Evaluating Candidate Particles

Work Package 1: Finding the Perfect Particle

This section of the SPICE project is aiming to discover whether any particle other than sulphate is ideally suited for injection into the Stratosphere for the purpose of reducing global temperature while minimising unwanted side-effects. This phenomenon has been observed following major volcanic eruptions e.g. Mt Pinatubo in 1991.

If successful this might temporarily buy time to reduce carbon emissions and potentially prevent the worst effects of human-induced global warming.

Candidate Particles

If successful this might temporarily buy time to reduce carbon emissions and potentially prevent the worst effects of human-induced global warming. The particles SPICE is looking at is as follows:

  • Sulphate/Sulphuric Acid/Sulphur Dioxide
  • Titania (TiO2rutile)
  • Titania (TiO2anatase)
  • Silicon Carbide (SiC)
  • Diamond (C)
  • Dust(either Arizona test dust of NX-illite)
  • Calcium Carbonate
  • Alumina (alpha-Al2O3)
  • Silica (SiO2)
  • Zinc Oxide

Any particles action is goverened by the following characteristics:

  • Size
  • Surface properties
  • Chemical Composition 
  • Refractive Index

An ideal particle would have:

  • Be higly reflective of sunlight
  • Not too absorptive at longer (terrestrial) wavelengths
  • Little or no influence on the reactive chemistry of the stratosphere

Other Key Factors:

  • Lifetime of the particle in the stratosphere
  • Effects on human health
  • Supply/manufacture costs

To better understand the optical and chemical characteristics of the candidate particles we are using the following techniques:

  • AFT CIMS (Aerosol Flow Tube Chemical Ionization Mass Spectrometer)
  • PFTR CIMS (Plug Flow Tubular Reactor Chemical Ionization Mass Spectrometer)
  • AFT-OA (Aerosol Flow Tube Ozone Analyzer)
  • Coated-Wall Flow Tube
  • Dust Aerosol Generator
  • Laser Tweezers/Laser Beam Trap (Raman Spectroscopy)

Work is being undertaken at the Molecular Spectroscopy Facility (MSF) & the Central Laser Facility (CLF) at the Rutherford Appleton Laboratory (RAL) as well as at Bristol, Oxford & Cambridge Universities.