THERMAL PROFILES IN THE AURORAL REGIONS OF JUPITER

The temperature structure within the northern auroral region of Jupite r is studied by reanalyzing the Voyager 1/infrared interferometer and radiometer spectrometer (IRIS) spectra. The total measured excess infr ared auroral zone emission (averaged over the IRIS field of view) in t he hydrocarbon bands between 7 and 13 mum is found to be about 208 erg s cm-2 s-1 over an area of about 2 x 10(18) cm2 with a resulting power output of 4 x 10(13) W. In comparison, the total energy deposition by magnetospheric charged particles has been estimated on the basis of U V observations to range between 1 x 10(13) and 4 x 10(13) W over a com parable area. The large amount of radiated energy observed in the infr ared may imply an additional heat source in the auroral regions (possi bly Joule heating). A new set of thermal profiles of Jupiter's high-la titude upper atmosphere has also been derived. These profiles have a l arge temperature enhancement in the upper stratosphere and are constra ined to reproduce the CH4 emission at 7.7 mum. The emission in the oth er hydrocarbon bands (C2H2 and C2H6) is found to depend on the depth t o which the temperature enhancement extends, which further constrains the thermal profiles. This study shows that a large temperature enhanc ement in the upper stratosphere and lower thermosphere can explain the observed excess hydrocarbon emission bands; thus smaller variations i n hydrocarbon abundances (between the high latitudes and the equatoria l and middle latitudes) are required that has been assumed in previous models.