UPPER LIMIT FOR NH3 IN THE STRATOSPHERE OF JUPITER 16 AND 21 WEEKS AFTER THE SL9 COLLISION

Spectroscopic observations of Jupiter at thermal-infrared wavelengths were performed on November 8-9 and December 14, 1994, 16 and 21 weeks after the fragments of comet Shoemaker-levy 9 collided with Jupiter, R esidual stratospheric ammonia was searched for in emission at 930.76 c m(-1) over the longitudes corresponding to the remnants of the D/G/R/S impact sites. We believe a small amount of ammonia may have been dete cted in November, but report an upper limit for both dates. The consta nt volume mixing ratio for pressure levels less than 10 mbar that best fits the observation on November 8 is no more than 3.6 +/- 2.4 x 10(- 10). This upper limit decreased to less than or equal to 2.3 +/- 3.0 x 10(-10) on December 14. These values are equivalent to upper limits o f 1.9 +/- 1.2 x 10(-10) on November 8 and less than or equal to 1.2 +/ - 1.5 x 10(-10) on December 14 if we adopt a constant volume mixing ra tio above a base at 100 mbar, We also searched, without success, for s tratospheric ammonia on November 9 over the K/W and L impact site remn ants. Our upper limits place stronger constraints on the stratospheric ammonia lifetimes and photochemical depletion models. (C) 1997 Academ ic Press.