| 项目编号: | 1623844
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| 项目名称: | A Helioseismic Study of Active Region Flows and their Contribution to Global Dynamics |
| 作者: | Douglas Braun
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| 承担单位: | NorthWest Research Associates, Incorporated
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| 批准年: | 2017
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| 开始日期: | 2017-01-15
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| 结束日期: | 2019-12-31
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| 资助金额: | 242087
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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: | flow
; contribution
; active-region
; active region
; project
; active-region related flow
; sun
; near-surface
; zonal flow pattern
; global circulation
; part
; flow property
; subsurface
; meridional flow
; magnetic region property
; zonal flow measurement
; solar magnetic region
; active-region related inflow
; flow determination
; active-region-related flow
; larger-scale dynamics
; zonal flow component
|
| 英文摘要: | The survey to be produced as part of this 3-year project will considerably increase our knowledge about the physics of subsurface flows inside the Sun, allowing their variation with magnetic region properties, and with time, to be ascertained. The research program seeks to understand how these flows affect larger circulation patterns, particularly the meridional and zonal flow components of global circulation. The meridional flow is involved critically in the process that leads to Sun's polar field polarity reversals and the ability to predict properties of subsequent solar cycles. It is not clear how it is modulated in time by the contribution of active-region related inflows. A quantitative assessment of this contribution, provided by this research project, will allow critical improvements to be made in predictive models. Theories regarding the physics of the flows have been put forward, with predictions about their variation with depth. These predictions will be tested by the inverse modeling efforts as part of this project. Using artificial data available from numerical MHD simulations, the research activities will also aim to develop and validate methods to infer subsurface flows reliably and which avoid artifacts caused by the influence of surface magnetic fields on the seismic waves. These methods will be invaluable for improving and validating other models of flows and structures inferred through helioseismology.
The main purpose of this 3-year project is to perform a comprehensive, high-spatial-resolution helioseismic survey of subsurface flows around solar magnetic regions in order to improve models of solar dynamo. The research project has four main objectives. The first objective is to characterize, using helioseismic holography applied to Dopplergrams from the Helioseismic Imager onboard the SDO mission, the near-surface flows observed around solar active regions. This characterization will include examining the dependence of the flow properties with magnetic flux. The time dependence of the flows as regions evolve will also be examined. The second objective is to establish and quantify the contribution of the near-surface flows surrounding active regions to the latitudinal- and temporal-variation of the global meridional and zonal flow patterns. This will be achieved by comparing monthly time and longitude averages of active-region related flows with meridional and zonal flow measurements. The third objective is to determine, through helioseismic inverse modeling, the depth dependence of active-region related flows, in order to provide a physical understanding of the flows. The fourth objective is to validate the reliability of the flow determination around active regions. This will be achieved using existing synthetic data derived from state-of-the-art numerical MHD simulations of waves in the vicinity of magnetic structures.
An understanding of the contribution of active-region-related flows in Sun's interior to the larger-scale dynamics is required for improving surface-flux-transport models of the solar dynamo. The outcome of this project is expected to improve general knowledge of solar and stellar dynamos and the evolution of magnetic fields. The expected results will allow improvements in predicting the solar-cycles of the Sun. The project team will broadly disseminate data products for their use in these types of models as part of this program. This project will facilitate continued involvement of the team in the REU Program in Solar and Space Physics hosted by the University of Colorado at Boulder. A considerable portion of this research is being carried out by a postdoctoral research scientist who will take the lead on several of the project tasks. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/90611
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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: | |
Douglas Braun. A Helioseismic Study of Active Region Flows and their Contribution to Global Dynamics. 2017-01-01.
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