Baroclinic driving and accretion disk transport via the Goldreich-Schubert-Fricke instability

Protoplanetary disks are generally sufficiently cold to have substantial parts of their interiors be non-magnetized. These so-called "dead zones" have been believed to be dynamically quiet and not to support any form of accretion disk turbulence. Recent investigations have indicated the possibility that disks with strong mean radial temperature gradients can support instabilities associated with disk-normal gradients of the basic Keplerian shear profile. This process, known as the Goldreich-Schubert-Fricke instability, is the instability of short radial wavelength inertial modes and depends wholly on the presence of vertical gradients of the mean Keplerian (zonal) flow. We perform asymptotic scaling analysis to isolate the physics of the instability in a semi-global context. We report here high resolution fully nonlinear axisymmetric numerical studies of this instability and find a number of features including how, in the nonlinear saturated state, unstable discs become globally distorted, with strong vertical oscillations occuring at all radii due to local instability and characterized by radially propagating corrugation waves. We find that non-axisymmetric numerical experiments are accompanied by significant amounts angular momentum transport.