Open-Closed Magnetic Field Line Boundary Identification Using Directional Derivatives of SuperDARN Convection Flow

• Author / Creator

  Hoque, SNM A

• This thesis is a case study analysis to better understand magnetospheric dynamics and in particular dynamics of the open-closed magnetic field line boundary (OCB). The directional derivatives of ionospheric convection flow speed are measured along streamlines using SuperDARN HF radar to determine the open-closed magnetic field line boundary (OCB). It is found that the peak in the directional derivative of SuperDARN flow along a flow streamline may be associated with magnetic reconnection between open and closed field lines and thus is a signature of the OCB.In the first case study, the peak in the directional derivative of SuperDARN flow is compared in all magnetic local time sectors with other OCB proxies such as ultra-violet auroral emission boundaries and particle precipitation boundaries during the southward interplanetary magnetic field condition. The OCB proxy determined with the the directional derivative of SuperDARN flow is found to be consistent with other OCB proxies during the interval. In the second case study, the proposed technique is further evaluated during two different substorm events, with each event interval lasting two hours. The latitudinal locations of the peak in the directional derivative of SuperDARN flow are in agreement with the spectrographic imager’s poleward boundaries of ultra-violet emissions in the dawn and dusk sectors during the substorm intervals. In the final part of the thesis, multiple peaks in the directional derivative of flow during the substorm interval are examined and compared with ultraviolet detectors in the midnight sector. The occurrence of multiple flow peaks in the directional derivative of flow depends on the convection cell pattern which in turn depends upon the IMF By condition. The result indicates that the secondary peaks agree with the ultraviolet measurements in the midnight sector. Therefore, SuperDARN convection flow directional derivatives might be useful for determining the OCB globally.

• Subjects / Keywords

  • SuperDARN
  • Open-Closed Field Line Boundary
  • Directional derivative technique

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3KW57S25

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.