Presentation
Open/Closed Boundary and Energy Cutoff Latitude for Varying Dst Indices
Space Weather Workshop
(2018)
Abstract
Polar Cap Absorption (PCA) events are triggered by highly-energized solar particles gaining
access to upper regions of Earth's atmosphere at high latitudes. One impact of these events is increased
absorption of high-frequency radio signal. Last year at this conference I presented a poster offering a
thorough review of high-frequency radio wave absorption. An important next step would be a better
understanding of which particles are more likely to gain access to Earth's upper atmosphere as well as
other conditions that could either prevent or allow this access. Hence, as a continuation of my research
of PCA events I have been studying charged particle trajectories through the geomagnetic field using the
process of reverse engineering. In reverse engineering, a charged particle is placed at some important
location near Earth (top of D-region, for example) and allowed to propagate outward. This method was
used, for example, by Smart et al., (2000) to calculate charged particle trajectories, cutoff rigidities,
energy cutoff latitudes, etc. When using reverse engineering, an important consideration is determining
which trajectories are allowed and which are forbidden. This is a straightforward process on the dayside
of the geomagnetic field since trapped particles are easily identified. However, it becomes more
difficult on the nightside. Due to the topology of the magnetotail it can be difficult to determine which
trajectories are allowed and which are forbidden. Smart et al., (2000) mentions several criteria that have
been used to categorize forbidden vs. allowed trajectories. Using the Tsyganenko model of the
geomagnetic field, I investigate the topology of the magnetotail for various geomagnetic activity levels
and how this activity affects the open/closed boundary (OCB) as well as proton energy cutoff latitudes.
This poster will discuss the geomagnetic field generally, with special emphasis on the magnetotail. In
addition, the importance of the OCB and why it can be difficult to map in the magnetotail will be
discussed.
Keywords
- Open/Closed Boundary,
- Polar Cap Absorption,
- Energy Cutoff Latitude
Disciplines
Publication Date
Spring 2018
Location
Boulder, CO
Citation Information
David Alan Smith. "Open/Closed Boundary and Energy Cutoff Latitude for Varying Dst Indices" Space Weather Workshop (2018) Available at: http://works.bepress.com/david-smith/12/