Year

2011

Degree Name

Master of Science - Research

Department

School of Chemistry

Abstract

This thesis describes work done in characterizing a number of important atmospheric trace gas species. There are two main components to this thesis. The first describes a 3 year measurement campaign of carbon dioxide, methane, nitrous oxide, carbonyl sulfide, carbon monoxide, nitrogen dioxide, hydrogen cyanide and formaldehyde total column amounts over Wollongong, in New South Wales, Australia (34.4°S, 150.9°E). The measurements were made by the examination of the intensity of characteristic absorption features observed in infrared spectra obtained by ground-based solar spectrometry. Carbon dioxide, nitrous oxide and hydrogen cyanide total column amounts increased over the campaign whilst a decrease was observed for carbon monoxide and formaldehyde. A larger than expected decrease in the carbonyl sulfide total column was also observed.

The second part of the thesis describes the investigation of the above methods suitability as a possible measurement tool for trace gases in the remote marine boundary layer. Spectra were collected at solar zenith angles greater than 90o above the marine horizon on 4 days. Enhanced absorption features were observed for a large number of species and a spectral region for the possible observation of hypochlorous acid was identified. The experimental setup allowed for transmission of some infrared radiation but not enough to generate a sufficient signal to noise ratio for meaningful calculations to be made. Almost all absorption features were partially saturated or had low signal to noise. Despite these problems, some simple changes to the experimental setup may prove this to be a useful method with preliminary calculations indicating high information content for the marine boundary layer in solar spectra observed at zenith angles greater the 88o with signal to noise ratios of 100. The use of narrower optical band filters for the collection of the dawn spectra is recommended in a bid to increase the signal to noise ratio required for meaningful observations of the marine boundary layer to be made.

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