Temperature and para hydrogen gradients on Jupiter observed from the FORCAST camera on SOFIA

Abstract

Jupiter was observed on December 8, 2010 with SOFIA using the FORCAST mid-infrared camera with selected spectral channels in the 5–40 µm region. Although the channels were not optimized for planetary observations, we demonstrate that useful information on latitude gradients of upper tropospheric temperature and the para hydrogen fraction ƒp can be retrieved. Calibration of the data is refined using simultaneous measurements of Callisto, along with a simplified model of Callisto's thermal behavior. In this preliminary study, an inversion algorithm is applied to measurements in three channels to obtain temperature and ƒp as functions of latitude in an atmospheric layer centered near 300 mbar. The results are compared with those previously obtained from Voyager IRIS, Cassini CIRS, and ground-based measurements. The low-latitude minimum in ƒp is found to be significantly displaced northward from the equatorial minimum in temperature, unlike the gradients found in the earlier Voyager and ground-based measurements. Possible explanations for this behavior are explored.