Effects of Solar Energetic Particle Events on the Martian Surface and Atmosphere F Leblanc, DA...

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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
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Transcript of Effects of Solar Energetic Particle Events on the Martian Surface and Atmosphere F Leblanc, DA...

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.

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

Page 2: 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.

Motivation

Record-setting Halloween 2003 Solar Energetic Particle event occurred when Earth and Mars “on same field line”

Protons 1 MeV to 1 GeV

Page 3: 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.

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?

Page 4: 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.

Solar Protons at Mars

http://physics.nist.gov/PhysRefData/Star/Text/contents.html

Page 5: 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.

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

Page 6: 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.

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

Page 7: 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.

Shielding by Martian Atmosphere

protonsalphaselectrons

Page 8: 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.

Martian Atmosphere

Page 9: 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.

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

Page 10: 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.

GCRSEP

InputSpectra

OutputSurface Flux

Surface radiation flux from SEPevent exceeds that from GCRsOctober Event

at Surface

neutrons (up and down)

protons

Page 11: 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.

Do Crustal Fields Matter?

Page 12: 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.

Effects of Crustal Fields

exobase

Magnetic fields deflect low energy (few MeV) particles

Page 13: 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.

Deflection of Primary Protons

small deflection at surface for high energy protons

large deflection for lower energy protons(at higher altitudes)

Page 14: 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.

Effects of Crustal Fields

For low energy particles:Less energy is deposited above crustal sources than in surrounding

areas

Page 15: 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.

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.