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Joanna Bridge Montana State University Solar Physics REU Program August 2010

A Comparison Between Magnetic Charge Topology and Local Correlation Tracking of Solar Active Regions. Joanna Bridge Montana State University Solar Physics REU Program August 2010 Advisors: Lucas Tarr, Dr. Dana Longcope. Presentation Overview. Introduction to solar magnetic fields

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Joanna Bridge Montana State University Solar Physics REU Program August 2010

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  1. A Comparison Between Magnetic Charge Topology and Local Correlation Tracking of Solar Active Regions Joanna Bridge Montana State University Solar Physics REU Program August 2010 Advisors: Lucas Tarr, Dr. Dana Longcope

  2. Presentation Overview • Introduction to solar magnetic fields • Developing an approach to partitioning and tracking active regions • Current methods for tracking active region movement • Comparing methodologies • Conclusions and impacts of this research

  3. Magnetograms depict line of sight solar magnetic fields

  4. Magnetograms depict line of sight solar magnetic fields • MDI images were taken at 96 minute intervals • To track active regions, a mask is created that partitions subregions of flux • Potential problems: • Over several days, regions tend to disappear and reappear from time to time • Labels switch seemingly arbitrarily

  5. A reliable algorithm for pole consistency was developed

  6. A reliable algorithm for pole consistency was developed

  7. Three algorithms were used to smooth unruly data • In the end, only two of the original three functions for cleaning up poles were retained • Some hand-fixing of labels was required

  8. Local Correlation Tracking (LCT) is the current method for tracking regions • LCT tracks movement of individual pixels of magnetograms to determine velocities • Potential problems: • Underestimation of areas of stronger flux • Overemphasis on weaker flux regions

  9. Creating the mask currently relies on LCT • Mask regions have commonly been generated starting with the final LCT velocity fields and advecting back to the initial mask • Using this mask to analyze the effectiveness of LCT begs the question since the mask was found using LCT to begin with • Our method for creating the mask depends entirely on tessellation algorithms instead of LCT, allowing for both analysis of LCT and our method

  10. Magnetic Charge Topology (MCT) tracks source movement • MCT is used to approximate the flux regions as flux-weighted centroids • The mask is generated from these sources

  11. Velocities can be determined by tracking pole movement • Centroid velocities: [x(i+1) - x(i)] / [time(i+1) - time(i)]

  12. Comparison between MCT and LCT showed a high degree of correlation

  13. Comparison between MCT and LCT showed a high degree of correlation

  14. Comparison between MCT and LCT showed a high degree of correlation

  15. Comparison between MCT and LCT showed a high degree of correlation

  16. Further analysis confirms this agreement between the two methods

  17. Conclusions/Impacts • Finding a repeatable algorithm to create masks not using LCT is feasible and effective • Comparison of LCT and MCT allows for confirmation of the validity of both methods • Where MCT does not match LCT, there is a reasonable explanation for it • Tracking movement of active regions comes into play in energy storage and helicity calculations

  18. Thank you! • Acknowledgments: • Lucas Tarr • Dana Longcope • NSF • The entire solar physics group here at MSU • My cohorts here this summer

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