Collaborative Research: Establishing Marine Varve Thickness as a Proxy for Annual Alaska Climate Variability and PDO Oscillations, Hubbard Glacier Field Study

合作研究：建立海洋藻类厚度作为阿拉斯加年度气候变化和 PDO 振荡的代理，哈伯德冰川实地研究

• 批准号: 0326926
• 负责人: John Jaeger
• 金额: $ 11.58万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0326926&HistoricalAwards=false
• 关键词: Collaborative; Research; Establishing; Marine; Varve

ABSTRACTCowanOPP-0327106Powell OPP-0327107 JaegerOPP-: 0326926 This is a collaborative proposal by Principal Investigators at the Appalachian State University, Northern Illinois University (NIU), and the University of Florida (UF). A major goal of Arctic science is to quantify the impact of recent climate change on threatened ecosystems and native cultures. In Alaska, this climate forcing by North Pacific (Pacific Decadal Oscillation (PDO); Aleutian Low Pressure (ALPI), and Arctic Oscillation (AO) climate systems is most strongly manifested in decadal-long shifts in Arctic (60degrees-90degreesN) air temperature and precipitation. This has led to pronounced changes in regional oceanography and noticeably in the accelerated melting of Alaskan glaciers, which has been shown to have a global impact on sea-level rise and perhaps on regional freshwater input to the Bering Sea from the Gulf of Alaska. However, the timing and forcing of glacial melting cannot be established, because there are few annual records of meltwater discharge directly from large cliff-calving glaciers to test how glacier melt varies in response to high-frequency climate change over the last two decades.Intellectual Merit: This research will generate annually-resolved climate records in an area where forcing by the PDO and ALPI is strongest and the impact is likely to affect threatened Arctic ecosystems by establishing a correlation between marine varve thickness and local meteorological forcing. Analysis of the proxy climate record at Hubbard Glacier, the largest tidewater glacier in North America, will allow evaluation of what climate variables or indices most closely correlate with annual release of sediment and meltwater. The Hubbard is an ideal glacier for a field study because it is relatively stable, is located in a climatically sensitive region, and there is a long (50+ year) monthly record of local climatology in Yakutat, AK. Annual varves form in proglacial basins adjacent to large tidewater glacier systems along the Gulf of Alaska coast and consist of summer deposition of meltwater-produced laminated mud following winter deposition of a diamicton produced by iceberg rafting. The hypothesis to be tested is that the thickness of the laminated unit is a proxy for summer meltwater discharge from Hubbard Glacier. Preliminary analysis of varve thickness shows a correlation between PDO, ALPI, and sedimentation rate, such that the negative (cold-phase) PDO index correlates with higher winter snowfall leading to increased meltwater discharge later in the summer melt season. After a 1989 regime shift, the varve record also correlates with higher summer precipitation, a characteristic of the post-1989 ALP index. By using these relationships, a 20-year long hypothetical varve record has been produced for testing by collecting ~30 piston cores from Disenchantment Bay. Sedimentological and radiochemical techniques will establish varve thickness and chronology. High resolution seismic reflection profiles will be collected to increase spatial coverage and correlation, which will address how varve thickness varies as a function of distance from the sediment source. The Broader Impacts will include improved understanding of the role of glacial melting in influencing the freshwater discharge to the Gulf of Alaska, which plays a critical role in the health of fisheries within the Gulf of Alaska and Bering Sea. This proposal also emphasizes collaboration among researchers at various stages of their careers, including five undergraduate students, and several graduate students at UF and NIU, to train students in the earth sciences. This project will also contribute to citizen outreach by establishing a partnership with a regional science center in Western North Carolina to produce a photographic display and a lecture series to communicate Arctic climate change as well as methods used to study tidewater glaciers to an adult audience. Two of the reviewers are not convinced that the results of this project will be of large scale significance. They realize that understanding the recent record of meltwater discharge as a function of specific environmental variables is important, as described on page C-10 for example, but this just does not seem important enough. They think that a longer term perspective should have been a stronger and more prominent element of this proposal - with perhaps a smaller effort on the short record and a greater effort on longer records. While the short record is critical for developing the tools to interpret older records, they recommend that this be taken into consideration should this project be funded for only a single field season. Perhaps this should have been written as a three year project, with two field seasons, and more discussion of why and how a longer term data set would help us put modern day glacial retreat into perspective.

Abstract-Cowanopp-0327106Powell OPP-0327107 Jaegeropp-：0326926这是阿巴拉契亚州立大学，北伊利诺伊州大学（NIU）的首席研究人员的合作提议，佛罗里达大学（UF）。 北极科学的主要目标是量化最近气候变化对威胁生态系统和本土文化的影响。在阿拉斯加，北太平洋的这种气候强迫（太平洋际际振荡（PDO）； Aleteian的低压（ALPI）和北极振荡（AO）气候系统最有力地表现出北极（60度（60级）空气温度和降水性的北极变化。加速的阿拉斯加冰川融化对海平面的上升以及区域性淡水的影响产生了全球影响过去的二十年。智能优点：这项研究将在PDO和ALPI强迫最强的区域中每年产生每年解决的气候记录，并且影响可能会通过建立海洋差异厚度和局部气象强迫之间建立相关性而影响受威胁的北极生态系统。对北美最大的潮水冰川哈伯德冰川的代理气候记录的分析将允许评估哪些气候变量或指数与年度沉积物和融化水的释放最紧密相关。哈伯德是实地研究的理想冰川，因为它相对稳定，位于气候敏感的区域，并且在阿克州Yakutat中有漫长的（50年以上）的本地气候记录。在阿拉斯加沿岸沿着大型潮水冰川系统附近的前冰盆地中形成的年度变化，包括冰山漂流产生的二氧化氢蛋白酶后，由融合植物生产的层状泥浆组成。要测试的假设是，层压单元的厚度是从哈伯德冰川出发的夏季融合水的代理。对Varve厚度的初步分析显示了PDO，ALPI和沉积速率之间的相关性，因此负（冷相）PDO指数与较高的冬季降雪相关，导致夏季融化季节晚些时候的融合水排放量增加。经过1989年的转移，Varve记录也与较高的夏季降水相关，这是1989年后ALP指数的特征。通过使用这些关系，通过从不esschandantment湾收集约30个活塞核来测试20年的假设差异记录。沉积学和放射化学技术将建立静态厚度和年表。将收集高分辨率的地震反射曲线以增加空间覆盖范围和相关性，这将解决varve厚度如何随距沉积物源距离的函数而变化。更广泛的影响将包括对冰川熔化在影响阿拉斯加湾的淡水排放中的作用的理解，这在阿拉斯加海湾内的渔业健康中起着至关重要的作用。该建议还强调了研究人员在职业生涯的各个阶段之间的合作，包括五名本科生，以及UF和NIU的几位研究生，以培训地球科学的学生。该项目还将通过与北卡罗来纳州西部的区域科学中心建立合作伙伴关系来制作摄影展示和讲座系列，以传达北极气候变化以及用于研究潮水冰川与成年受众的方法，从而为公民推广提供了贡献。两个审阅者不相信该项目的结果将具有很大的意义。他们意识到，如第C-10页所述，了解最新的融合水排放记录是特定环境变量的函数，这一点很重要，但这似乎还不够重要。 他们认为，长期的观点本来应该是该提案的更强大，更突出的要素 - 在短期记录上可能会较小，并且在更长的记录上做出了更大的努力。 虽然简短的记录对于开发解释旧记录的工具至关重要，但他们建议如果仅在一个野外季节进行资助，则考虑到这一点。也许这应该是一个三年的项目，有两个田间季节，并且对为什么和如何以及如何以及如何有助于我们将现代冰川撤退置于透视上的原因和方式。