The linear instability and nonlinear saturation of electrostatic emission near the lower hybrid frequency is examined for model cold and warm ion ring distributions and auroral zone parameters. In the cold ring case, a single coherent mode near &ohgr;LH evolves, and saturates by ion trapping. In the warm ring case, a discrete spectrum of unstable modes separated by the ion gyrofrequency is generated near and above &ohgr;LH. The latter instability saturates by quasilinear diffusion.