| 项目编号: | 1502934
|
| 项目名称: | GEM: Subauroral Polarization Streams (SAPS): Stormtime Empirical Modeling, Database Generation and Comparison with Rice Convection Model-Equilibrium (RCM-E) |
| 作者: | Phillip Anderson
|
| 承担单位: | University of Texas at Dallas
|
| 批准年: | 2014
|
| 开始日期: | 2015-09-15
|
| 结束日期: | 2018-08-31
|
| 资助金额: | USD270440
|
| 资助来源: | US-NSF
|
| 项目类别: | Continuing grant
|
| 国家: | US
|
| 语种: | 英语
|
| 特色学科分类: | Geosciences - Atmospheric and Geospace Sciences
|
| 英文关键词: | electric field
; ionosphere
; inner magnetosphere
; sap
; evolution
; high altitude
; magnetic field line
; effect
; dusk side
; satellite
; rcm
; space weather disturbance
; magnetosphere
; earth
; atmosphere explorer programs
; first empirical model
; vulnerable technology
; dynamics explorer
; ion pressure gradient
; different stage
; geophysical parameter
; graduate student
; subauroral density
; ionospheric observation
; epoch analysis
; weak magnetic field-aligned current
; ionospheric conductance pattern
; space storm
; magnetic storm
; magnetic field model
; midlatitude ionosphere
; saps evolution
; electric conductance pattern
; electrical conductance
; ion-neutral coupling
; rcm-e model
; high-energy electron
; dense plasma
; electric potential
; saps field
; particular importance
; temporal evolution
; particle precipitation
; geophysical condition
; magnetic field
; subauroral ionospheric plasma
; low-density sub-auroral ionosphere
; defense meteorological satellite
; ionospheric conductance
; magnetosphere-ionosphere system
; important new aspect
; progressive decrease
; outer boundary
; physics-based model
; different local time sector
; empirical model
; mid-latitudes equatorward
; dayside ionosphere
; subauroral polarization stream
; large error
; important aspect
; rice convection model
|
| 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). |
| 资源类型: | 项目
|
| 标识符: | http://119.78.100.158/handle/2HF3EXSE/93221
|
| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
|
|
There are no files associated with this item.
|
| Recommended Citation: | |
Phillip Anderson. GEM: Subauroral Polarization Streams (SAPS): Stormtime Empirical Modeling, Database Generation and Comparison with Rice Convection Model-Equilibrium (RCM-E). 2014-01-01.
|
|
|