1. Radiative Thermal Conductivity of the Lower Mantle Emma Rainey Abby Kavner Laurent Pilon

2. Core Mantle Q CMB Lay et al., 2008 Lower Mantle Thermal Conductivity Better constraints on k mantle needed

3. Heat Conduction Mechanisms Two mechanisms likely control heat flow in lower mantle thermal boundary layer Relative importance not well-known Lattice VibrationsRadiation http://quantum-sidsen.blogspot.com/ Courtesy of B. Greenhagen

4. Heat Conduction Mechanisms Two mechanisms likely control heat flow in lower mantle thermal boundary layer Relative importance not well-known Lattice VibrationsRadiation http://quantum-sidsen.blogspot.com/ Courtesy of B. Greenhagen

5. Diffusive Radiative Heat Transfer k rad depends on two optical properties: – Index of refraction (n ) – Absorption coefficient (  ) Grain size (10 -3 m) Photon absorption length (10 -4 m)  T across grain < 10 -4 K Thermal boundary layer (10 5 m) Phonon scattering length (10 -9 m) Mantle Scales

6. Mantle Index of Refraction Model Dominant high P/T effect on n expected to be from density n scales linearly with density for minerals  n  1.8 – 2.2 in lower mantle n = 1.05 + 0.188  Anderson and Schreiber, 1965 density Refractive index

7. High-Pressure Absorption Coefficient of (Mg,Fe)SiO 3 Perovskite Goncharov et al., 2008 Keppler et al., 2008 pressure

8. k rad (T) of Major Lower Mantle Phases Perovskite P P Keppler et al. Goncharov et al.

9. k rad (T) of Major Lower Mantle Phases Perovskite P P P P Keppler et al. Goncharov et al. 6% Fe 15% Fe 25% Fe Ferropericlase (Mg,Fe)O absorption coefficients from Goncharov et al., 2006 and 2009 P

10. k rad vs. Mantle Depth Perovskite (Keppler et al.) Perovskite (Goncharov et al.) Ferropericlase

11. Composite Mantle k rad Data from Goncharov et al. Data from Keppler et al. Composite mantle: 80% Pv + 20% Fp q Series Parallel q

12. Summary k rad at CMB  1-4 W/m·K Sensitivity of k rad to mantle properties: Iron content has large effect compared to temperature Individual phases and phase configuration have significant effect Calculated k rad is upper bound Neglected scattering and minor impurities

13. BACKUPS

14. Index of Refraction and Temperature Profiles