1. Group E: Mixing aka “Progress towards Chaos” Kari Cooper, UC Davis, Amber Harris, Rhode Island, Stan Hart, Woods Hole, Louise Kellogg, UC Davis, Julie Prytulak, U. Bristol, Elizabeth Vanacore, Rice U. With help from: John Naliboff, UCDavis/U. Michigan, Natarajan Conjeepuram, UC Davis, Sujoy Mukhopadhyay, Harvard, Magali Billen, UCD Goals: 1.Understand the relationship between scales of convection and scales of mixing 2.Determine whether factors that produce layered structures influence mixing 3.Assess the influence of length scales on stirring and mixing Methods: Analyze previously calculated convection models with tracers and variable viscosity 1.Calculate the power spectra for temperature fields 2.Compare with rates of mixing of passive tracers 3.Examine effect of property change in lower mantle

2. The models Temperature and pressure-dependent viscosity 2-D, aspect ratio 10x1 Ra = 1e7 (defined by reference properties) Internal heating (about 2/3) and basal heating (about 1/3) Models run past initial transient before particles introduced Power spectra calculated using Matlab Models previously calculated using ConMan + particles “Unlayered” Model: No discontinuous change in properties across the mid-mantle “Layered” Model: Factor of 5 increase in viscosity & thermal conductivity at the midpoint (depth).

3. “Unlayered” model

4. Similar results from spherical dynamical models and seismic: The power is concentrated in low degrees and in the boundary layers

5. “Unlayered” model

6. Unlayered vs. layered

7. Unlayered 1D line

8. Layered 1 D line

9. Where do we go from here? Quantitative analysis of the particles… does the mixing depend on wavelength? Interpretation for geochemistry

10. Particles illustrate mixing “Unlayered” model