利用2005年11月至2006年2月ACTIVE(Aerosol and Chemical Transport in tropIcal con VEction)外场试验期间在澳大利亚北部达尔文地区取得的CO、O3、NO和NOx飞机探测资料,并结合HYSPLIT后向轨迹模式结果,分析这几种气体成分在对流卷云砧内外的分布情况,并探讨热带深对流云对于污染气体的垂直输送作用。分析结果显示,在孤立对流云卷云砧中,云砧内部O3、NO、NOx浓度均大于云外;而CO则不同,只有在近地面浓度高时才如此,在近地面浓度较小时,卷云砧内部的浓度反而小于云外。进一步分析造成这两类气体分布差异的原因,发现CO主要借助深对流云将对流层下层以及对流云周围环境中的CO夹卷并动力垂直输送到对流云顶部卷云砧中,而对于O3、NO和NOx来说,除了上述作用以外,还可能与对流云内部其他物理机制(如闪电),造成新的O3、NO和NOx有关,这些新生气体随着风暴内部强烈的上升气流被最终输送进云砧中。
The concentrations of CO,O3,NO,and NOx within and outside of anvils and their vertical transport in tropical deep convective clouds are analyzed based on aircraft measurements obtained during the ACTIVE (Aerosol and Chemical Transport in tropIcal conVEction) field campaign in Darwin region,Australia,from November 2005 to February 2006,and combined with the back trajectory calculated with NOAA HYSPLIT model.The results show that in single-cell convective clouds,the concentrations of O3,NO and NOx are higher inside anvils than outside,while for CO,this is true only when concentration of CO near the Earth's surface is high,otherwise,the concentration is lower inside anvils than outside.From a further analysis of the possible mechanisms behind these phenomena it is found that the gases are transported and are entrained to the anvil altitudes in the top layers of convective clouds.For O3,NO,and NOx,apart from transport by the deep convective clouds,other mechanisms,such as lightning,which leads to the variation of O3,NO,and NOx chemically,may be responsible for the measured results in the anvil region,that is,all these newly formed gases will be delivered to the upper layers in the convective cores upon formation.