Group E: Mixingaka “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 mixing2. Determine whether factors that produce layered structures

influence mixing3. 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 fields2. Compare with rates of mixing of passive tracers3. Examine effect of property change in lower mantle

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).

QuickTime™ and a decompressor

are needed to see this picture.“Unlayered” model

Similar results from spherical dynamical models and seismic:The power is concentrated in low degrees

and in the boundary layers

QuickTime™ and a decompressor

are needed to see this picture.“Unlayered” model

Unlayered vs. layered

Unlayered 1D line

Layered 1 D line

Where do we go from here?

• Quantitative analysis of the particles… does the mixing depend on wavelength?

• Interpretation for geochemistry

Particles illustrate mixing

“Unlayered” model

“Unlayered” model

“Unlayered” model

“Unlayered” model