The CATS instruments have been in continuous operation at the NOAA baseline observatories since 1999. While the CATS instruments measure the same compounds as their predecessor, the Radiatively Important Trace Species (RITS) instruments; these gas chromatographs (GCs) also measure several additional trace gases including carbonyl sulfide (COS), halon-1211 (CBrClF₂), HCFC-22 (CHClF₂), HCFC-142b (CH₃CClF₂) and methyl chloride (CH₃Cl). The CATS GCs are custom built instruments with four separate channels. Each channel is comprised of a pair of separation columns, flow controllers, an air selection valve, and an electron capture detector.

Locations with CATS GCs

• Pt. Barrow, Alaska (BRW)
• Mauna Loa, Hawaii (MLO)
• Niwot Ridge, Colorado (NWR)
• American Samoa (SMO)
• South Pole (SPO)

Documentation

• Introduction (video)
• The CATS computer (video)
• How to edit the logfile (video)
• A CATS pump-board (video)
• Stopping and Restarting
• Regulators, fittings, and tools
• Omega temperature controllers
• Valco Gas Sample Valve (GSV)
• Valco Stream Selection Valve (SSV)