| NASA GSFC | |
| School of Electrical and Computer Engineering | |
| Greenbelt, MD 20771 |
Radiative transfer models which have been used to compute Jupiter's millimeter wave emission do not agree well with existing radio astronomical observations (e.g., de Pater and Massie, 1985). This apparent discrepancy has gone largely unexplained due to a lack of laboratory absorption data at these wavelengths coupled with uncertainties in the calibration of millimeter wave observations. Gaseous ammonia (NH3) is the largest source of millimeter wave opacity on Jupiter. Previous laboratory measurements at 7.5- to 9.38-mm were inconclusive as to which theoretical line shape most accurately describes the millimeter absorptivity of NH3 (Joiner et al., 1989). We have made additional laboratory absorption measurements of gaseous ammonia at a shorter wavelength (3.2 mm) where the theoretical line shapes can be better evaluated. We have a mixture consisting of 85.56% hydrogen (H2). 9.37% helium (He), and 5.07% ammonia (NH3). We give revised formalisms for computing their absorption. We have compiled a list of Jupiter's reliable millimeter wavelength observations. We compare our list of observations with synthetic emission spectra utilizing our revised expressions for computing absorption.