Solar Cycle, Solar Wind, and Ultraviolet (UV) Control of Substorm Frequency and Magnitude

太阳周期、太阳风和紫外线 (UV) 对亚暴频率和强度的控制

• 批准号: 1353825
• 负责人: Thomas Sotirelis
• 金额: $ 30.5万
• 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: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1353825&HistoricalAwards=false
• 关键词: Solar; Cycle; Wind; Ultraviolet; UV

Magnetospheric substorms are one of the most widely studied and important topics in magnetospheric physics. Substorms are frequent and studies of substorms allow researchers to investigate the basic physics of the dynamics of the solar wind, magnetosphere and ionosphere system. It is well recognized that magnetic reconnection occurs at the dayside magnetopause in the overwhelming majority of substorms and is generally thought to be the main way in which mass, momentum and energy are transported from the solar wind to the magnetosphere. However, other processes can also influence substorm dynamics. This is a proposal to evaluate the importance of the solar wind velocity and ionospheric conductivity on substorm dynamics. It is possible to separate these effects from the effects of reconnection because of the large 30 year data base created by the SuperMAG project. In a substorm the magnetosphere is first preconditioned by the solar wind. This preconditioning has two time scales. In this proposal it is hypothesized that those time scales are influenced by the solar wind velocity. One influence affects the reconnection rate at the dayside magnetopause and the other provides ?seed energy? to the plasma sheet. The investigators also propose to investigate the influence of ionospheric conductivity on substorm preconditioning by studying the effects of solar UV insolation. In particular they will investigate the semi-annual variation of geomagnetic activity with peak activity at the equinoxes and the observation that during substorms stronger auroras occur in the winter hemisphere. They propose to resolve the question of whether dipole tilt (and hence reconnection) drives the equinoctial variation or whether UV insolation is also important. This work will support a young woman scientist just starting her career. The Applied Physics Laboratory has an ongoing program to support summer interns. The database from this study will be very valuable to the overall magnetospheric physics effort.

磁层亚暴是磁层物理学中研究最广泛、最重要的课题之一。亚暴频繁发生，对亚暴的研究使研究人员能够调查太阳风、磁层和电离层系统动态的基本物理学。 众所周知，在绝大多数亚暴中，磁重联发生在昼侧磁层顶，通常被认为是质量、动量和能量从太阳风输送到磁层的主要方式。然而，其他过程也可以影响亚暴动力学。这是一个建议，以评估太阳风速度和电离层电导率的亚暴动力学的重要性。由于SuperMAG项目创建了30年的大型数据库，因此有可能将这些影响与重连的影响分开。在亚暴中，磁层首先受到太阳风的预处理。该预处理具有两个时间尺度。 在这个提议中，假设这些时间尺度受到太阳风速度的影响。一个影响的重联率在向阳面磁层顶和其他提供？种子能量？到等离子板。研究人员还建议通过研究太阳紫外线照射的影响，调查电离层电导率对亚暴预处理的影响。特别是，他们将调查地磁活动的半年变化，在春分点活动达到高峰，并观察到在亚暴期间，冬季半球出现较强的极光。他们建议解决偶极子倾斜（以及因此的重连）是否驱动春分变化或紫外线照射是否也很重要的问题。这项工作将支持一位刚刚开始职业生涯的年轻女科学家。应用物理实验室有一个持续的计划，以支持暑期实习生。这项研究的数据库将对整个磁层物理学工作非常有价值。