A COMPARISON OF THE VOYAGER-1 ULTRAVIOLET SPECTROMETER AND PLASMA SCIENCE MEASUREMENTS OF THE IO-PLASMA TORUS

We have developed a sophisticated package (Colorado Io Torus Emissions Package, or CITEP) to simulate emissions from the Io plasma torus, an d have used it to examine the consistency of Voyager in situ and remot e observations, CITEP merges ion composition derived from the ultravio let spectrometer line ratios with measurements of electron densities, electron temperatures, and ion temperatures obtained by the plasma sci ence instrument. The program then predicts the brightness and morpholo gy of torus EUV emissions, We find that the measured brightness is app roximately 2 times larger than the model predicts, When scaled up by t his factor, the morphology of the model radial emission profile is con sistent with the data, but somewhat less sharply peaked at the ribbon location, We examine several possible causes for the brightness discre pancy such as calibration errors, measurement accuracy, inaccuracies o f the model, and torus variability, but find no definitive cause.