Plasmaspheric Pi2 Pulsation Enhancement in Response to Plasma Sheet Pi2 Wave Source: Statistical Study Using Van Allen Probes and THEMIS Conjunctions
Abstract
To understand the enhancement of Pi2 pulsations inside the plasmasphere in response to the plasma sheet Pi2 wave source, we conduct a statistical investigation of 208 conjunction events by using simultaneous two‐point measurements with one satellite located in the plasmasphere and the other one located in the plasma sheet. All the events had a Pi2 compressional wave source observed in the plasma sheet as indicated by their association with bursty bulk flows (BBFs), but for about 25% of the events there were no corresponding enhancements in plasmaspheric Pi2 waves. For events with plasmaspheric Pi2 wave enhancements, a cavity or virtual resonance was likely the dominant wave mode, while excitation of field line resonance was also observed. We select two groups of events: strong (weak) group with the plasmaspheric compressional wave enhancements above 75% percentile (below 25% percentile), and conduct a statistical‐significance evaluation of the differences between the two groups. The strong events were observed closer to midnight than the weak events. The plasma sheet wave source that has a larger wave amplification or larger dipolarization associated with BBFs is more likely to excite stronger plasmaspheric wave enhancements. The strong events occurred more often with a pre‐condition of lower Auroral Electrojet (AE)* levels than did weak events. We explain these dependencies as strong events being associated with more favorable conditions that allow the inward‐propagating compressional waves from the plasma sheet wave source to reach the plasmapause and excite the plasmaspheric waves.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 01, 2022
- Source ID
- 10.1029/2022ja030399
Entities
People
- Chih-Ping Wang
- Jacob Bortnik
- Kazue Takahashi
- Xiaoyan Xing
Organizations
- Air Force Office of Scientific Research
- Johns Hopkins University
- National Aeronautics and Space Administration
- National Science Foundation