effects of solar energetic particle events on the martian surface and atmosphere f leblanc, da...
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![Page 1: Effects of Solar Energetic Particle Events on the Martian Surface and Atmosphere F Leblanc, DA Brain, JG Luhmann, GT Delory, RA Mewaldt, CM Cohen 2004](https://reader035.vdocuments.us/reader035/viewer/2022062714/56649d4e5503460f94a2e7a3/html5/thumbnails/1.jpg)
Effects ofSolar Energetic Particle Events
on the Martian Surfaceand Atmosphere
F Leblanc, DA Brain, JG Luhmann, GT Delory, RA Mewaldt, CM Cohen
2004 Fall AGU Meeting - Friday 17 December
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Motivation
Record-setting Halloween 2003 Solar Energetic Particle event occurred when Earth and Mars “on same field line”
Protons 1 MeV to 1 GeV
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Mars Global Surveyor - Electron Reflectometer Data
Electron instrument at Mars “contaminated” by energetic particles
Motivation
What effect do SEP events have on the Martian surface and atmosphere?
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Solar Protons at Mars
http://physics.nist.gov/PhysRefData/Star/Text/contents.html
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Solar Protons at Mars
http://physics.nist.gov/PhysRefData/Star/Text/contents.html
g = 3.71 m/s2
P(0) = 6.36 mbarH = 11.1 km
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Solar Protons at Mars
http://physics.nist.gov/PhysRefData/Star/Text/contents.html
these primaries reach surface
g = 3.71 m/s2
P(0) = 6.36 mbarH = 11.1 km
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Shielding by Martian Atmosphere
protonsalphaselectrons
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Martian Atmosphere
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October Eventat Surface
The time integrated GOES event spectrum resembles the SIREST SEP/SPE input spectrum
http://sirest.larc.nasa.gov/
Integrated Event Spectrum SIREST Input SPE Spectrum
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GCRSEP
InputSpectra
OutputSurface Flux
Surface radiation flux from SEPevent exceeds that from GCRsOctober Event
at Surface
neutrons (up and down)
protons
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Do Crustal Fields Matter?
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Effects of Crustal Fields
exobase
Magnetic fields deflect low energy (few MeV) particles
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Deflection of Primary Protons
small deflection at surface for high energy protons
large deflection for lower energy protons(at higher altitudes)
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Effects of Crustal Fields
For low energy particles:Less energy is deposited above crustal sources than in surrounding
areas
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Summary
• The surface radiation from a large SPE can be important compared to the surface radiation from GCRs.
• Crustal fields can have a significant effect on atmospheric energy deposition during a SPE. They do not have a strong effect on SEPs reaching the Martian surface.