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Adv. Space Res. Vol.12, No.11, pp.(l1)11--(1 1)18, 1992 0273-1177192 $15.00 Printed in Great Britain. All rights r~erved. Copyright 1992 COSPAR
 

Summary: Adv. Space Res. Vol.12, No.11, pp.(l1)11--(1 1)18, 1992 0273-1177192 $15.00
Printed in Great Britain. All rights r~erved. Copyright 1992 COSPAR
HYDROCARBONS AND EDDYMIXING IN
NEPTUNE'S ATMOSPHERE
S. K. Atreya
Department ofAtmospheric, Oceanic and Space Sciences, The University ofMichigan,
2455 HaywardAvenue, Ann Arbor, M148109-2143, U.S.A.
ABSTRACT
The most recent analysis of the Voyager ultraviolet solar occultation observations at Neptune indicates a
methane mixing ratio 1-10 times above saturation in the lower stratosphere, unlike the value of 500-1000
times saturation which was suggested just before the encounter of Voyager with Neptune. The acetylene
mixing ratio in the 0.1 mb region is found to be (6 - 8) x 10-8, which is approximately a factor of 3 lower
than thevalue reported in our Voyager/Science paper. The eddy diffusion coefficient at thehomopause, (1 -
3) x l0~cm2 s~,is found to be more like that on Saturn than Uranus. The new results on CH4, C2H2
andK have strong implications for the stratospheric temperatures, now warmer, and the sourceof heating.
Furthermore, thepre-Voyager models of thehydrocarbon hazesneedtobe revisedin view of thenew model
atmosphere.
Hydrocarbons were detected in Neptune's atmosphere by the Ultraviolet Spectrometer, UVS /1/, and the
Infrared Spectrometer, IRIS /2/, on Voyager 2. The UVS measurements rely on precise monitoring of the
solar flux in the 500-1700A region as the sun `sets' and `rises' in Neptune's atmosphere -- the occultation

  

Source: Atreya, Sushil - Department of Atmospheric, Oceanic and Space Science, University of Michigan

 

Collections: Physics