Global ConvectionModeling

(where are we heading and how does this impact HMI?)

Mark Miesch

HAO/NCAR, JILA/CU(Sacha Brun, Juri Toomre, Matt Browning, Marc DeRosa, Ben Brown)

Feb, 2006

Objective 1Understand what’s going on in the tachocline and

incorporate it into our models

• Penetrative convection with shear & pumping• Magnetic buoyancy instabilities & flux tube formation• Magneto-shear instabilities (global & local)• Gravity wave generation, propagation & transport• Tachocline confinement• Thermal coupling to convection zone

Objective 2Understand and model the near-surface layers

• Couple to surface convection simulations• Compare with local helioseismic inversions• Near-surface shear layer• Magnetic helicity flux through the photosphere and

conseqences for dynamo action

Objective 33D Dynamo simulations spanning the solar activity cycle which

incorporate convection explicitly

• Narrow the gap with mean-field dynamo models• Subgrid-scale modeling• Coupling to the top & bottom of the CZ (Objectives 1 & 2)

How can HMI help?

• Meridional Circulation– Are flux-transport dynamos on the right track?

• North-South lanes of downflow/horizontal convergence– Are these really the dominant coherent structures at low latitudes?

• Latitudinal entropy/temperature variations– Is the solar rotation really in thermal wind balance?

• Velocity/thermal/magnetic correlations– Invaluable insight into the underlying dynamics

• Non-axisymmetric patterns in flux emergence (esp. m=1)– Indicative of tachocline instabilities?

• Jets & Oscillations– Could reflect instabilities, waves, stratified turbulence, etc.

• Magnetic helicity flux through the photosphere– May regulate dynamo action

How can HMI help?

• Meridional Circulation– Are flux-transport dynamos on the right track?

• North-South lanes of downflow/horizontal convergence– Are these really the dominant coherent structures at low latitudes?

• Latitudinal entropy/temperature variations– Is the solar rotation really in thermal wind balance?

• Velocity/thermal/magnetic correlations– Invaluable insight into the underlying dynamics

• Non-axisymmetric patterns in flux emergence (esp. m=1)– Indicative of tachocline instabilities?

• Jets & Oscillations– Could reflect instabilities, waves, stratified turbulence, etc.

• Magnetic helicity flux through the photosphere– May regulate dynamo action