Numerical simulations of decaying turbulence are conducted with the two-level rotating spherical model and their results are discussed in connection with the properties of two-dimensional (2D) nondivergent turbulence. In small Lamb parameter cases, the evolution of flow field at each level is independent of each other, and has resemblance to that of 2D nondivergent flow. In large Lamb parameter cases, the barotropic mode is dominant. A barotropic zonal band structure and a westward circumpolar vortex are also seen in rapid planetary rotation cases. Energy transfer from the baroclinic to barotropic mode is also discussed. Unlike quasi-geostrophic turbulence, the wavenumbers at which barotropization occurs are shifted to lower ones with an increase of Rossby number even when the Rossby deformation radius remains constant. The energy transfer due to interactions with the divergent motion is downward cascading, while that among vortices only is upward cascading as in 2D turbulence. (C) 2003 Published by The Japan Society of Fluid Mechanics and Elsevier B.V. All rights reserved.