A major contract designed to improve air quality forecasting has been awarded to QinetiQ by the Department for Environment, Food and Rural Affairs (DEFRA).
The Environment Act of 1995 requires local authorities to inform the public about air quality. The project aims to improve atmospheric dispersion models to enable better air quality forecasting, specifically within urban areas.
The £800,000 project is funded through HM Treasury’s ‘Invest to Save’ programme. QinetiQ leads a team of partners including the Met Office and the Universities of Salford and Essex.
By using lidars (laser radars) to gather accurate 3D wind flow data the team will develop a better understanding of airflow near the earth’s surface, focussing especially on urban meteorology.
A lidar is similar to conventional radar but uses an invisible, eye-safe, laser beam as its source of radiation. The advantage of lidars for monitoring wind flow is that they can make more precise measurements than conventional radars and can probe to greater heights than anemometers placed upon tall masts. In addition, lidars can make measurements in regions of the lower atmosphere above a city that would be inaccessible to either aircraft or tethered balloons.
Lidars work by measuring the Doppler shift of light back scattered from fine particles, such as water vapour and dust suspended within the atmosphere.
The line of sight velocity component of the winds can then be determined because of the motion of these particulates is directly proportional to the wind flow. By sampling at different angles, and combining results from two lidars, a picture of the three dimensional airflow in a scanned region can be assembled.
Such a complete measurement of wind flow within the urban environment has never been undertaken before and requires the upgrading of two pulsed 10-micronM lidars at Salford University and QinetiQ. Computer software is being developed at Essex University to visualise the flow and aid in the interpretation of the collected data.