EVIDENCE FOR SUPERSONIC TURBULENCE IN THE UPPER-ATMOSPHERE OF JUPITER

Spectra of the hydrogen Lyman alpha. (Ly-alpha) emission line profiles of the jovian dayglow, obtained by the Goddard High Resolution Spectr ograph on the Hubble Space Telescope, appear complex and variable on t ime scales of a few minutes. Dramatic changes occur in the Ly-alpha bu lge region at low latitudes, where the line profiles exhibit structure s that correspond to supersonic velocities of the order of several to tens of kilometers per second, This behavior, unexpected in a planetar y atmosphere, is evidence for the particularly stormy jovian upper atm osphere, not unlike a star's atmosphere.