Upper Limit for NH3in the Stratosphere of Jupiter 16 and 21 Weeks after the SL9 Collision

Abstract

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. Residual stratospheric ammonia was searched for in emission at 930.76 cm−1over the longitudes corresponding to the remnants of the D/G/R/S impact sites. We believe a small amount of ammonia may have been detected in November, but report an upper limit for both dates. The constant 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 × 10−10. This upper limit decreased to ≤2.3 ± 3.0 × 10−10on December 14. These values are equivalent to upper limits of 1.9 ± 1.2 × 10−10on November 8 and ≤1.2 ± 1.5 × 10−10on December 14 if we adopt a constant volume mixing ratio above a base at 100 mbar. We also searched, without success, for stratospheric ammonia on November 9 over the K/W and L impact site remnants. Our upper limits place stronger constraints on the stratospheric ammonia lifetimes and photochemical depletion models.