Collaborative Research: A field and laboratory study of the melting processes of icebergs in a Greenland fjord

合作研究：格陵兰峡湾冰山融化过程的现场和实验室研究

基本信息

批准号：
1657601
负责人：
Fiammetta Straneo
金额：
$ 42.54万
依托单位：
University of California-San Diego Scripps Inst of Oceanography
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-15 至 2022-02-28
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1657601&HistoricalAwards=false
关键词：
Collaborative Research field laboratory study

项目摘要

Iceberg calving accounts for half of the mass discharge from the Greenland and Antarctic ice sheets, which has increased dramatically over the last two decades. Through their displacement and progressive melt, these icebergs impact the regional ocean and its ecosystem by affecting its stratification, nutrient and carbon cycling. Freshwater input due to iceberg melt has the potential to impact regional sea-ice distribution and the global overturning circulation. In addition, they pose a threat to local infrastructure and navigation. Notwithstanding their importance, our understanding of where and how icebergs melt is limited and their representation in ocean and climate models is over-simplistic, in part because informed by only a handful of observations. As a result, model-based predictions of iceberg melt rates, of the fate of the melt water, and of its impact on the ocean are highly uncertain. Improved iceberg parameterizations will reduce uncertainties in model-based predictions of the impact of shrinking polar ice caps on the large-scale ocean circulation and marine ecosystems. This is an urgent issue given the projected increase in iceberg discharge from both ice sheets. While the field experiment will take place in Greenland, it is expected that the results will be applicable to Antarctica?s tabular icebergs. One student supported by this project will be exposed to a cutting-edge problem and a multidisciplinary team of researchers. A video package, created by professional producers with experience in educational/environmental material, will be developed as part of this project to illustrate the different methodologies used to address a complex scientific problem and engage a broad audience. The package produced here will include a similar video-documentary, a 360-degree virtual reality video and clips to be distributed to various media venues including social media. In general, the diverse scientific team engaged in this project has an extensive track record of public outreach through media engagement.Current parameterizations of iceberg motion and melt in ocean models typically utilize only surface ocean velocities and properties. This is inconsistent with the notion that much of the iceberg mass flux is concentrated in large icebergs with drafts of several hundred meters. Indeed, recent work by the investigators and others, based on observations, theory and laboratory experiments, has shown that both the motion and the melting of deep-keeled icebergs in a stratified ocean characterized by a vertically sheared flow are not well represented by current parameterizations. While incorporating the impact of sheared flows on parameterizations of iceberg motion is fairly straightforward, the impact of sheared flows on iceberg melt is not. In particular, preliminary laboratory experiments show that the interaction of the sheared flow with the melt plumes that rise at the edge of icebergs is complex - giving rise to non-linear melt responses. Similarly, observations and models of glaciers melting in a stratified ocean have shown that the melt dynamics is strongly affected by the ambient stratification. Based on these recent studies, the hypothesis that melting of icebergs and the distribution of melt water, in the vicinity of the iceberg, are strongly affected by the ambient stratification and vertical shear will be tested. Through a multi-faceted approach that includes field measurements in Greenland and laboratory modeling, this project seeks to identify the leading parameters that impact the distribution of subsurface melt of an iceberg and the release of melt water into the surrounding ocean. An autonomous surface vehicle, the jetyak, and an unmanned aerial vehicle will be used to quantify iceberg melt and map the circulation and distribution of melt water around the iceberg. Idealized laboratory experiments will complement the field measurements and provide quantitative and comprehensive descriptions of the melt. Together, these results will be used to improve iceberg parameterizations to be used in ocean and climate models.

冰山产犊占了从格陵兰和南极冰盖中批量排出的一半，在过去的二十年中，冰山产犊量却大大增加了。这些冰山通过其位移和进行性融化，通过影响其分层，养分和碳循环来影响区域海洋及其生态系统。由于冰山融化而引起的淡水输入有可能影响区域海冰分布和全球倾覆的循环。此外，它们对当地基础设施和导航构成威胁。尽管它们的重要性，但我们对冰山融化的何处和如何有限的理解，并且它们在海洋和气候模型中的代表性过高，部分原因是只有少数观察结果得出。结果，基于模型的冰山熔体速率，熔融水的命运及其对海洋的影响的预测高度不确定。改进的冰山参数化将减少基于模型的预测对大规模海洋循环和海洋生态系统的影响的预测。鉴于两个冰盖的冰山排放预计会增加，这是一个紧迫的问题。虽然现场实验将在格陵兰进行，但预计结果将适用于南极的表格冰山。该项目支持的一名学生将面临尖端问题和一个多学科研究人员团队。由专业制作人创建的具有教育/环境材料经验的专业制作人的视频包将作为该项目的一部分开发，以说明用于解决复杂科学问题并吸引广泛受众的不同方法。此处生产的包装将包括类似的视频纪录片，一个360度虚拟现实视频和剪辑，并将分发给包括社交媒体在内的各种媒体场所。通常，从事该项目的多元化科学团队通过媒体参与具有广泛的公共宣传记录。这与大部分冰山大量通量集中在大型冰山中的观念不一致。实际上，根据观察结果，理论和实验室实验，研究者和其他人的最新工作表明，在以垂直剪切流动为特征的分层海洋中，运动和深冰冰层的融化并不能很好地代表了当前参数。虽然将剪切流对冰山运动的参数化的影响相当简单，但剪切流对冰山熔体的影响却不是。特别是，初步实验室实验表明，剪切流与冰山边缘上升的熔体羽相互作用很复杂 - 引起了非线性熔体响应。同样，在分层海洋中熔化的观测和模型表明，熔体动力学受环境分层的强烈影响。基于这些最近的研究，将测试冰山和冰山附近的熔融水的分布的假设受到环境分层和垂直剪切的强烈影响。通过包括格陵兰和实验室建模的现场测量的多面方法，该项目旨在确定影响冰山的地下熔体分布以及将熔体水释放到周围海洋中的主要参数。自主地面车辆，jetyak和无人驾驶汽车将用于量化冰山融化，并绘制冰山周围熔体水的循环和分布。理想化的实验室实验将补充现场测量结果，并提供熔体的定量和全面描述。总之，这些结果将用于改善在海洋和气候模型中使用的冰山参数化。

项目成果

期刊论文数量（2）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Multi-Sensor Mapping for Low Contrast, Quasi-Dynamic, Large Objects

适用于低对比度、准动态、大型物体的多传感器映射

DOI：
10.1109/lra.2019.2962357
发表时间：
2020
期刊：
IEEE Robotics and Automation Letters
影响因子：
5.2
作者：
Shah, Vikrant;Schild, Kristin;Lindeman, Margaret;Duncan, Daniel;Sutherland, David;Cenedese, Claudia;Straneo, Fiammetta;Singh, Hanumant
通讯作者：
Singh, Hanumant

Subsurface iceberg melt key to Greenland fjord freshwater budget