CN Column Coordination

Currently all of the aerosol sites have CN counters except IAP (the ARM aircraft).

Column 5 is referred to as CN_control. CN_control is used when the system has been optimized for contamination control. For this configuration, the CN counter (or CPC) is connected to a separate, high-speed inlet.

Column 6 is referred to as CN_ambient. Here the system is configured for ambient sampling. The CN counter takes its sample out of the aerosol sampling line.

The "standard operating procedure" is to put the CN counter in Column 5.   There are, of course, exceptions.

Exceptions

• As of (051205) the following systems place the CN data in Column 6:
  • SGP - Southern Great Plains ARM site
  • CSJ - Cape San Juan, Puerto Rico
• AMF - The CCN is connected to Column 6
• SGP - For data up until May 19, 2004 (Doy 140), there was summed OPC data in Column 5
• AAO and CVI - have a second CN counter in Column 6.

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This document last modified: December 6, 2005