Atmospheric chemistry of a 33–34 hour old volcanic cloud from Hekla Volcano (Iceland): Insights from direct sampling and the application of chemical box modeling
Atmospheric chemistry of a 33–34 hour old volcanic cloud from Hekla Volcano (Iceland): Insights from direct sampling and the application of chemical box modeling
复制标题
海克拉火山（冰岛）33-34 小时火山云的大气化学：直接采样和化学盒模型应用的见解
DOI：
10.1029/2005jd006872
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发表时间：
2006
影响因子：
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通讯作者：
J. Ballenthin
中科院分区：
文献类型：
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作者：
W. Rose;Genevieve A. Millard;T. Mather;D. Hunton;B. Anderson;C. Oppenheimer;B. Thornton;T. Gerlach;A. Viggiano;Y. Kondo;T. Miller;J. Ballenthin
2000年2月28日，在SAGE III臭氧损失和验证实验（SOLVE I）期间，DC-8研究飞机对冰岛Hekla火山的火山云进行了偶然取样。它是在发射后33-34小时，在海拔10.4公里（平流层下层）的夜间遇到的。云很容易被大量的SO2(≤1 ppmv), HCl(≤70 ppbv)， HF（≤60 ppbv）和颗粒（可能包括细硅酸盐灰）所识别。我们比较了观测到的和模拟的云成分，以了解它的化学演变。硫和卤素的丰度表明硫气体有一定的氧化作用，但清除和去除卤化物的作用有限。化学模拟表明，在201-203 K，水蒸气和硝酸的云浓度促进了极地平流层云（PSC）的形成，产生冰、三水合硝酸（NAT）、四水合硫酸（SAT）和液态三元溶液H2SO4/H2O/HNO3 （STS）颗粒。我们发现这些火山诱导的PSCs，特别是冰和NAT颗粒，激活了云中的火山成因卤素，产生了bb20 ppbv ClOx。这将在白天早些时候破坏臭氧，与观测到的极低水平的臭氧一致。在那个北极冬天，火山成因的PSCs和氯的结合以比其他PSCs更快的速度破坏了臭氧。云层中HNO3和NOy水平的升高可以用高温和/或火山闪电引起的喷发柱中的大气固氮来解释。然而，观测到的高水平的HOx仍然无法解释，因为云层是在晚上采样的。
[1] On 28 February 2000, a volcanic cloud from Hekla volcano, Iceland, was serendipitously sampled by a DC-8 research aircraft during the SAGE III Ozone Loss and Validation Experiment (SOLVE I). It was encountered at night at 10.4 km above sea level (in the lower stratosphere) and 33–34 hours after emission. The cloud is readily identified by abundant SO2 (≤1 ppmv), HCl (≤70 ppbv), HF (≤60 ppbv), and particles (which may have included fine silicate ash). We compare observed and modeled cloud compositions to understand its chemical evolution. Abundances of sulfur and halogen species indicate some oxidation of sulfur gases but limited scavenging and removal of halides. Chemical modeling suggests that cloud concentrations of water vapor and nitric acid promoted polar stratospheric cloud (PSC) formation at 201–203 K, yielding ice, nitric acid trihydrate (NAT), sulfuric acid tetrahydrate (SAT), and liquid ternary solution H2SO4/H2O/HNO3 (STS) particles. We show that these volcanically induced PSCs, especially the ice and NAT particles, activated volcanogenic halogens in the cloud producing >2 ppbv ClOx. This would have destroyed ozone during an earlier period of daylight, consistent with the very low levels of ozone observed. This combination of volcanogenic PSCs and chlorine destroyed ozone at much faster rates than other PSCs that Arctic winter. Elevated levels of HNO3 and NOy in the cloud can be explained by atmospheric nitrogen fixation in the eruption column due to high temperatures and/or volcanic lightning. However, observed elevated levels of HOx remain unexplained given that the cloud was sampled at night.