HIGH-RESOLUTION 10-MICRONMETER SPECTROSCOPY OF AMMONIA AND PHOSPHINE LINES ON JUPITER

High spectral resolution measurements of NH3 and PH3 lines on Jupiter in the 10.5- to 11.2-mu m range are presented, Observations, recorded on January 21-23, 1991, cover the 10 degrees-40 degrees S latitude ran ge and several longitudes including the Great Red Spot (GRS), Informat ion on the temperature in the upper troposphere was retrieved from the continuum radiance at wavelengths around 12.8 and 17.8 Ecm. At all ob served longitudes, the 200-mbar temperature field is minimum at latitu des of 20 degrees-25 degrees S near the location of the South Tropical Zone, in agreement with Voyager infrared retrievals, This minimum tem perature is lower over the GRS than at other longitudes, The ammonia m ixing ratio at similar to 380 mbar is not significantly enhanced over the GRS. The phosphine abundance probed at similar to 580 mbar is also not enhanced (within a precision of 10%), suggesting that this molecu le is not a precursor of the reddish chromophores, The NH3 abundance a t 380 mbar varies highly with latitude and longitude, a possible conse quence of the active jovian meteorology, At the resolution of our obse rvations (similar to 8000 km), the NH3 humidity at this altitude range s between 15 and 100% throughout the available data set. Above the clo ud tops, the NH, mixing ratio in the 240-mbar region reaches a maximum near 15 degrees-18 degrees S and decreases by a factor of similar to 40 at latitudes 30 degrees-35 degrees S. This variation is not correla ted with the 200-mbar temperature. It can be explained by a decrease o f the eddy mixing coefficient near 240 mbar from similar to 4000 to le ss than or equal to 400 cm(2) sec(-1) between the two latitude ranges, The PH3 mixing ratio near 580 mbar lies between 1.7 and 2.6 x 10(-7) in the observed regions. At all longitudes, PH3 varies smoothly with l atitude, decreasing by similar to 30% from 10 degrees to 35 degrees S. This variation may also reflect a decrease in the strength of the edd y mixing near 580 mbar or at deeper levels in the atmosphere. (C) 1998 Academic Press.