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Abstract Solar wind drives magnetospheric dynamics through coupling with the geospace system at the magnetopause. While upstream fluctuations correlate with geomagnetic activity, their impact on the magnetopause energy transfer is an open question. In this study, we examine three‐dimensional global magnetospheric simulations using the Geospace configuration of the Space Weather Modeling Framework. We examine the effects of solar wind fluctuations during a substorm event by running the model with four different driving conditions that vary in fluctuation frequency spectrum. We demonstrate that upstream fluctuations intensify the energy exchange at the magnetopause increasing both energy flux into and out of the system. The increased energy input is reflected in ground magnetic indices. Moreover, the fluctuations impact the magnetopause dynamics by regulating the energy exchange between the polar caps and lobes and energy transport within the magnetotail neutral sheet.
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Stormtime Energetics: Energy Transport Across the Magnetopause in a Global MHD Simulation
Coupling between the solar wind and magnetosphere can be expressed in terms of energy transfer through the separating boundary known as the magnetopause. Geospace simulation is performed using the Space Weather Modeling Framework (SWMF) of a multi-ICME impact event on February 18–20, 2014 in order to study the energy transfer through the magnetopause during storm conditions. The magnetopause boundary is identified using a modified plasma β and fully closed field line criteria to a downstream distance of −20 R e . Observations from Geotail, Themis, and Cluster are used as well as the Shue 1998 model to verify the simulation field data results and magnetopause boundary location. Once the boundary is identified, energy transfer is calculated in terms of total energy flux K , Poynting flux S , and hydrodynamic flux H . Surface motion effects are considered and the regional distribution of energy transfer on the magnetopause surface is explored in terms of dayside X > 0 , flank X < 0 , and tail cross section X = X m i n regions. It is found that total integrated energy flux over the boundary is nearly balanced between injection and escape, and flank contributions dominate the Poynting flux injection. Poynting flux dominates net energy input, while hydrodynamic flux dominates energy output. Surface fluctuations contribute significantly to net energy transfer and comparison with the Shue model reveals varying levels of cylindrical asymmetry in the magnetopause flank throughout the event. Finally existing energy coupling proxies such as the Akasofu ϵ parameter and Newell coupling function are compared with the energy transfer results.
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- Award ID(s):
- 2033563
- PAR ID:
- 10353885
- Date Published:
- Journal Name:
- Frontiers in Astronomy and Space Sciences
- Volume:
- 8
- ISSN:
- 2296-987X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fspas.2021.756732
