Abstract for presentation at 14th IUAPPA World Congress

Physical, Chemical and Optical Properties of Australian Desert Dust Aerosols

  • Majed Radhi, University of New South Wales, Australia
  • A/Prof Michael Box, University of New South Wales, Australia
  • Dr Ross Mitchell, CSIRO, Australia
  • Dr Melita Keywood, CSIRO, Australia
  • Gail Box, University of New South Wales, Australia
  • Dr Susan Campbell, CSIRO, Australia
  • Dr David French, CSIRO, Australia
  • Dr David Cohen, Australian Nuclear Science and Technology Organisation (ANSTO), Australia

    • Atmospheric aerosols interact with incoming solar radiation and hence modulate the planetary radiation budget. Aerosol scattering reduces the net radiation input by reflecting a fraction of the incoming sunlight back to space, leading to a cooling. On the other hand, aerosol absorption can result in not only a planetary warming, but can also change the atmospheric temperature profile, and hence vertical stability, with potential hydrological consequences.
    Desert dust (mineral aerosol) is one of the major natural aerosol types, as recognized by the IPCC. However, at the time of the Third Assessment it was not possible to even be sure of the sign of desert dust forcing – i.e. warming or cooling. This is because mineral aerosols are mildly absorbing, a consequence of their variable iron content. Unlike many Northern Hemisphere deserts, which are yellow, most Australian dusts are red, indicative of a different mineralogy.
    A field station at Birdsville, SW Queensland, was installed in August 2005 to address this issue. Instrumentation includes a ten-stage MOUDI sampler, which was used to collect size-resolved aerosol samples which were subsequently subjected to ion-beam analysis to determine the elemental composition. Samples were also collected in a (single stage) LowVol sampler. These samples were also sent for IBA as a cross check, and also for electron microscopy to study shape, size, and mineralogy of individual particles. From this data we have constructed a size-resolved refractive index, and used this to determine the key optical parameters.

    Conference Organiser - ICMS Pty Ltd