Climate Engineering by Arctic Winter Cirrus Thinning: Risks and Feasibility (AWiCiT)

北极冬季卷云稀疏气候工程：风险和可行性 (AWiCiT)

• 批准号: 311095914
• 负责人: Professor Dr. Thomas Leisner
• 金额: --
• 依托单位: Institut für Atmosphäre und Klima
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/311095914?language=en
• 关键词: Climate; Engineering; Arctic; Winter; Cirrus

Climate Engineering (CE) methods are discussed as possible instruments to counteract negative climate change impacts. In addition to carbon dioxide removal and solar radiation management, a method that suggests increases in the outgoing longwave radiation by reducing the warming effect of cirrus clouds has been proposed and that we plan to follow up in this proposal. In order to maximize the focus on longwave radiation, we focus on thinning of Arctic cirrus in winter with the goal to answer the following question: Is Arctic winter cirrus thinning (AWiCiT) feasible and what is the maximum extent of cooling that could be achieved? The risks and side effects of AWiCiT will be studied regionally in terms of possible changes in the Arctic stratosphere including possible modifications of the ozone layer and lower-lying clouds by applying the ICON-ART weather-chemistry forecast model. Possible effects on the global circulation, ocean currents and sea ice coverage will be addressed using the coupled aerosol-atmosphere-ocean global climate model MPI-ESM-HAM. In order to address these questions, we need to validate if the current models are good enough to tackle the questions formulated above. In particular, can they reproduce the observed extent and vertical distribution of cirrus in the Arctic winter? What are the transport pathways of natural and seeding ice nucleating particles (INP) under the dynamic conditions of the Arctic winter? They need to be studied in order to estimate the lifetimes of seeding particles in the desired region. Are the altitudes and routes of the high-flying commercial aircraft sufficient to seed an appreciable fraction of Arctic cirrus or should the seeding area be extended to mid-latitudes? Is under these conditions Bismuth-Tri-iodide (BiJ3), the currently proposed seeing aerosol particle the best seeding agent? Cirrus thinning is only effective if the natural cirrus form predominantly by homogeneous freezing of solution droplets. If they mainly form by heterogeneous freezing on INP, seeding could cause an overseeding leading to a warming instead of a cooling. Therefore the cirrus properties, especially in terms of the contribution of heterogeneous freezing to their formation in the present-day climate, need to be assessed.

将气候工程（CE）方法讨论为应对负面气候变化影响的可能工具。除了二氧化碳去除和太阳辐射管理外，还提出了通过减少卷心云的变暖效应来增加长波辐射的增加，并且我们计划在此提案中进行跟进。为了最大程度地提高对长波辐射的关注，我们专注于冬季北极卷心的稀疏，目的是回答以下问题：北极冬季卷卷稀疏（尊敬）是否可行？可以实现的最大冷却程度是多少？通过应用图标 - 艺术天气化学化学预测模型，将在北极平流层的可能变化（包括可能修改臭氧层和下层云的可能修改）方面，在区域内研究风险和副作用。使用耦合的气溶胶 - 大气 - 大洋全球气候模型mpi-esm-ham，将对全球循环，洋流和海冰覆盖的可能影响。 为了解决这些问题，我们需要验证当前模型是否足够好，可以解决上述问题。特别是，他们可以在北极冬季重现卷心卷的观察到的程度和垂直分布吗？在北极冬季的动态条件下，天然和播种冰颗粒（INP）的传输途径是什么？为了估计所需区域中播种颗粒的寿命，需要研究它们。高空商业飞机的高度和路线足以使北极卷心菌的相当一部分播种，还是应该将播种区域扩展到中间纬度？在这些条件下，是否在当前提出的气溶胶颗粒为最佳的接播剂的情况下，bismuth-Tri-odide（BIJ3）是最佳的吗？ 仅当天然cirrus主要通过溶液液滴的均匀冻结而形成天然卷心时，卷心菜稀疏才有效。如果它们主要是通过在INP上进行异质冻结而形成的，则播种可能导致导致变暖而不是冷却。因此，需要评估卷心特性，特别是在异质冻结对它们在当今气候下形成的贡献方面。