Observational evidence of aerosol enhancement of lightning activity and convective invigoration
Observational evidence of aerosol enhancement of lightning activity and convective invigoration
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DOI：
10.1029/2010gl046052
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发表时间：
2011-02
影响因子：
5.2
通讯作者：
T. Yuan;L. Remer;K. Pickering;Hongbin Yu
中科院分区：
文献类型：
--
作者：
T. Yuan;L. Remer;K. Pickering;Hongbin Yu
菲律宾以东西太平洋上的闪电活动通常比附近海洋大陆上的闪电活动要少得多。然而，2005年，TRMM卫星上的闪电成像传感器(LIS)在该地区观测到异常高的闪电活动。同年，中分辨率成像光谱仪(MODIS)测量到异常高的气溶胶负荷。高气溶胶含量可追溯到火山活动，而不是与气象学有关的任何因素，解开了气溶胶和气象学之间通常的旋涡。我们发现，在年际和每两周的时间尺度上，闪电活动与气溶胶负荷都是密切相关的。我们估计，∼浓度每增加60%，闪电次数就会增加150%以上。气溶胶通过修改云微物理来增加闪电活动。随着气溶胶含量的增加，云冰颗粒尺寸减小，云冰川延迟到较低温度。TRMM降水雷达测量表明，异常高的气溶胶负荷与海洋上空云混合相活动增强和对流增强有关。这些观察到的气溶胶、云微物理、形态和闪电活动之间的联系与气象变量或ENSO事件无关。这些结果对于理解闪电的可变性和由此产生的气溶胶-化学相互作用具有重要的意义。
Lightning activity over the West Pacific Ocean east of the Philippines is usually much less frequent than over the nearby maritime continents. However, in 2005 the Lightning Imaging Sensor (LIS) aboard the TRMM satellite observed anomalously high lightning activity in that area. In the same year the Moderate resolution Imaging Spectroradiometer (MODIS) measured anomalously high aerosol loading. The high aerosol loading was traced to volcanic activity, and not to any factor linked to meteorology, disentangling the usual convolution between aerosols and meteorology. We show that in general lightning activity is tightly correlated with aerosol loadings at both inter‐annual and bi‐weekly time scales. We estimate that a ∼60% increase in aerosol loading leads to more than 150% increase in lightning flashes. Aerosols increase lightning activity through modification of cloud microphysics. Cloud ice particle sizes are reduced and cloud glaciation is delayed to colder temperature when aerosol loading is increased. TRMM precipitation radar measurements indicate that anomalously high aerosol loading is associated with enhanced cloud mixed phase activity and invigorated convection over the maritime ocean. These observed associations between aerosols, cloud microphysics, morphology and lightning activity are not related to meteorological variables or ENSO events. The results have important implications for understanding the variability of lightning and resulting aerosol‐chemistry interactions.