[Previous] | [Session 21P] | [Next]
D.P. Sheehan (USD), S.S. Davis (NASA - Ames)
A number of waves and instabilities have been identified as pertinent to the evolution of the protoplanetary nebula, particularly for their roles in mass, angular momentum and energy transport. In the earth's atmosphere, the wave most influential in determining large-scale meteorological phenomena is the planetary Rossby wave (PRW). Given the strong physical similarities between planetary and nebular fluids (e.g., high Reynolds number, low Mach and Rossby numbers, non-zero beta parameter, thin fluids), it is reasonable to consider whether Rossby waves might have similar importance in the nebula. We explore the linear regime of the nebular analog to the PRW: the nebular Rossby wave (NRW). The NRW linear dispersion relation is derived from the momentum and continuity equations, neglecting the self-gravity of the disk. The NRW is found to be dispersive, very low frequency (f-1 >> \tauorbital), and neutrally stable azimuthally. Maximum phase velocities are much less than the sound speed. Possible ramifications of NRW turbulence to disk development will be discussed, especially with regard to the Rhines inverse energy cascade, zonal jet formation, vortices and planetesimal accretion.