SCOS97 - NARSTO - Aerosol Program

This page last reviewed June 1, 2000


View from Mt. Wilson


Conceptual Framework for the SCOS97 Aerosol Study

The purpose of the SCOS97 aerosol project is to take advantage of the enhanced monitoring support available during the SCOS97-NARSTO ozone study period to deploy both advanced surface measurement equipment and airborne aerosol analyzers to develop a three-dimensional picture of the generation and evolution of typical late summer aerosols in Southern California. The participants have various complementary interests, both regulatory and scientific, in understanding:

  • Relationships between motor vehicle emissions and ambient aerosols,
  • Processes of secondary aerosol formation, especially organics and ammonium nitrate,
  • How ozone control strategies may influence aerosol formation,
  • Contributions of various sources, particularly heavy duty diesels, to both the primary and secondary particle burdens in the atmosphere, and
  • Movement of aerosol-laden air masses, and how they evolve as they pass over the SoCAB landscape and interact with the various gas and particle sources distributed across the basin.

In addition, these experiments provide opportunities to refine some of the research tools available for aerosol analysis; among these R&D goals are:

  • Develop quantitative calibrations for capture and detection efficiencies for the ATOFMS,
  • Refine and extend the library of organic aerosol source "profiles."
  • Improve aerosol models and source allocation schemes.

The major tasks of this effort are:

  • Conduct advanced surface measurements, including Aerosol Time of Flight Mass Spectrometry (ATOFMS) single-particle analysis, impactor sampling for size-resolved organic chemistry, and aerosol sizing for mass distributions; these data will then be used to characterize aerosols in coastal, mid-basin, and interior locations in Southern California.
  • Use aircraft to measure aerosol size and concentration and sample aerosols and precursors high in the mixed layer.
  • Combine aerosol measurements with gaseous pollutant data collected by the SCOS97-NARSTO ozone program to investigate the dynamics of secondary organic aerosol formation.
  • Use real-time ammonia, nitric acid, and aerosol nitrate measurements to observe the concentration-humidity-temperature phase dependence among ammonia, nitric acid, and nitrate aerosols in ambient air.
  • Develop speciated hydrocarbon data to distinguish between gasoline and diesel vehicle exhaust contributions to ambient aerosol.
  • Apply chemical species data from previous source sampling and current field studies to allocate primary organic and inorganic aerosol components to their sources in the SoCAB.
  • Use meteorological and statistical analyses to identify temporal and spatial distributions of source areas for precursors to secondary aerosols.
Aerosol and Radiation Measurement Sites

View a map of the Southern California area under study and the associated data collection sites.