In the Upper Hunter Valley
As part of a wider project incorporating ground based aerosol measurements of particulate matter emitted by mining operations, a team from the University of Newcastle, the CSIRO and Sinclair Knight Merz (SKM) built a Light Detection and Ranging (LIDAR) apparatus to demonstrate its capability to analyse atmospheric pollution. LIDAR technology uses lasers in a similar way to RADAR to monitor the atmosphere and is sensitive to particle sizes larger than ~0.5m m diameter, within ranges of 150 to 3000 metres from the LIDAR.
An understanding of the vertical structure of the lower atmosphere is essential to accurately assess the dispersion of air pollutants from surface and secondary sources. Especially important is the height of the atmospheric boundary layer or ‘mixing layer’. The lack of information about variability in the vertical structure of the lower atmosphere hampers predictions of air pollutant dispersion over smaller regions.
LIDAR technology represents an ideal way of assessing the vertical structure of the atmosphere by allowing highly sensitive atmospheric structure measurements over very short time intervals. The LIDAR provides a trace of backscatter from aerosols trapped within various layers, and a repeating pulsed laser can provide thousands of height profile measurements in a few hours.
The completed LIDAR was transported to the NSW Hunter Valley and set up adjacent to the Lemington and Narama coal mines for a period of three months to measure aerosol backscatter. Operating the LIDAR near working coal mines, while simultaneously acquiring aerosol information with more commonly used in situ instruments, such as High Volume Samplers and DustTraks, represented a novel experiment for the region.
The general conclusion from the measurements is that the Upper Hunter atmosphere remains relatively clean despite the aerosol loading of particular events inextricably linked with mining activity.