Using LIDAR to measure the atmosphere

  • Supervisors: Prof Geraint Vaughan
    Dr Hugo Ricketts


  • External Supervisors:

  • Contact:

    Prof Geraint Vaughan (geraint.vaughan@manchester.ac.uk)

  • CASE Partner: Yes - Mark Bourn, UK Environment Agency

Application deadline: 3 February 2017

Introduction:

Lidar (light detection and ranging) is a technique whereby laser light is transmitted into the atmosphere, and the back-scattered light detected with a telescope. Our group uses lidars to investigate a number of atmospheric properties - pollution and mixing in the atmospheric boundary layer, measurements of atmospheric gases such as water vapour and ozone, temperature profiles and atmospheric aerosol. We develop our own lidars, use mobile lidars on field campaigns and use lidar data in conjunction with other techniques, particularly radar wind profilers.

At the NERC MST radar site at Capel Dewi near Aberystwyth our group maintains two large fixed lidar systems for measurements throughout the troposphere and stratosphere – one to measure water vapour and aerosols, and another to measure ozone – and a third, mobile, lidar for detailed boundary layer measurements. We are also developing smaller lidars for mobile applications. Our lidars were heavily used for example during the volcanic ash emergency following the eruption of Eyjafjallajökull, where the data helped the Met Office predict the spread of the ash.

 

Project Summary:

The project has a number of strands which can be adapted to suit the aptitude and interest of potential students:

a)    Use of aerosol and Raman lidars to study the long-range transport of forest fire smoke from Canada and Russia to the UK. Each summer, extensive forest fires develop over the boreal forests and under suitable weather conditions the smoke can spread around the hemisphere. The project will examine the dispersion of smoke using measurements from our own lidars and those run by the Met Office, as well as conducting supporting modelling studies.

b)    Pollution measurements using differential absorption lidar. The NCAS ozone-aerosol lidar provides detailed measurements of these quantities which show the intricate relationship between gas phase and particulate pollutants. The project will use the lidar together with other instruments to study the exchange of ozone and particles between the free troposphere and boundary layer. 

c)    Developing new humidity measurements using Raman lidar. The group already has a Raman water vapour lidar at Capel Dewi which was recently upgraded, and is planning to develop a mobile lidar for use on field campaigns. This is a vital measurement for understanding cloud formation in the atmosphere, and in understanding MST radar reflectivity profiles. This project will involve instrument development, field measurements and scientific interpretation.

d)    Examining the variation of night-time temperature profiles over Manchester, using our newly-developed rotational Raman lidar. This project will involve improving the lidar measurements, taking data and examining whether the low-level air over Manchester can become decoupled from the air above during long winter nights, thus causing a build-up of pollution.

Allied to these measurements will be modelling work using a range of meteorological models available under the aegis of the National Centre for Atmospheric Sciences.

References:

G. Vaughan, D. P. Wareing, S. J. Pepler, L. Thomas, V. Mitev.  Atmospheric temperature measurements by rotational Raman scattering. Applied Optics, 32, 2758-64, 1993.          

D. Müller, I. Mattis, U. Wandinger, A. Ansmann, D. Althausen and A. Stohl. Raman lidar observations of aged Siberian and Canadian forest fire smoke in the free troposphere over Germany in 2003: Microphysical particle characterization. J. Geophys. Res., 110, D17201, doi:10.1029/2004JD005756, 2005

D. N. Whiteman Examination of the Traditional Raman Lidar Technique. II. Evaluating the Ratios for Water Vapor and Aerosols. Applied Optics, 42,. 2593-2608, 2003 

Apply Now