Reconstructing Late Holocene Volcanic Aerosol Fluxes from Greenland Ice Cores Collected by the PARCA Project

智力优势：首席研究员将在NASA-NSF北极区域气候评估计划（PARCA）项目的支持下，沿着格陵兰岛自1995年以来收集的五个多世纪冰芯的整个长度，以次年度分辨率分析主要阴离子和阳离子。很少有格陵兰冰芯在亚年分辨率下用离子色谱（IC）连续分析，专门用于量化火山衍生硫酸盐沉积的历史。大多数格陵兰岛的火山历史都是基于电导测量，电导测量是过量硫酸盐（EXS）的代表，但不是直接测量。PARCA的冰芯提供了一个无与伦比的机会，可以将每年解析的格陵兰冰芯EXS历史的数量增加近一倍，这些EXS历史揭示了在过去的两到八个世纪里火山气溶胶零星地注入大气。特别令人感兴趣的是Humboldt和Tunu岩心，它们将分别提供格陵兰岛西北部（~812年记录）和格陵兰岛东北部（~500年记录）首次由IC确定的年度解析EXS历史。格陵兰冰芯的EXS历史，主要反映了北半球和热带火山喷发的输入，对于估计：1)火山气溶胶在平流层的零星注入，形成自然气候强迫机制；2)化石燃料（即煤）燃烧产生的硫酸盐气溶胶的背景浓度缓慢上升，形成人为气候强迫机制至关重要。正在进行的研究试图区分自然强迫机制的贡献与可归因于人类活动的贡献，这些研究需要了解平流层硫酸盐气溶胶负荷的历史以及由此导致的大气光学深度变化。极地冰盖为这一信息提供了最好的档案，但是基于次年分辨率的连续化学分析的准确年代记录是有限的。主要研究人员将从格陵兰岛PARCA的五个冰芯中提取EXS通量历史，这将补充现有记录，并提高过去800年来北半球平流层硫酸盐负荷冰芯指数的质量和细节。更广泛的影响：改进的“冰芯衍生的”火山气溶胶记录将对探索爆炸性火山活动与气候变率之间的关系有价值。该分析将由博士生进行，其结果将构成该博士生博士论文的基础。研究结果将广泛传播给那些寻找代用气候历史的人。冰芯分析的结果，以及冰川面积和体积的测量，将继续被科学家、决策者和利益相关者使用。2002年4月，在第107届国会第二次会议上，首席研究员的冰芯气候历史和冰川退缩结果被列入2002年能源立法的全球变暖讨论中。冰芯研究小组包括博士后、研究生和本科生，他们定期参加实地项目和实验室分析。这个群体积极投身于教育事业。2002年，媒体在100多篇与美国国家科学基金会资助的乞力马扎罗山项目相关的报纸文章中重点报道了冰芯研究。这种曝光已经扩展到电视（CNN，国家地理学会）和广播（BBC世界服务等）的观众。所描述的细节证实，俄亥俄州立大学古气候冰芯研究小组坚定地致力于并积极参与推进发现和理解，同时促进各级的教学、培训和学习。

ABSTRACTMoseley-ThompsonOhio State UniversityOPP-03-52527Intellectual merit: The Principal Investigators will analyze the major anions and cations at sub-annual resolution along the entire lengths of five multi-century ice cores collected since 1995 in Greenland under the auspices of the NASA-NSF PARCA (Program for Arctic Regional Climate Assessment) Project. Few Greenland ice cores have been analyzed continuously at sub-annual resolution by ion chromatography (IC) specifically to quantify the history of volcanically-derived sulfate deposition. Most Greenland volcanic histories are based on conductance measurements that serve as a proxy for, but not a direct measure of, excess sulfate (EXS). The PARCA cores offer an unparalleled opportunity to nearly double the number of annually-resolved Greenland ice core histories of EXS that reveal the sporadic injection of volcanic aerosols into the atmosphere over the last two to eight centuries. Of particular interest are the Humboldt and Tunu cores that will provide the first annually resolved EXS histories determined by IC from northwest Greenland (~812-year record) and northeast Greenland (~500 year record), respectively. The EXS histories from Greenland ice cores, reflecting primarily the input from Northern Hemisphere and tropical eruptions are critical for estimating: 1) the sporadic injection of volcanic aerosols in the stratosphere, creating a natural climate forcing mechanism and 2) the slowly rising background concentrations of sulfate aerosols from the combustion of fossil fuels (i.e., coal), creating an anthropogenic climate forcing mechanism. Ongoing studies that seek to differentiate the contributions of natural forcing mechanisms from those attributable to human activities require knowledge of the history of stratospheric sulfate aerosol loading and the resulting changes in atmospheric optical depth. The polar ice sheets provide the best archive of this information, but well-dated records based upon continuous chemical analyses at sub-annual resolution are limited. The EXS flux histories that the Principal Investigators will extract from the five Greenland PARCA cores will complement existing records and improve the quality and detail of the ice core index of Northern Hemisphere stratospheric sulfate loading over the last 800 years.Broader Impacts: The improved 'ice core-derived' volcanic aerosol records will be valuable to those exploring the relationship between explosive volcanism and climate variability. The analyses will be conducted by a Ph.D. student and the results will constitute the basis for the student's doctoral dissertation. The results will be disseminated broadly to those seeking proxy climate histories. The results from the ice core analyses, as well as the glacier area and volume measurements, continue to be used, by scientists as well as policy makers and stakeholders. The Principal Investigators' ice core-derived climate histories and glacier retreat results were included in the 107th Congress' second session, April, 2002, for global warming discussions to the 2002 energy legislation. The ice core research group includes postdoctoral fellows, graduate students and undergraduates who regularly participate in both their field programs and the laboratory analyses. This group is actively engaged in education. In 2002, media outreach included highlights of the ice core research in more than 100 newspaper articles associated with the NSF-funded Kilimanjaro project. This exposure has extended to television (CNN, National Geographic Society) and radio (BBC World Service, etc.) audiences. The details described confirm that the Ohio State paleoclimate ice core research group is strongly committed to and actively engaged in advancing discovery and understanding while promoting teaching, training and learning at all levels.