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DYCOMS-II Aircraft: C-130 Aerosol LAS-AIR Optical Particle Counter


The LAS-AIR is a commercial instrument (PMS Model 1001) that measured the size distribution of particles between about 0.1 to > 3 microns diameter in 8 size channels. During DYCOMS, the LAS-AIR was one of a number of instruments sampling off the solid diffuser inlet (SDI) which was mounted on the right side of the C-130 aircraft. To dry the sample and prevent coincidence at high concentrations, the LAS-AIR sample stream was diluted with dry nitrogen in a 5:1 ratio (5 parts N2 to 1 part sample). All flow rates were monitored and maintained with constant volume flow controllers. The LAS-AIR samples over a 6 sec interval, so the data rate is once every 6 seconds. Rather than using the manufacturer's calibration, size limits were calibrated using monodisperse ammonium sulfate aerosol. Additional information on the LAS-AIR itself can be found on the PMS website at

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Related projects
Spatial Type point
Frequency < 1 minute
Language English
GCMD Science Keywords Expand keywords

Temporal coverage

Begin datetime 2001-07-13 00:00:00
End datetime 2001-07-28 23:59:59

Spatial coverage

Map data from IBCSO, IBCAO, and Global Topography.

Maximum (North) Latitude: 37.00, Minimum (South) Latitude: 26.00
Minimum (West) Longitude: -127.00, Maximum (East) Longitude: -115.00

Primary point of contact information

Cynthia Twohy <>

Additional contact information


Example citation following ESIP guidelines:

Twohy, C. 2006. DYCOMS-II Aircraft: C-130 Aerosol LAS-AIR Optical Particle Counter. Version 1.0. UCAR/NCAR - Earth Observing Laboratory. Accessed 18 May 2022.

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