Study of Cross Polar Cap Potential Behavior During Storms and Superstorms Using Defense Meteorological Satellite Program (DMSP) Data

使用国防气象卫星计划 (DMSP) 数据研究风暴和超级风暴期间跨极冠潜在行为

• 批准号: 0637791
• 负责人: Marc Hairston
• 金额: $ 21.5万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2010-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0637791&HistoricalAwards=false
• 关键词: Study; Cross; Polar; Cap; Potential

One of the key features in the coupling of the solar wind to the magnetosphere and the magnetosphere to the ionosphere coupling is the electric potential drop imposed across the polar cap. This potential drop and its associated potential distribution pattern in the polar ionosphere serves as a proxy measurement of the coupling between the solar wind and the magnetosphere. Recent work has shown that the polar ionosphere behaves differently under the extreme solar wind conditions that produce the very large magnetic storms known as superstorms as compared with the behavior during quiet times and moderate magnetic storms. It appears that the polar cap potential drop saturates at a set level no matter how strong the system is driven by the electric field carried by the solar wind. In addition the size of the polar cap itself appears to stop expanding under these saturated potential conditions. Understanding the behavior of the polar cap potential and the size of the polar cap itself and how they respond to solar wind drivers (the solar wind electric field and the solar wind ram pressure) as well as to the changes in the conductivity in the ionosphere are key to understanding the underlying physics of the phenomenon and in developing accurate and reliable models of the geospace environment. This three-year project will use the database of polar ionospheric parameters from the DMSP spacecraft to explore the polar ionosphere's response to regular storms and to the extreme superstorms. The project will develop an empirical model of the size of the polar cap as a function of the magnitude of the polar cap potential and various solar wind inputs. Periods of medium to high values of the solar wind electric field will be examined to determine the transition region where the saturation of the potential begins to appear. The project will also compare the ionospheric Pedersen conductivity derived from the Hill-Siscoe model with the value derived using the AMIE

太阳风与磁层和磁层与电离层耦合的关键特征之一是施加在极冠上的电势降。极地电离层中的这种电势降及其相关的电势分布模式是太阳风和磁层之间耦合的替代测量。最近的研究表明，极地电离层在极端太阳风条件下的行为与在平静时期和中等磁暴期间的行为不同，这种极端太阳风条件会产生被称为超级风暴的非常大的磁暴。看来，无论太阳风携带的电场驱动系统的强度有多大，极帽电位降都会在设定的水平上饱和。此外，在这些饱和的势能条件下，极冠本身的大小似乎停止了膨胀。了解极冠电势的行为和极冠本身的大小，以及它们如何对太阳风驱动因素(太阳风电场和太阳风冲击波压力)以及电离层电导率的变化作出反应，对于了解这一现象的基本物理和制定准确可靠的地球空间环境模型至关重要。这一为期三年的项目将使用DMSP航天器的极地电离层参数数据库来探索极地电离层对常规风暴和极端超级风暴的反应。该项目将开发一个极冠大小与极冠潜力大小和各种太阳风输入的函数关系的经验模型。太阳风电场的中值到高值的周期将被检查，以确定开始出现电势饱和的过渡区。该项目还将比较从Hill-Siscoe模型得出的电离层Pedersen电导率与使用AMIE得出的值