| 项目编号: | 1552321
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| 项目名称: | CEDAR: Characterizing Electron Loss to the Atmosphere Using Multi-point Measurements From Riometers and Spacecraft |
| 作者: | Adam Kellerman
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| 承担单位: | University of California-Los Angeles
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| 批准年: | 2016
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| 开始日期: | 2016-03-01
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| 结束日期: | 2019-02-28
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| 资助金额: | 320165
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Atmospheric and Geospace Sciences
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| 英文关键词: | electron
; atmosphere
; electron production
; riometer absorption datum
; riometer field
; satellite measurement
; energetic electron precipitation
; absorption signature
; absorption
; fractional loss
; riometer network
; riometer absorption
; riometer absorption measurement
; electron energy loss
; precipitation
; different riometer
; riometer site
; upper atmosphere
; population measurement
; relationship
; magnetosphere detector measurement
; energetic electron
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| 英文摘要: | The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program, a broad-based, community-guided, upper atmospheric research program, is aimed at understanding the behavior of atmospheric regions from the lower atmosphere upward through the ionized upper layers of the atmosphere and into the magnetosphere region of outer space. The research funded by this award would analyze the absorption data collected over the past 25 years by a network of 13 riometers located distributed across central Canada with a typical spatial separation of 500 to 2000 km between adjacent sites. These instruments operate at 30 MHz and measure at multiple locations the signal absorption of extraterrestrial cosmic noise radiowave caused by electron production in the altitude range of 75 to 115 km (upper D- and lower E-regions). Two sources of electron production exist in this height range: 1) photoionization and 2) impact-ionization associated with the precipitation of ions and electrons of magnetospheric origin. The loss of the radiowave power received above the Earth's surface at any one time relative to a Quiet Day Curve (which is associated with photo-ionization) is a measure of the absorption to be associated with the precipitation of particles into this ionized region. Calibration of the riometer absorption measurements would be achieved by using measured fluxes of precipitating electrons and measured populations of trapped electrons observed in the radiation belts. This calibration would be based upon the magnetosphere detector measurements derived from tracing the positions of satellite particle energy detectors onboard the Van Allen Probes and the five THEMIS satellites using a sophisticated field-line model of the Earth's magnetic field distribution to determine the magnetospheric footprints of these satellites in situ measurements at various spatial locations across central Canada. The process of selection of riometer absorption data for this calibration process would extract those absorption values associated with the coincidence of the footprint positions with the riometer field of view. The riometer absorption data collected would be analyzed in a statistical sense to establish possible causal relationships between the absorption signature regarding size and shape of absorption and the particular energy band responsible for the particle precipitation into the 90 km region for each riometer site. One relationship that would be searched for in this research is the development of a possible proxy for the extent of magnetospheric wave activity causing the particle precipitation. Another relationship would be the determination from the observed absorption the fractional loss of energetic electrons in the range of tens of keV to MeV energies to the upper atmosphere. A broader impact of this award would be the enhancement of a riometer network as a useful tool with a strong potential for successful application in terrestrial and space weather forecasting.
Comparing riometer absorption with satellite measurements of precipitating electrons will provide for the development statistically of a relationship relating the size and shape of riometer absorption signatures with the energy spectrum of the precipitating particles. The absorption signature results for the different riometers within the network would be used to develop maps of latitudinal and magnetic local time (MLT) distributions of precipitation. Comparison of these signatures with trapped population measurements will quantify the importance of the electron energy loss to the atmosphere, which will help understand the role of energetic electron precipitation in the global system. This study would be coincident with the declining phase of the current solar cycle and will help to demonstrate how low-cost remote sensing of ionospheric precipitation can help understand processes that directly affect the terrestrial and space weather climate. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/92769
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Adam Kellerman. CEDAR: Characterizing Electron Loss to the Atmosphere Using Multi-point Measurements From Riometers and Spacecraft. 2016-01-01.
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