Contact: L' Barrie, CENV

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WMO/IUGG Science Assessment of Aerosol Effects on
Precipitation
May 2003 The Fourteenth World Meteorological
Congress (general summary paragraph 3.3.5.4)
noted with concern the new additional evidence,
also presented at the 8th WMO Scientific
Conference on Weather Modification, that was
pointing to an apparent substantial reduction of
the rainfall efficiency of clouds by plumes of
smoke caused by biomass burning (agricultural
practices, forest fires, cooking and heating) and
industrial processes and recommended CAS to
establish an ad hoc group to address this
problem. July 2003 The IUGG Congress recommended
that a body be established to undertake an
international programme of study and assessment
of the rain related effects of biomass burning in
collaboration with WMO and other international
organizations. May 2004 WMO/IUGG Science
Assessment of Aerosol Effects on Precipitation
was initiated. The president of CAS established
an ad hoc International Aerosol Precipitation
Science Assessment Group (IAPSAG).The group and
its tasks are defined on the reverse side of this
handout.
Precipitation change
Links to IUGG, IAMAS, IPCC
Contact L. Barrie, C/ENV Lbarrie_at_wmo.int
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CAS Ad Hoc International Aerosol Precipitation
Science Assessment Group (IAPSAG)

• IAPSAG is tasked to
• Conduct the WMO/IUGG Science Assessment of
  Aerosol Effects on Precipitation in time for
  Fifteenth World Meteorological Congress and the
  IUGG Congress in 2007 as well as the next IPCC
  assessment.
• Address the following topics
• The effects of aerosol pollution, including
  biomass burning, on precipitation
• The climatology of the weather-active aerosol and
  cloud droplets
• The observational system for studying effects of
  weather-active aerosol on clouds and
  precipitation
• Modeling of global, regional and cloud scale
  effects of pollution
• Relevance of cloud seeding experiments.

8/05/04