1. IMPROVE Optical data During the Asian Dust Storm 2001: First Look Bret Schichtel NPS/CIRANPS/CIRA, Fort Collins, CO Schichtel@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.ARSIMPROVE ARS provide the Level 1 QA’ed 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.