Slide 9 of 13
- During December 1997, CMDL was participating in a field campaign in Mexico City. Some data (2-hr averages) from November. Black bars denote night-time. Some evidence of upslope-downslope pattern; usually less aerosols (deduced from the scattering values) during the night.
- Mean SSA in Mexico City during this period is < 0.7 (implies lots of soot aerosols).
- Notice the middle period in the graph. Light scattering falls off to low levels. Single scattering albedo is also quite low during this period. Implies that soot aerosols are not being removed as efficiently as the other aerosols, or that a new air mass with extremely high concentrations of absorbing aerosols moved through the area. The relative values of the aerosol light scattering and absorption coefficients suggest that during this period roughly half of the aerosol mass was soot.