Decadal Prediction Following Volcanic Eruptions

大型火山喷发产生的平流层硫酸盐气溶胶可以在喷发后持续一到两年。除了在这段时间内降低全球平均温度外，气溶胶还可以产生区域气候反应，包括热带季风降雨减少、北半球大陆冬季变暖以及厄尔尼诺事件的可能性增加。虽然这些影响可能只会持续一到两年，但对地下海洋温度的影响可能会持续更长时间，对于温跃层以下的水团来说，这种影响可能会持续几十年。本项目旨在确定上述气候后果可预测的程度。虽然火山喷发本身是无法预测的，但注入平流层的硫酸盐的数量可以在喷发后几天内确定，这些信息可能足以确定火山在喷发后几年到几十年的影响。大部分研究工作致力于从多模式组合中识别气候模拟中的火山信号，包括耦合模式比较项目3和5版本（CMIP3, CMIP5），古气候模式比较项目2和3版本（PMIP2, PMIP3）以及NCAR大集合（LE）和过去千年（PM）模拟。作为这项工作的一部分，将评估模拟的几个方面，包括所使用的火山强迫的性质、火山喷发时大气和海洋的状态（就与厄尔尼诺现象和其他气候模式有关的气候波动而言）以及火山喷发对平流层臭氧的影响。在此分析之后，首席研究员和他的团队将使用社区地球系统模型第1版（CESM1）进行一套气候模拟。将进行许多模拟，包括模拟过去的火山爆发和模拟在特定气候状态（例如厄尔尼诺的温暖和寒冷阶段）开始的火山爆发。模拟还将考虑气候影响的可预测性，将其作为火山喷发规模、地点（特别是高纬度与低纬度）和时间的函数。由于火山喷发引起的气候波动可能对人类产生重大影响，这项工作具有更广泛的社会影响。根据该奖项开展的工作可能有助于开发火山爆发后长期气候破坏的预报系统，这将使可能受到不利影响的社区能够做出适应努力。此外，该项目还支持一名研究生和一名博士后研究助理，从而为该研究领域的未来科学劳动力提供支持。

Large volcanic eruptions produce stratospheric sulfate aerosols that can persist for one to two years following the eruption. In addition to a reduction in global-mean temperature over this time period, the aerosols can produce regional climatic responses including reductions in tropical monsoon rainfall, winter warming over the Northern Hemisphere continents, and possibly an increase in the likelihood of El Nino events. While these effects may only last for one or two years, the impact on subsurface ocean temperatures can last longer, up to several decades for water masses below the thermocline.This project seeks to determine the extent to which the above climatic consequences are predictable. While the eruptions themselves are not predictable, the amount of sulfate injected into the stratosphere can be determined within days of an eruption, and this information may suffice to determine the volcanic influence over the years to decades following an eruption.A large part of the research effort is devoted to identifying the volcanic signal in climate simulations from multi-model ensembles including the Coupled Model Intercomparison Project versions 3 and 5 (CMIP3, CMIP5), the Paleoclimate Model Intercomparison Project versions 2 and 3 (PMIP2, PMIP3), and the NCAR Large Ensemble (LE) and Past Millenium (PM) simulations. Several aspects of the simulations will be evaluated as part of this effort, including the nature of the volcanic forcing used, the state of the atmosphere and ocean (in terms of climatic fluctuations associated with El Nino and other climate modes) at the time of the eruption, and the effect of the eruption on stratospheric ozone. Following this analysis the Principal Investigator and his team will conduct a suite of climate simulations with the Community Earth System Model version 1 (CESM1). A number of simulations will be performed including simulations of past volcanic eruptions and simulations of eruptions starting at specific climate states (e.g. the warm and cold phases of El Nino). Simulations will also consider the predictability of climatic effects as a function of the size, location (particularly high latitude versus low latitude), and time of year of the eruption.The work has societal broader impacts due to the substantial human impacts that eruption-induced climate fluctuations can have. Work performed under this award could contribute to the development of a forecasting system for the long-term climatic disruptions following volcanic eruptions, which would enable adaptation efforts for communities likely to be adversely affected. In addition, the project supports a graduate student and a postdoctoral research associate, thereby providing for the future scientific workforce in this research area.