Pitch angle evolution of energetic electrons at geosynchronous orbit during disturbed times
Solar Cycle Dependence of Mass Density and Ion Composition at Geosynchronous Orbit
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Transcript of Solar Cycle Dependence of Mass Density and Ion Composition at Geosynchronous Orbit
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Solar Cycle Dependence of Mass Density and Ion Composition at Geosynchronous Orbit
Richard E. Denton, Dartmouth
Kazue Takahashi, APL
Michelle Thomsen, LANL
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Solar Cycle DependenceMPA ion densityMass density
f10.7 f10.7
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Same But Just on Dayside
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MPA, total, low energy, and high energy – Still Dayside
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Conclusions
• At geosynchronous orbit, the mass density peaks at solar maximum while ion density peaks at solar minimum, the opposite of the expected trend for electron density
• This implies a much higher concentration of O+ at solar maximum.
• VERY preliminary and not quite right: MPA underestimates ion density by a factor of 4 for O+. Assuming a H+/O+ plasma, we can use the average values at solar max and solar min to find nO+/ne = 0.42 and average ion mass M = 7 at solar max, and nO+/ne = 0.08 and M = 2.2 at solar min.