[en] The observations by Kupo et al. of possibly transient S ii forbidden line emission from the Jovian plasmasphere are interpreted using a uniform model with electron collisions as the excitation mechanism. This nebula seems to have been characterized by log₁₀ T/sube/=4.4 +- 0.6 K and log₁₀[n/sube/]=3.5 +- 0.3 cm^-3 at the time of the observations. The time scales for depletion of the plasma energy and its sulfur content are 10⁶.⁰/sup plus-or-minus/⁰/sup .7/ s and 10⁷.⁶/sup plus-or-minus/⁰/sup .3/ s, respectively. Forbidden-line emission from S ii is a sensitive remote probe of the plasma conditions in the Jovian environment