Trace gas transport and scavenging in PEM‐Tropics B South Pacific Convergence Zone convection
Trace gas transport and scavenging in PEM‐Tropics B South Pacific Convergence Zone convection
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PEM-Tropics B 南太平洋辐合区对流中的痕量气体传输和清除
DOI：
10.1029/2001jd000328
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发表时间：
2001
影响因子：
--
通讯作者：
R. Talbot
中科院分区：
文献类型：
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作者：
K. Pickering;A. Thompson;Hyuncheol Kim;A. Decaria;L. Pfister;T. Kucsera;J. Witte;M. Avery;D. Blake;J. Crawford;B. Heikes;G. Sachse;S. Sandholm;R. Talbot
对1999年太平洋使命（PEM）热带B使命第10次飞行的化学传输进行的分析澄清了南太平洋辐合带（SPCZ）在确定西南热带太平洋臭氧和其他痕量气体分布方面的作用。SPCZ被发现是一个障碍，在对流层低层的混合，但对流混合的热带边界层空气从东北的SPCZ与对流层高层空气从西部到达的机制。一个二维的云解析模型被用来量化三个关键过程中的全球和区域运输：对流混合，闪电氮氧化物的生产，和湿清除可溶性物种。非常低的NO和O3热带边界层空气从东北侧的SPCZ进入对流上升气流，并被输送到对流层上部，在那里它与亚热带对流层上部的空气混合，含有更大的NO和O3的混合比，已抵达澳大利亚。飞机观测表明，SPCZ对流内的放电似乎产生了很少的NO。我们估计，至少有90%的HNO3和H2O2，本来在对流层上部的云流出已被删除，通过云的运输过程中。对于可溶性较低的物质（例如，对于CH3OOH，<50%）。由于低NO边界层空气的向上输送和外流，对流层上层的臭氧净产生率下降了60%。然而，这种外流与云西南边缘的高得多的NO空气包混合，混合物最终具有介于SPCZ两侧气团之间的净臭氧生产潜力。
Analysis of chemical transport on Flight 10 of the 1999 Pacific Exploratory Mission (PEM) Tropics B mission clarifies the role of the South Pacific Convergence Zone (SPCZ) in establishing ozone and other trace gas distributions in the southwestern tropical Pacific. The SPCZ is found to be a barrier to mixing in the lower troposphere but a mechanism for convective mixing of tropical boundary layer air from northeast of the SPCZ with upper tropospheric air arriving from the west. A two-dimensional cloud-resolving model is used to quantify three critical processes in global and regional transport: convective mixing, lightning NOx production, and wet scavenging of soluble species. Very low NO and O3 tropical boundary layer air from the northeastern side of the SPCZ entered the convective updrafts and was transported to the upper troposphere where it mixed with subtropical upper tropospheric air containing much larger NO and O3 mixing ratios that had arrived from Australia. Aircraft observations show that very little NO appears to have been produced by electrical discharges within the SPCZ convection. We estimate that at least 90% of the HNO3 and H2O2 that would have been in upper tropospheric cloud outflow had been removed during transport through the cloud. Lesser percentages are estimated for less soluble species (e.g., <50% for CH3OOH). Net ozone production rates were decreased in the upper troposphere by ∼60% due to the upward transport and outflow of low-NO boundary layer air. However, this outflow mixed with much higher NO air parcels on the southwest edge of the cloud, and the mixture ultimately possessed a net ozone production potential intermediate between those of the air masses on either side of the SPCZ.