Postdoctoral Fellowship: EAR-PF: Establishing a new eruption classification with a multimethod approach

博士后奖学金：EAR-PF：用多种方法建立新的喷发分类

• 批准号: 2305462
• 负责人: Johanand Gilchrist
• 金额: $ 18万
• 依托单位: Gilchrist, Johanand Thiru
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2305462&HistoricalAwards=false
• 关键词: Postdoctoral; Fellowship; EAR; PF; Establishing

Explosive volcanic eruptions produce ground-hugging hot rock and gas avalanches (pyroclastic density currents, PDCs) that devastate local communities and umbrella-shaped ash and gas clouds (umbrella clouds) that threaten aviation and can cause abrupt climate shifts lasting years. The severity and duration of eruption hazards to society, which can last years and affect the entire globe, depend on fluctuations in the rate at which erupted mass exits the volcano (mass eruption rate) and micrometer scale processes. Current eruption classifications do not consider the effects of varying mass eruption rate during an eruption nor micrometer-scale processes on eruption hazards and are, therefore, ill-equipped for informing eruption response plans. The advancements of satellite and ground-based remote-sensing methods to monitor eruptions in real-time combined with increasingly sophisticated eruption computer simulations provide exciting new ways to classify eruption behavior and inform real-time eruption response. However, leveraging these advances in eruption monitoring and modelling methods requires development of basic multiphase fluid mechanics theory to simply characterize the effects of variations in mass eruption rate and micrometer-scale processes in governing eruption behavior. Dr. Johan Gilchrist proposes to develop new fluid mechanics theory that will form the basis for a new “Eruption Stability Diagram” classification that captures the effects of varying mass eruption rate and micrometer-scale processes to predict the evolution of hazards during an eruption. Dr. Gilchrist will conduct the next generation of laboratory experiments and computer simulations and compare the results with remote-sensing observations of eruptions to explore the full range of expected eruption behaviors and hazards for historical, ancient, and future eruptions in the Eruption Stability Diagram. The laboratory experiments will provide a rich learning experience for a diverse group of employed undergraduate researchers. The project includes a collaboration with the National Museum of Natural History (Smithsonian Institute) to develop public-friendly versions of the Eruption Stability Diagram to clearly communicate eruption behaviors, hazards, and mitigation strategies to policymakers and the public. During explosive volcanic eruptions rocks, ash and gases spreading in the atmosphere as umbrella ash clouds and along the ground as deadly pyroclastic density currents (PDCs) threaten people, infrastructure and drive major shifts in climate. In large eruptions volcanic material is simultaneously partitioned to spreading umbrella ash-clouds and PDCs. Furthermore, during individual eruptive phases the rate at which erupted material is delivered to the atmosphere from a volcano can vary significantly compared to time-averaged mean rates (“unsteady eruption source parameters”, ESPs), causing mass partitioning to be highly time-dependent. Popular eruption classifications neither consider eruptive mass partitioning nor address the time-dependence that is inherent to most eruptive phases. Dr. Gilchrist proposes to work with Dr. Josef Dufek (University of Oregon; UO) and Dr. Benjamin Andrews (Smithsonian Institute; SI) to develop in greater detail two new eruption source parameter metrics that Dr. Gilchrist discovered during his PhD: the jet stability number to capture multiphase jet strength and the source Pulsation number to capture source unsteadiness, and combine them with the source particle volume fraction to form a new three-dimensional (3D) “Eruption Stability Diagram” classification scheme. At UO Drs. Gilchrist and Dufek will design, build and conduct the next generation of analog experiments on multiphase jets to test the Eruption Stability Diagram’s reliability for predicting mass partitioning in multiphase jets between spreading clouds and ground-hugging gravity currents. Concurrently, they will work with Dr. Eric Breard (U. of Edinburgh) to validate the next generation of 3D multiphase flow (MFIX) computer simulations using the experimental dataset. They will also collaborate with volcano radar expert Dr. Franck Donnadieu (U. Clermont Auvergne, France) to use a Doppler radar-based dataset of unsteady ESPs that were measured in-situ at Sabancaya volcano, Peru (2018) to run and validate 3D MFIX eruption simulations. This research project aligns with the study of volcanology in the Petrology and Geochemistry program in the Earth Science division of NSF and the EAR research theme “issues related to scales”. The Eruption Stability Diagram will be the first construct to classify all eruption styles on the basis of mean or time-varying eruption source parameters, predict erupted mass delivered to umbrella clouds and PDCs and, in turn, improve forecasting of eruption hazards and volcano-climate effects, generally. Moreover, characteristic evolutions of eruption source parameters typical of many eruptive phases will trace unique paths through the Eruption Stability Diagram allowing classes of eruptions to be understood through their evolution, a novel new way to classify eruptions. This second way of classifying eruptions may reveal eruptive evolutionary paths diagnostic of specific volcanoes, types of volcanoes, or tectonic environments. The Eruption Stability Diagram will replace the current most popular Volcanic Explosivity Index classification used widely to understand the size and effects of volcanic eruptions on Earth. This project will also advance the multimethod approach of using complementary analog experiments and numerical simulations validated with field data to investigate volcanic phenomena. The analog experiments will be the first to facilitate dissection of the deposit constructed by multiphase jets with varying source parameters to identify deposit features that are diagnostic of eruption column regimes and regime transitions, which will guide eruption deposit field studies. In parallel, the new 3D MFIX simulations will push the limits of multiphase flow simulations by explicitly modeling centimeter-scale particle inertial and buoyancy effects on the kilometer-scale bulk flow. Crucial for eruption monitoring, the ESP and synthetic Doppler radar datasets produced by MFIX simulations of eruptions will be publicly available to inform interpretation of volcanic radar data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

火山喷发会产生紧贴地面的热岩和气体雪崩（火山碎屑密度流，PDC），摧毁当地社区，并产生伞状火山灰和气体云（伞云），威胁航空并可能导致持续数年的气候突变。喷发对社会造成危害的持续时间可能会持续数年并影响整个地球，这取决于喷发物质离开火山的速度的波动（质量目前的喷发分类没有考虑喷发过程中不同质量喷发率的影响，也没有考虑微米级过程对喷发危险的影响，因此无法为喷发响应计划提供信息。实时监测喷发的地面遥感方法与日益复杂的喷发计算机模拟相结合，提供了令人兴奋的新方法来对喷发行为进行分类并告知实时喷发响应。然而，利用喷发监测和建模方法的这些进步需要发展基本的多相流体力学理论，以简单地表征质量喷发速率的变化和控制喷发行为的微米级过程的影响。Johan Gilchrist 博士建议开发新的流体力学。该理论将构成新的“喷发稳定性图”分类的基础，该分类捕捉不同质量喷发速率和微米级过程的影响，以预测喷发期间危险的演变。进行下一代实验室实验和计算机模拟，并将结果与​​喷发的遥感观测进行比较，以探索喷发稳定性图中历史、古代和未来喷发的全部预期喷发行为和危害。该项目包括与国家自然历史博物馆（史密森学会）合作开发公众友好版本的喷发稳定性图，以清楚地传达喷发情况。火山喷发期间，岩石、火山灰和气体以伞状灰云的形式在大气中扩散，并以致命的火山碎屑密度流 (PDC) 的形式沿着地面传播，威胁人类、基础设施并推动重大转变。在大规模喷发中，火山物质同时被分散为伞状火山灰云和 PDC。此外，在各个喷发阶段，喷发物质被输送到火山灰的速率。与时间平均平均速率（“不稳定喷发源参数”，ESP）相比，火山的大气可能存在显着变化，导致质量分配高度依赖于时间，流行的喷发分类既不考虑喷发质量分配，也不解决时间依赖性。 Gilchrist 博士建议与 Josef Dufek 博士（俄勒冈大学；UO）和 Benjamin Andrews 博士（史密森学会；SI）合作，在更大范围内进行开发。详细介绍了 Gilchrist 博士在攻读博士学位期间发现的两个新的喷发源参数指标：捕捉多相射流强度的射流稳定性数和捕捉源不稳定性的源脉动数，并将它们与源颗粒体积分数结合起来形成新的三-维（3D）“喷发稳定性图”分类方案 在俄勒冈大学，Gilchrist 和 Dufek 博士将设计、构建并进行下一代多相射流模拟实验，以测试喷发稳定性图的可靠性。同时，他们将与 Eric Breard 博士（爱丁堡大学）合作，使用实验数据集验证下一代 3D 多相流 (MFIX) 计算机模拟。他们还将与火山雷达专家 Franck Donnadieu 博士（法国克莱蒙奥弗涅大学）合作，使用基于多普勒雷达的不稳定 ESP 数据集进行测量。在秘鲁萨班卡亚火山现场运行和验证 3D MFIX 喷发模拟 该研究项目与 NSF 地球科学部门岩石学和地球化学项目中的火山学研究以及 EAR 研究主题“相关问题”相一致。喷发稳定性图将是第一个根据平均或随时间变化的喷发源参数对所有喷发类型进行分类、预测喷发的结构。通常，许多喷发阶段典型的喷发源参数的特征演变将通过喷发稳定性图追踪独特的路径，从而允许分类。通过火山喷发的演化来理解喷发，这是一种对喷发进行分类的新颖方法，这第二种对喷发进行分类的方法可能会揭示特定火山、火山类型或喷发的演化路径诊断。喷发稳定性图将取代目前广泛用于了解火山喷发对地球的规模和影响的最流行的火山爆炸指数分类，该项目还将推进使用经现场验证的互补模拟实验和数值模拟的多方法方法。模拟实验将首次促进对具有不同源参数的多相射流构造的沉积物进行解剖，以识别可诊断喷发柱状态的沉积物特征。同时，新的 3D MFIX 模拟将通过明确模拟对喷发至关重要的厘米级粒子惯性和浮力效应来突破多相流模拟的极限。监测、由 MFIX 模拟喷发产生的 ESP 和合成多普勒雷达数据集将公开，以便为火山雷达数据的解释提供信息。该奖项反映了 NSF 的法定要求使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。