Contents

1.1 Large Scale Circulation

1.1.1 Mid Latitude Wave Driven Circulation
1.1.2 Transport in the Tropics
1.1.3 The Polar Vortex

1.2 Stratospheric Ozone and Terrestrial Ultraviolet Levels
1.3 Stratospheric Ozone Chemistry

1.3.1 Ozone Production and Chapman's Mechanism
1.3.2 Stratospheric Ozone Depletion
1.3.3 HO_x Chemistry
1.3.4 NO_x Chemistry
1.3.5 Cl_x Chemistry
1.3.6 Reservoir Species
1.3.7 Chemistry in the Polar Vortex

1.4 Use of Fourier Spectrometry for Stratospheric Monitoring

1.4.1 Importance of Height Resolution
1.4.2 Vertical Profile Retrieval
1.4.3 Measurement of Instrument Response

1.5 Outline of Thesis

2.1 Rotational Spectra of Diatomic Molecules

2.1.1 The Rigid Rotator
2.1.2 The Nonrigid Rotator

2.2 Vibration Spectra of Diatomic Molecules

2.2.1 The Harmonic Oscillator
2.2.2 The Anharmonic Oscillator

2.3 Vibration-Rotation Spectra of Diatomic Molecules

The Rotating Oscillator

2.4 Spectra of Other Polyatomic Molecules

2.4.1 Rotational Spectra of Polyatomic Molecules

Linear Molecules
Spherical Top Molecules
Symmetric Top Molecules
Asymmetric Top Molecules

2.4.2 Vibrational Spectra of Polyatomic Molecules
2.4.3 Vibration-Rotation Spectra of Polyatomic Molecules

2.5 Some Other Aspects of Absorption Spectra

2.5.1 Line Strengths and Transition Probabilities
2.5.2 Line Widths
2.5.3 Nuclear Hyperfine Splitting

3.1 Basic Principles of Fourier Transform Spectroscopy
3.2 The Optical Arrangement of the Bruker IFS 120M
3.3 Relevant Aspects of Data Acquisition in the Bruker IFS 120M
3.4 Resolution and Instrumental Factors Affecting it

3.4.1 Effect of Finite Optical Path Difference
3.4.2 Resolution
3.4.3 Field of View

3.5 Phase Error and Correction

4.1 Forward Model

4.1.1 Theory and Approximations
4.1.2 Radiative Transfer
4.1.3 Refraction and Geometry
4.1.4 Vertical Structure
4.1.5 Scattering Processes
4.1.6 Absorption and Emission
4.1.7 Implementation

4.2 Retrieval Scheme
4.3 Effects of Noise
4.4 Effects of Broadening
4.5 Effects of Asymmetry
4.6 Conclusions: Implicationsfor Line Shape Measurements

4.6.1 Broadening
4.6.2 Asymmetry
4.6.3 Noise

Infrared Laser System
5.1 Infrared Laser

5.1.1 Laser Cavity Modes and Cavity Alignment

5.1.1.1 Longitudinal Cavity Modes
5.1.1.2 Off-Axis Cavity Modes

5.2 Thermometry and Power Measurement
5.3 Beam Expansion and Collimation

5.3.1 Reflective Diffuser

5.4 Delivery Optics
5.5 Alignment Procedure

5.5.1 Alignment of theRed Beam
5.5.2 Alignment of the Infrared Beam

5.6 Validation of Infrared Laser Beam Profile

5.6.1 Error Estimates for Beam Profiles

5.7 Conclusions

6.1 Experimental Setup Used for Line Shape Measurements
6.2 Measurements Made at Table Mountain, California
6.3 Measurements Made at Lauder, New Zealand
6.4 Conclusions

7.1 Improper Correction of Phase Error
7.2 Misalignment
7.3 Frequency Drift

7.3.1 Estimation of Laser Frequency Drift
7.3.2 Modelling the Effects of Laser Frequency Drift

7.4 Non-uniform Illumination of the Aperture
7.5 Conclusions

A2.1 Low Pressure Gas Cell
A2.2 Cell Filling Rig
A2.3 Cell Filling Procedure

A3.1 Simulation of the Hyperfine Spectrum of Hydrogen Bromide