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 Fall AGU Meeting - Friday 17 December
Dec 20, 2015
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
Motivation
Record-setting Halloween 2003 Solar Energetic Particle event occurred when Earth and Mars “on same field line”
Protons 1 MeV to 1 GeV
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?
Solar Protons at Mars
http://physics.nist.gov/PhysRefData/Star/Text/contents.html
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
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
Shielding by Martian Atmosphere
protonsalphaselectrons
Martian Atmosphere
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
GCRSEP
InputSpectra
OutputSurface Flux
Surface radiation flux from SEPevent exceeds that from GCRsOctober Event
at Surface
neutrons (up and down)
protons
Do Crustal Fields Matter?
Effects of Crustal Fields
exobase
Magnetic fields deflect low energy (few MeV) particles
Deflection of Primary Protons
small deflection at surface for high energy protons
large deflection for lower energy protons(at higher altitudes)
Effects of Crustal Fields
For low energy particles:Less energy is deposited above crustal sources than in surrounding
areas
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.