Rossby number

The Rossby number (Ro) is a dimensionless number consisting of the ratio of inertial (e.g., centrifugal) force to Coriolis force. It is used in modeling atmosphere and ocean dynamics and has been used in relation to circumstellar disks. It is defined as:

Ro = U / Lf

• U - characteristic velocity scale.
• L - characteristic length scale.
• f = 2 Ω sin φ - the Coriolis frequency where Ω is the angular frequency of rotation and φ is the latitude.

The convective Rossby number, of interest in the study of convection in stars and planets and the resulting dynamos, is the ratio of a buoyancy force to the Coriolis force.