IMPROVE Optical data During the Asian Dust Storm 2001: First Look

1
IMPROVE Optical data During the Asian Dust Storm
2001 First Look

• Bret Schichtel
• NPS/CIRA, Fort Collins, CO
• Schichtel_at_cira.colostate.edu

2
Optical Monitoring Network

• ARS deploys a number of transmissometers and
  nephelometers to measure light extinction and
  scattering, respectively, at Class I areas for
  the IMPROVE program and urban and rural areas for
  regulatory agencies.
• ARS provide the Level 1 QAed data for this first
  look at the impact of the Asian dust on the
  optical environment.

3
Light Extinction Measurement April 8-18
Between April 13-18 there was low RH and the Bext
was 2-4 times the Bext from the preceding week.
4
Light Extinction and Scattering During Dust Event

• Nephelometers underestimate coarse particle
  scattering by as much as 50 due to truncation of
  the forward scattering lobe.
• The large difference between the Transmissometer,
  Bext and Nephelometer, Bsp along with the low RH
  is a good indication that the Asian dust is
  present.