Centre for Atmospheric Chemistry

We operate two sites in the TCCON and NDACC networks at the university campus in Wollongong and at Darwin Airport. Each consists of a high resolution Fourier Transform Spectrometer for mid- and/or near-IR spectra (Bruker IFS125), including solar tracker coupled to FTS.

We also operate two portable low resolution solar spectrometers, with trackers, for mobile measurements of total column amounts of trace gases.

Contact: Prof David Griffith

Over the past 10 years we have developed an FTIR-based trace gas analyser for high precision, high accuracy analysis of CO₂, CH₄, CO, N₂O and d¹³C in CO₂ in air. We operate several such instruments for clean and urban air monitoring and combined with auxiliary equipment for flux and exchange measurements:

• soil chambers
• micrometeorological equipment
• water equilibrator for flux measurements from water surfaces
• ozone, NO_x analysers

The FTIR analyser has been commercialised and is available from Ecotech Pty Ltd.

CAC has developed an open path FTIR (OP-FTIR) spectrometer to measure gas emission rates from nearby sources. The OP-FTIR spectrometer measures the gas concentration in the atmosphere over an extended path, typically up to 130 m. While the instrument has been developed by CAC to measure agricultural emissions and fire emissions, the system can be used to measure the concentration of multiple infra-red active gases in the atmosphere including for example boundary emissions from industries and fugitive emissions from pipelines or gas and coal fields.

The heart of the OP-FTIR design is a Bruker infra-red spectrometer and a modified Schmidt-Cassegrain telescope which expands and projects the infra-red beam to a distant retro-reflector. The reflector returns the beam to a mechanically cooled MCT detector at the spectrometer. The instrument is mounted onto a heavy duty tripod via an Automated Instrument Mount (AIM) that allows the instrument’s orientation to be alternated between up to 6 reflectors. The system operates continuously under the control of software written by CAC. The concentration of the target gas is analysed in real-time using the MALT analysis program.

In typical operation of the OP-FTIR system, the measurement path is located downwind from the gas source, for example a fire or livestock, and perpendicular to the predominant wind direction, with the gas carried from the source into the measurement path by the wind.

Contacts: Dr Frances Phillips, Prof David Griffith

We use the GEOS-Chem global three-dimensional chemical transport model and the STILT particle dispersion model to interpret observations from a variety of platforms and better understand the chemical composition of the atmosphere, with particular focus on Australia and the Southern Hemisphere. For more information, see our Modelling and Analysis Research.

Contact: Dr Jenny Fisher

The FTIR trace gas analyser is manufactured, supplied and supported as the Spectronus trace gas and isotope analyser by Australian company Ecotech Pty Ltd under license to UOW. The analyser has been sold internationally in Europe, USA, China, Korea and other countries as well as Australia. More information is available from Ecotech.

AIM has been designed and built by the CAC in collaboration with Illawarra Automation and Control (IAAC Pty. Ltd., Unanderra, NSW). AIM has been developed to mount our Open Path FTIR onto a heavy duty tripod to allow alignment of the instrument to multiple distant mirrors. Software allows for continuous measurements of the multiple measurement paths allowing a higher level of information capture. Although AIM has been designed for our Open Path Instruments, it would be suitable for any application requiring computer control of the orientation of an instrument to multiple targets with a high degree of repeatability.

The AIM is capable of holding instrumentation up to 45 kg in weight. Movement is 350 degrees in the horizontal and +/-15 degrees in the azimuth. Movement resolution is 1mm @ 100m using the pre-set step interval. The AIM unit is controlled through an interface box using in house written software on a PC, either as standalone software or integrated to the software controlling our open path FTIR. The software provides the ability to align the instrument to up to 6 measurement positions plus home position. The AIM unit weighs~15 kg, operates on 240 V and a power consumption of ~500W.

Extensive testing and field deployment have proven the systems pointing accuracy and repeatability. A unit has been sold to Alberta University in Canada and has received very positive feedback about its performance.

AIM is a commercial enterprise between CAC and IAAC. For further information about AIM please contact Travis Naylor, Graham Kettlewell, Dr Frances Phillips, or Prof David Griffith.

The Greenhouse Gas Measurement (GGM) instrument was developed under the Australian Space Research Programme. This project consisted of a consortium of University, Government, and a private company to develop a novel, terrestrial instrument to autonomously measure carbon dioxide and other greenhouse gases in the atmosphere. Work continues at Wollongong to characterise low-resolution FTIR spectrometers, the Bruker Cube and Bruker EM27/Sun. For more information, contact Nicholas Jones.

CAC has supplied the open path analyser to several research groups in Australia and Canada. A commercial instrument based on the CAC design is offered by Bruker Optics, Germany.