Exploring Solar Wind Influence on Earth's Magnetosphere Dynamics: Insights into the Cusp and Magnetotail Interactions
Nitya Agarwala
PhD Candidate
Catholic University of America
Graduate Research Assistant
NASA Goddard Space Flight Centre.
Wed, October 16, 2024 ~ 4:00 PM
The solar wind interacts with the magnetosphere in various ways, including magnetic reconnection, particle injection, and plasma flows. To fully comprehend these complex processes, it is essential to study the interactions occurring at both the dayside and nightside regions. In this seminar, we focus on two key aspects: flux transfer events (FTEs) in the dayside cusp region and earthward traveling flux ropes (FRs) in the nightside magnetotail, providing a comprehensive picture of solar wind-magnetosphere interactions from dayside to nightside.
In the magnetotail, earthward traveling FRs, characterized by their helical magnetic fields and asymmetric bipolar BZ signatures, play a central role in magnetotail dynamics. Utilizing MMS’s multi-point, high-resolution measurements, we investigate the dissipation of these FRs through magnetic reconnection at the leading edge, focusing on erosion processes, ion and electron energization, and the structure surrounding the reconnection X-line. Our analysis reveals how the weakening southward BZ field at the FR’s leading edge interacts with ongoing lobe reconnection, generating the asymmetric BZ signatures observed in many earthward-moving FRs. This erosion leads to the eventual dissipation of FRs, contributing to geomagnetic dipolarization and particle transport into the inner magnetosphere.
We also explored particle energization processes, with a particular focus on the quantity J · E′, representing the "dissipation quantity." This plays a key role in understanding magnetic reconnection, as it quantifies the dissipation of magnetic energy into kinetic energy and heat. This dissipation occurs within the electron-scale region around the reconnection site, especially near the X-line, where magnetic fields break and reconnect.
On the dayside, multiple magnetic reconnection at the magnetopause creates flux rope-like structures known as FTEs, which fill with energized magnetosheath plasma. These structures serve as conduits for ionospheric particle precipitation, especially in the high-latitude cusp region. Using data from the Cluster mission, which traverses the cusp, we examine cusp plasma filaments—low-latitude, high-altitude signatures of FTEs. Employing multi-spacecraft analysis techniques such as curlometer and minimum variance analysis, we reconstruct the internal plasma structure and dimensionality of these filaments, linking them to localized reconnection events at the dayside magnetopause. Our preliminary results suggest that these cusp filaments represent magnetospheric extensions of FTEs, influencing particle precipitation in the cusp.
By combining the detailed analysis of FR dynamics in the magnetotail and cusp filament structures in the dayside magnetosphere, this study provides new insights into how solar wind-driven reconnection processes affect Earth's magnetospheric boundaries. The findings enhance our understanding of flux rope dissipation, particle acceleration, and the role of FTEs in coupling the solar wind with Earth’s magnetosphere.
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