Assessing Atmospheric Impacts of the Hunga Tonga-Hunga Ha'apai Volcanic Eruption and Using It as a Natural Experiment to Evaluate an Earth System Model

火山喷发可以通过几种不同的机制影响天气和气候。例如，极具爆炸性的喷发，就像芒特山那样。皮纳图博在1991年发现的，经常在地球大气层中产生高含硫的液滴和颗粒。在那里，这些气溶胶将阳光散射回太空，可以在一年多的时间里让全球气候降温。2022年1月15日，匈牙利-汤加-匈牙利哈阿派火山在南太平洋爆发。卫星观测显示，这次喷发给大气带来的硫磺少得惊人，但却向地球表面上方约10-20英里的平流层注入了大量的水蒸气。水蒸气是一种温室气体，当它处于平流层时，对气候变暖特别有效，因为平流层通常只存在微量的水。这次喷发使全球平流层水蒸气总量增加了约10%，是迄今从太空观察到的最大单源平流层水蒸气注入，而且这种过剩的水可能会持续5-10年。因此，汤加火山喷发是对地球大气的一次史无前例的自然实验。这项调查将使用观测和建模来评估喷发对大气的影响，包括通过改变地球吸收和发射的太阳光和红外能量对地球能量收支的影响。研究人员将评估喷发如何影响平流层温度、整个大气的环流模式，以及南极洲上空每年形成的臭氧空洞，这可能会受到与喷发相关的化学和物理机制的干扰。更广泛地说，该项目将评估地球系统模型在多大程度上很好地捕捉到火山喷发后几年观测到的地球大气扰动，并确定对模型的改进以弥补已发现的任何不足之处。从更广泛的意义上说，该项目将有助于更好地了解大型火山喷发对全球社会造成的大气和气候影响和风险，特别是像2022年汤加事件这样在海洋表面之下喷发的火山。格陵兰和南极洲冰芯记录的过去火山活动记录表明，比2022年汤加事件强大十倍的火山喷发大约每625年发生一次，可能会对文明造成严重影响。参与该项目的科学家将对这类事件进行模拟，以探索它们的潜在影响。他们还将调整地球系统模型，以便科学界可以更容易地使用它来全面研究火山喷发的气候影响，例如通过提高该模型跟踪和隔离火山水蒸气、硫磺和火山灰的影响的能力。最后，研究人员将为该项目培训和指导一名博士生，并扩大研究生和本科生课程中提供的关于火山-气候相互作用的材料。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Volcanic eruptions can affect weather and climate through several different mechanisms. For example, highly explosive eruptions, like that of Mt. Pinatubo in 1991, often produce sulfur-containing droplets and particles high in Earth’s atmosphere. There, these aerosols scatter sunlight back to space and can cool global climate for more than a year. On January 15, 2022, the Hunga Tonga–Hunga Ha'apai volcano erupted explosively in the South Pacific. Satellite observations showed that the eruption introduced surprisingly little sulfur to the atmosphere but injected an enormous amount of water vapor into the stratosphere, about 10-20 miles above Earth’s surface. Water vapor is a greenhouse gas and is particularly effective at warming climate when it is in the stratosphere, where only trace amounts of water generally exist. The eruption increased the total global stratospheric water vapor content by roughly 10%, representing the largest single-source injection of stratospheric water vapor ever observed from space, and furthermore this excess water could persist for 5-10 years. The Tonga eruption therefore represents an unprecedented natural experiment on Earth’s atmosphere. This investigation will use observations and modeling to assess the atmospheric impacts of the eruption, including its effects on Earth’s energy budget via alterations to the amount of sunlight and infrared energy absorbed and emitted by the planet. The investigators will assess how the eruption affected stratospheric temperatures, circulation patterns throughout the atmosphere, and the annual ozone hole formation over Antarctica, which may be perturbed through chemical and physical mechanisms related to the eruption. More broadly, this project will evaluate how well an Earth System Model captures the observed perturbations to Earth’s atmosphere in the years following the eruption and identify improvements to models that remedy any deficiencies that are found.In a broader sense, this project will contribute to an improved understanding of the atmospheric and climate impacts and risks to global society posed by large volcanic eruptions, particularly those that erupt beneath the ocean surface like the 2022 Tonga event. Records of past volcanic activity recorded in ice cores from Greenland and Antarctica indicate that eruptions ten times more powerful than the 2022 Tonga event occur roughly once every 625 years, with potentially severe impacts on civilization. The scientists involved in this project will conduct simulations of such events to explore their potential impacts. They will also adapt an Earth System Model so that it can be used more readily by the scientific community to comprehensively study climate impacts from volcanic eruptions, for example by improving the ability of the model to track and isolate the influences of volcanic water vapor, sulfur, and ash. Finally, the investigators will train and mentor a Ph.D. student for this project and expand the material on volcano-climate interactions presented in the graduate- and undergraduate-level courses.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.