Alfvenic Aurora: Characteristic and Extreme

阿尔芬极光：特色与极致

• 批准号: 1045638
• 负责人: Thomas Sotirelis
• 金额: $ 31.12万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1045638&HistoricalAwards=false
• 关键词: Alfvenic; Aurora; Characteristic; Extreme

This is a renewal proposal to continue and expand the investigation and modeling of auroral precipitation that was initiated under the previous 3-year NSF grant, AGS-0741344, which expired on March 1, 2011. Results from the previous grant provided the first quantitative estimates of the various contributions to auroral precipitation. They demonstrated that broadband electron precipitation, created by Alfvénic acceleration, is a surprisingly large contributor to the energy input into the ionosphere and upper atmosphere. Specifically, it was shown that Alfvénic aurora increases faster with increasing solar wind driving than any other type of aurora, and that there is a clear connection between substorm onset and enhanced Alfvénic aurora. The previous grant also produced the first empirical precipitation model with seasonal dependence and with the being used in real time space weather operations. In addition, the new model has proven to be a powerful research tool, capable of addressing issues such as the separate seasonal dependence of each type of aurora, and how these various auroral types differ over the course of a substorm cycle. The work builds on particle precipitation data from the DMSP satellites, and the team is providing DMSP raw data, spectrograms, and value added products from their web site (http://sd-www.jhuapl.edu/Aurora). This is a 3-year data analysis and modeling effort addressing several intriguing questions concerning broadband electron precipitation into the high latitude upper atmosphere, also called Alfvenic aurora because it is presumably caused by Alfvénic acceleration. A specific objective is the identification and characterization of extreme events. During geomagnetic storms Alfvénic aurora can reach exceptional values in energy flux and precipitating energy and they become the most important form of precipitation. Another objective is to further explore an observed exponential rise in Alfvénic aurora occurrence with increased solar wind driving and to explain this in terms of the basic coupling mechanisms between the magnetosphere and ionosphere, and the types of auroral precipitation that result. Finally, a simulation effort will be undertaken to help explain one of the more fascinating aspects of broadband acceleration, the tendency to have roughly constant differential energy fluxes over one or two orders of magnitude in electron energy range. The studies will utilize a comprehensive set of satellite particle precipitation data covering more than two solar cycles. The project will ensure continued public access and improvements to the empirical precipitation model based on the research results that constitutes a valuable asset both for space weather operations and other space science research projects. A successful educational activity that the team has established will also be continued for this project.

这是一项更新提案，旨在继续和扩大极光降水的调查和模拟工作，这项工作是根据2011年3月1日到期的前一笔为期3年的美国国家科学基金会赠款AGS-0741344启动的。前一笔赠款的结果提供了对极光降水各种贡献的第一次定量估计。他们证明了由AlfvéNic加速产生的宽带电子沉淀对输入到电离层和高层大气的能量有令人惊讶的巨大贡献。具体而言，研究表明，阿尔夫尼克极光随太阳风驱动的增加而增加的速度比任何其他类型的极光都要快，而且亚暴爆发和阿尔夫尼克极光增强之间有明显的联系。前一笔赠款还制作了第一个具有季节相关性的经验降水模型，并将其用于实时空间气象业务。此外，新模型已被证明是一个强大的研究工具，能够解决各种类型极光的独立季节相关性以及这些不同类型的极光在亚风暴周期过程中的不同之处等问题。这项工作建立在DMSP卫星的粒子降水数据基础上，该团队从他们的网站(http://sd-www.jhuapl.edu/Aurora).)提供了DMSP的原始数据、光谱图和增值产品这是一项为期3年的数据分析和模拟工作，旨在解决有关宽带电子降水进入高纬度高层大气的几个有趣问题，也被称为阿尔夫维尼极光，因为它可能是由阿尔夫涅克加速引起的。一个具体的目标是确定极端事件的特征和特征。在地磁风暴期间，Alfvénic极光在能量通量和降水能量方面可以达到异常的值，它们成为最重要的降水形式。另一个目标是进一步探讨所观察到的阿尔夫尼克极光事件随着太阳风驱动增加而呈指数上升的现象，并从磁层和电离层之间的基本耦合机制以及由此产生的极光降水类型来解释这一现象。最后，将进行模拟工作，以帮助解释宽带加速的一个更吸引人的方面，即在电子能量范围内，在一到两个数量级范围内具有大致恒定的微分能流的趋势。这些研究将利用覆盖两个以上太阳周期的一套全面的卫星粒子降水数据。该项目将确保公众能够继续利用和改进基于研究结果的经验降水模型，这是空间气象业务和其他空间科学研究项目的宝贵财富。该小组已经建立的成功的教育活动也将为这个项目继续进行。