High-energy Electron Precipitation Into the atmosphere: an assessment based on balloon-borne observations and model Calculations

高能电子沉淀进入大气：基于气球观测和模型计算的评估

• 批准号: 429584791
• 负责人: Dr. Miriam Sinnhuber
• 金额: --
• 依托单位: Russian Foundation for Basic Research
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/429584791?language=en
• 关键词: energy; Electron; Precipitation; Into; atmosphere

Energetic electrons accelerated in the terrestrial magnetosphere and magnetotail during auroral substorms and geomagnetic storms precipitate into the atmosphere at high latitudes. Primary collision processes with the most abundant species N2, O2, and O lead to the formation of nitric oxides primarily in the mesosphere and upper thermosphere (70—150 km), and start ion- and neutral chemistry reactions affecting many other trace constituents. Nitric oxides can be transported down into the stratosphere below 45 km altitude in large-scale downward motions over polar latitudes during winter, and destroy ozone there in catalytic cycles, the so-called “Energetic particle precipitation indirect effect”. As ozone is one of the key species in radiative heating and cooling of the stratosphere, changes in its composition directly affect stratospheric temperatures and start a chain of dynamical coupling mechanisms affecting atmospheric temperatures and circulation over large areas down to the troposphere. Because of its apparent importance for winter and spring weather systems particularly at high Northern latitudes, it is now recommended, e.g., for model studies initiated by the World Climate Programme WCRP to include energetic particle precipitation in chemistry-climate model studies as part of the natural solar forcing of the climate system. However, recent analyses of the atmospheric ionization rates provided for such model studies based on satellite-based electron flux observations suggest large deficits in these rates, in particular, an underestimation of the atmospheric ionization during and after large geomagnetic storms with high-energy electron precipitation (HEEP) which is particularly large in the stratosphere and lower mesosphere below 60 km.In the frame of this project, we will investigate the impact of HEEP events on the chemical composition, temperatures and dynamics of the middle atmosphere (stratosphere and mesosphere, (10—90 km) by combining atmospheric ionization rates derived from observations of large HEEP events with a long-time balloon data-set going back to 1961 with recent satellite observations of stratospheric and mesospheric trace constituents, and with models of the middle atmosphere of different complexity going from 1-dimensional ion-chemistry, neutral, and radiative-convective models to global chemistry-climate models. In particular, we will address the following two questions:• What is the long-term impact of high-energy electron precipitation on the chemical composition of the middle atmosphere, and due to which processes?• What is the impact of the apparent underestimation of recommended ionization rates as suggested by the recent results on the composition, temperature and dynamics of the middle atmosphere?Results of the project will be of importance for international programs such as WCRP (https://www.wcrp-climate.org), SPARC HEPPA/SOLARIS (http://solarisheppa.geomar.de) and SCOSTEP (http://www.yorku.ca/scostep).

高能电子在极光亚暴和磁暴期间在地球磁层和磁尾加速，沉淀到高纬度的大气中。与最丰富的物种N2，O2和O的主要碰撞过程导致主要在中间层和上部热层（70-150公里）形成氮氧化物，并开始影响许多其他痕量成分的离子和中性化学反应。冬季，一氧化氮可在极地纬度上空大规模向下运动中向下输送到45公里以下的平流层，并在催化循环中破坏那里的臭氧，即所谓的“高能粒子降水间接效应”。由于臭氧是平流层辐射加热和冷却的关键物质之一，其组成的变化直接影响平流层温度，并启动一系列动态耦合机制，影响大气温度和下至对流层的大面积环流。由于其对冬季和春季天气系统的明显重要性，特别是在北方高纬度地区，现在建议，例如，世界气候方案发起的模型研究，将高能粒子降水作为气候系统自然太阳强迫的一部分纳入化学-气候模型研究。然而，最近对基于卫星电子通量观测的这种模式研究所提供的大气电离率的分析表明，这些电离率存在很大的不足，特别是低估了在具有高能电子降水的大磁暴期间和之后的大气电离，高能电子降水在平流层和60公里以下的中间层下部特别大。我们将研究HEEP事件对中层大气的化学成分、温度和动力学的影响（平流层和中间层，（10-90公里）），方法是将从大型HEEP事件观测中得出的大气电离率与可追溯到1961年的长期气球数据集与最近卫星对平流层和中间层微量成分的观测相结合，不同复杂性的中层大气模型从一维离子化学模型、中性模型和辐射对流模型到全球化学气候模型。特别是，我们将解决以下两个问题：·高能电子沉淀对中层大气化学成分的长期影响是什么，以及由于哪些过程？·最近的结果表明，建议的电离率明显低估，这对中层大气的组成、温度和动态有何影响？该项目的成果将对世界气候研究方案（https：//www.example.com）、环境、健康和环境行动计划/SOLARIS（http：solarisheppa.geomar.de）和空间物理学科学委员会（http：//www.yorku.ca/scostep）等国际方案具有重要意义。www.wcrp-climate.org