GEM: Subauroral Polarization Streams (SAPS): Stormtime Empirical Modeling, Database Generation and Comparison with Rice Convection Model-Equilibrium (RCM-E)

GSTDTAP

项目编号	1502934
	GEM: Subauroral Polarization Streams (SAPS): Stormtime Empirical Modeling, Database Generation and Comparison with Rice Convection Model-Equilibrium (RCM-E)
	Phillip Anderson
主持机构	University of Texas at Dallas
项目开始年	2015
	2015-09-15
项目结束日期	2018-08-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	88043(USD)
国家	美国
语种	英语
英文摘要	During space storms, electric fields and particle precipitation expand into mid-latitudes equatorward of the auroral oval. Electric fields, produced by the interaction of the magnetosphere with the onrushing solar wind ultimately are responsible for the auroral oval but they also cause high-energy electrons and ions to drift deep into the inner magnetosphere. The inner magnetosphere maps along magnetic field lines into the midlatitude ionosphere causing disturbances there. On the dusk side of the inner magnetosphere, the ions penetrate closer to the Earth (and thus to lower latitudes) than the electrons. The weak magnetic field-aligned currents associated with ion pressure gradients at high altitude in space surrounding the Earth close through the low-density sub-auroral ionosphere on the dusk side and in the process produce strong westward electric fields that set the subauroral ionospheric plasma in motion. The electric fields and the drifts they produce in the ionosphere are called subauroral polarization streams (SAPS). The resulting strong ionospheric electric fields map back out along magnetic field lines producing effects in the magnetosphere. This coupling is important in producing space weather disturbances. The proposal will develop an empirical model based on a suite of low-earth orbiting satellites that describes the global distribution of SAPS fields in the ionosphere as a function of solar and geophysical conditions. An important aspect of this work is an investigation of the feedback between the electrical conductance of the ionosphere and the SAPS evolution. The results will contribute to our ability to understand and predict the temporal evolution of space weather disturbances and their impacts on vulnerable technologies. Of particular importance, SAPS draw dense plasma from the dayside ionosphere in plumes up over the polar cap, which can disrupt GPS signals resulting in large errors in global positioning. A graduate student will be trained on the project at the University of Texas. The proposers will use 80 years of ionospheric observations covering different local time sectors taken by satellites in the Defense Meteorological Satellite, Dynamics Explorer, and Atmosphere Explorer Programs. These will be sorted by solar activity and geophysical parameters to construct the first empirical model of subauroral electric fields. The data will also be used in a superposed epoch analysis of magnetic storms to understand the evolution of the SAPS electric fields during different stages of the storm. The RCM-E model, which combines the Rice Convection Model (RCM) with an equilibrium (self-consistent) magnetic field model (E), is a physics-based model that will be used to explore the evolution of the SAPS and test how ionospheric conductance affects this evolution. Given the plasma distribution for each species along with the magnetic field and electric potential at the outer boundary of the inner magnetosphere at high altitude, and the electric conductance pattern in the ionosphere, RCM solves for the electrodynamics of the coupled magnetosphere-ionosphere system. An important new aspect of this work is the focus on the effects of ion-neutral coupling through the changes it produces in the imposed ionospheric conductance pattern (i.e., progressive decrease in subauroral density as the storm progresses).
来源学科分类	Geosciences - Atmospheric and Geospace Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68803
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Phillip Anderson.GEM: Subauroral Polarization Streams (SAPS): Stormtime Empirical Modeling, Database Generation and Comparison with Rice Convection Model-Equilibrium (RCM-E).2015.