报的合成雷达反射率和累积降水量的演变与S波段天气雷达和自动站的观测结果基本一致。计算的雷电潜势指数（LPI）与当地闪电监测网记录的闪电在时间和空间上具有一致性。敏感性实验已经进行，以反映气溶胶条件的污染和清洁的情况下的代表。模拟结果表明，在污染气溶胶条件下，降水和LPI分别增加约16%和50%。我们的研究结果表明，气溶胶负荷升高抑制轻，中度降水（每天小于25毫米），但增强强降水。水凝物和潜热释放对不同气溶胶负荷的响应揭示了广州特大城市降水和闪电增强的物理机制，即在污染气溶胶条件下，混合相过程更有效，对流增强。
Abstract. Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD) region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day) and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving – Weather Research and Forecasting (CR-WRF) model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI) exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16% and 50%, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day), but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.