Theoretical models of nonthermal processes in the atmospheres of Venus, Earth and Mars
department or school: Science, Faculty of
department or school: Earth, Ocean and Atmospheric Sciences, Department of
data provider: DSpace
degree campus: UBCV
creator: Arkos, Gregory G
issued: 2009-04-07T16:55:07Z
issued: 1997
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: The present state of planetary exospheres is determined largely by satellite and ground based observations which are predominantly measurements of the emissions of exospheric constituents. Such observations are responsible for the growing recognition of the importance of nonthermal collisional processes in determining the distribution and escape of species in planetary exospheres. Nonthermal processes provide an important enhanced escape mechanism for lighter species such as hydrogen. They may also make escape possible for heavier species, such as oxygen, nitrogen and carbon, for which thermal escape is very small. Nonthermal processes have been employed in order to understand discrepancies in the terrestrial helium budget. They have also been used to reconcile discrepancies between observed and calculated escape fluxes for hydrogen on Earth. Nonthermal processes have also been utilized to explain features observed in the exospheres of other planets. These include the measured deuterium-to-hydrogen ratio on Venus and the extended hot oxygen corona on Mars. Given the importance of nonthermal processes it is clear that exospheric conditions are determined to a large extent by collisional processes and that the collisionless model must be reconsidered. The formation of translationally energetic (or hot) oxygen coronae via the nonthermal process of dissociative recombination of 0₂⁺ in the atmospheres of Venus and Mars is examined using both hydrodynamic and kinetic theory approaches. Of interest is the distribution of hot oxygen at altitude resulting from production and transport from lower altitudes. It is found that an extended hot oxygen corona can be predicted from either approach, although the magnitude and extent of the predicted coronae vary significantly. Product velocity distribution functions describing the rate of production of hot atoms for the atomic systems H-H+, D-H-f, O-H, and O-D are calculated for a variety of nonthermal processes, including direct-ela…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/6856
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note: T H E O R E T I C A L MODELS OF N O N T H E R M A L PROCESSES IN T H E A T M O S P H E R E S OF V E N U S , E A R T H A N D M A R S By Gregory G. Arkos B.Sc. Hons. (Geophysics), University of Manitoba, 1990. A T H E S I S S U B M I T T E D IN P A R T I A L F U L F I L L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F D O C T O R O F P H I L O S O P H Y in T H E F A C U L T Y O F G R A D U A T E S T U D I E S D E P A R T M E N T O F E A R T H A N D O C E A N S C I E N C E S ( G E O P H Y S I C S ) We accept this thesis as conforming to the required standard T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A August 1997 © Gregory G. Arkos, 1997 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Earth and Ocean Sciences (Geophysics) The University of British Columbia 2219 Main Mal l Vancouver, B C , Canada V6T 1Z4 Date: August, 1997. Abstract The present state of planetary exospheres is determined largely by satellite and ground based observations which are predominantly measurements of the emissions of exospheric constituents. Such observations are responsible for the growing recognition of the impor-tance of nonthermal collisional processes in determining the distribution and escape of species in planetary exospheres. Nonthermal processes provide an important enhanced escape mechanism for lighter species such as hydrogen. They may also make escape pos-sible for heavier species, such as oxygen, nitrogen and carbon, for which thermal escape is very small. Nonthermal proces…
has type: Thesis/Dissertation
date issued: 1997-11
is shown at: 10.14288/1.0053469
language: eng
degree discipline: Geophysics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/6856