资源环境科技发展态势分析平台

The Volcanic Explosivity Index 5 eruption of the Puyehue-Cordon Caulle volcanic complex (PCC) in central Chile, which began 4 June 2011, provides a rare opportunity to assess the rapid transport and deposition of sulfate and ash from a midlatitude volcano to the Antarctic ice sheet. We present sulfate, microparticle concentrations of fine-grained (similar to 5 mu m diameter) tephra, and major oxide geochemistry, which document the depositional sequence of volcanic products from the PCC eruption in West Antarctic snow and shallow firn. From the depositional phasing and duration of ash and sulfate peaks, we infer that transport occurred primarily through the troposphere but that ash and sulfate transport were decoupled. We use Hybrid Single-Particle Lagrangian Integrated Trajectory back trajectory modeling to assess atmospheric circulation conditions in the weeks following the eruption and find that conditions favored southward air parcel transport during 6-14 June and 4-18 July 2011. We suggest that two discrete pulses of cryptotephra deposition relate to these intervals, and as such, constrain the sulfate transport and deposition lifespan to the similar to 2-3 weeks following the eruption. Finally, we compare PCC depositional patterns to those of prominent low-and high-latitude eruptions in order to improve multiparameter-based efforts to identify "unknown source" eruptions in the ice core record. Our observations suggest that midlatitude eruptions such as PCC can be distinguished from explosive tropical eruptions by differences in ash/sulfate phasing and in the duration of sulfate deposition, and from high-latitude eruptions by differences in particle size distribution and in cryptotephra geochemical composition.

Plain Language Summary This paper describes volcanic ash and sulfate deposition in West Antarctica from the June 2011 Puyehue-Cordon Caulle eruption in Chile. This volcanic eruption was the largest of the 21st century to date and had major impacts on air travel throughout the Southern Hemisphere. Although several publications have described satellite observations of ash in the atmosphere following the eruption, our results provide the first evidence of deposition of ash and sulfate in the high latitudes. We show that transport and deposition occurred rapidly, within similar to 2-3 weeks following the eruption, suggesting that transport of both phases occurred primarily through the troposphere. Here for the first time, we assess a highly resolved record of deposition from a midlatitude eruption in Antarctic snow and make comparisons to several well-documented low-and high-latitude eruptions. We show that ash/sulfate phasing, ash particle size distributions, and geochemistry distinguish this midlatitude eruption from low-and high-latitude eruptions. These detailed characterizations of volcanic products in ice cores can aid in identifying the probable volcanic origins of presently unidentified eruptions in the ice core record, ultimately helping to pinpoint specific volcanoes and to elucidate their effects on past climate.