Year

2022

Degree Name

Doctor of Philosophy

Department

School of Earth, Atmospheric and Life Sciences

Abstract

The work presented in this thesis aims to improve our understanding of biogenic and anthropogenic volatile organic compounds (VOCs) over south-east Australia, while evaluating and identifying factors influencing model simulation results in the region. Specifically, this thesis presents three studies.

The first study was aimed at investigating the uncertainties in model simulation results by comparing between the chemical transport models GEOS-Chem and CSIRO-CTM using biogenic VOC emissions from emissions model MEGAN. Five scenarios with different model/emission schemes were compared to understand which factors were driving significant differences in the simulated mole fractions and subsequent chemistry involving VOCs in the atmosphere. Both models have a relatively good performance reproducing measured temporal variation but failed to accurately simulate the magnitude of biogenic VOC mole fractions. Meteorology fields were one of the factors influencing these discrepancies. Both emissions and chemistry are light and temperature dependent and the mole fractions are constrained by the physical mixing of the atmosphere. Both models captured the observed trends of isoprene and monoterpenes but failed to reproduce effects at finer scales. VOC mole fractions and net production of ozone and hydroxyl radical (OH) were highly influenced by the emission scheme selected. Increases of isoprene led to decreases in ozoneby OH titration and consequent isoprene ozonolysis favoured under lower OH conditions.

FoR codes (2008)

0401 ATMOSPHERIC SCIENCES

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.