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Atmospheric chemistry and transport modeling in the outer solar system

Citation

Lee, Yuan-Tai (2001) Atmospheric chemistry and transport modeling in the outer solar system. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/y7ep-g464. https://resolver.caltech.edu/CaltechTHESIS:01252013-101859233

Abstract

This thesis consists of 1-D and 2-D photochemical dynamical modeling in the upper atmospheres of outer planets. For 1-D modeling, a unified hydrocarbon photochemical model has been studied in Jupiter, Saturn, Uranus, Neptune, and Titan, by comparing with the Voyager observations, and the recent measurements of methyl radicals by ISO in Saturn and Neptune. The CH_3 observation implies a kinetically sensitive test to the measured and estimated hydrocarbon rate constants at low temperatures. We identify the key reactions that control the concentrations of CH_3 in the model, such as the three-body recombination reaction, CH_3 + CH_3 + M → C_(2)H_6 + M, and the recycling reaction H + CH_3 + M →CH_4 + M. The results show reasonable agreement with ISO values. In Chapter 4, the detection of PH_3 in the lower stratosphere and upper troposphere of Jupiter has provided a photochemical-dynamical coupling model to derive the eddy diffusion coefficient in the upper troposphere of Jupiter. Using a two-layers photochemical model with updated photodissociation cross-sections and chemical rate constants for NH_3 and PH_3, we find that the upper tropospheric eddy diffusion coefficient <10^5 cm^2 sec^(-1) and the deeper tropospheric value >10^6 cm^2 sec^(-1) are required to match the derived PH_3 vertical profile by the observation. The best-fit functional form derivation of eddy diffusion coefficient in the upper troposphere of Jupiter above 400 mbar is K = 2.0 x 10^4 (n/2.2 x 10^19)^(-0.5)cm^2 sec^(-1). On the other hand, Chapter 5 demonstrates a dynamical-only 2-D model of C_(2)H_6 providing a complete test for the current 2-D transport models in Jovian lower stratosphere and upper troposphere (270 to 0.1 mbar pressure levels). Different combinations of residual advection, horizontal eddy dispersion, and vertical eddy mixing are examined at different latitudes.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Planetary Science and Astronomy
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Planetary Sciences
Minor Option:Astronomy
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Blake, Geoffrey A. (advisor)
  • Yung, Yuk L. (advisor)
Group:Astronomy Department
Thesis Committee:
  • Ingersoll, Andrew P.
  • Stevenson, David John
  • Blake, Geoffrey A.
  • Murray, Bruce C.
Defense Date:9 August 2000
Record Number:CaltechTHESIS:01252013-101859233
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:01252013-101859233
DOI:10.7907/y7ep-g464
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7438
Collection:CaltechTHESIS
Deposited By: Dan Anguka
Deposited On:25 Jan 2013 19:17
Last Modified:16 Apr 2021 23:21

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