Alfvenic Aurora: Characteristic and Extreme

这是一项更新提案，旨在继续和扩大极光降水的调查和建模，该研究是在2011年3月1日到期的前3年NSF资助AGS-0741344下启动的。 先前资助的结果提供了对极光降水的各种贡献的第一个定量估计。 他们证明，由Alfvénic加速产生的宽带电子沉淀对电离层和高层大气的能量输入有着惊人的贡献。 具体而言，研究表明，阿尔夫维尼克极光随着太阳风驱动力的增加而增加的速度比任何其他类型的极光都要快，亚暴爆发和阿尔夫维尼克极光增强之间存在明显的联系。先前的资助还产生了第一个具有季节依赖性的经验降水模型，并用于真实的时空天气业务。此外，新模型已被证明是一个强大的研究工具，能够解决诸如每种类型的极光的单独季节依赖性以及这些不同的极光类型在亚暴周期过程中如何不同等问题。这项工作建立在DMSP卫星的粒子降水数据的基础上，该小组正在通过其网站（http：//sd-www.jhuapl.edu/Aurora）提供DMSP原始数据、光谱图和增值产品。这是一项为期3年的数据分析和建模工作，旨在解决有关宽带电子沉淀到高纬度高层大气中的几个有趣问题，也称为Alfvenic极光，因为它可能是由Alfvenic加速引起的。一个具体目标是确定和描述极端事件。在地磁暴期间，Alfvénic极光可以在能量通量和沉淀能量方面达到异常值，它们成为最重要的沉淀形式。 另一个目标是进一步探索观测到的阿尔夫维尼克极光发生率随着太阳风驱动的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方面对此进行解释。最后，将进行模拟工作，以帮助解释宽带加速的更迷人的方面之一，在电子能量范围内的一个或两个数量级上具有大致恒定的微分能量通量的趋势。 这些研究将利用涵盖两个以上太阳活动周期的一套全面的卫星粒子降水数据。该项目将确保公众继续获得和改进以研究成果为基础的经验降水模型，该模型是空间气象业务和其他空间科学研究项目的宝贵资产。 该小组已经建立的一个成功的教育活动也将继续为这个项目。

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.