NOAA logo National Oceanic and Atmospheric Administration (NOAA),
Earth System Research Laboratory (ESRL)

What does this program measure?

The Mauna Loa Observatory CATS (Chromatograph for Atmospheric Trace Species) CATS program measures the following, where 'ppt' is parts-per-trillion, and 'ppb' is parts-per-billion.

Category Chemical Chemical Formula Units
Chlorofluorocarbons Trichloro(mono)fluoromethane CFC-11 (CCl3F) ppt
Chlorofluorocarbons Dichlorodifluoromethane CFC-12 (CCl2F2) ppt
Chlorofluorocarbons Trichlorotrifluoroethane CFC-113
Hydrochlorofluorocarbons Chlorodifluoromethane HCFC-22 (CHClF2) ppt
Methyl Halides Chloroform CHCl3 ppt
Methyl Halides Methyl Bromide CH3Br ppt
Chlorinated Solvents Carbon Tetrachloride CCl4 ppt
Chlorinated Solvents Halon-1211 CBrClF2 ppt
Chlorinated Solvents Methyl Chloride CH3Cl ppt
Other Measurements Nitrous Oxide N2O ppb
Other Measurements Methyl Chloroform CH3CCl3 ppt
Other Measurements Carbonyl Sulfide COS ppt

How does this program work?

Electron Capture Detection-Gas Chromatography is done continuously at MLO.

Why is this research important?

All of these gases are greenhouse gases. Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), methyl halides (CH3Br and CH3Cl), and N2O deplete stratospheric ozone. Chlorinated solvents are involved in regional air quality.

Are there any trends in the data?

CFCs, CH3CCl3, CH3Br, and CCl4 are decreasing because of the Montreal Protocol. N2O, HCFCs, and HFCs are increasing.

How does this program fit into the big picture?

What is it's role in global climate change?

All of these gases are greenhouse gases to a certain degree.

Comments and References

  • Butler , J.H., J.W. Elkins, B.D. Hall, S.O. Cummings, and S.A. Montzka, A decrease in the growth rates of atmospheric halon concentrations, Nature, 359, 403-405, 1992.
  • Butler, J.H., J.W. Elkins, T.M. Thompson, and K.B. Egan, Tropospheric and dissolved N 2O of the west Pacific and east Indian Oceans during the El Niño-Southern Oscillation event of 1987, J. Geophys. Res. , 94 (D12), 14865-14877, 1989.
  • Dlugokencky, E.J., T. J. Conway, P. P. Tans, S. A. Montzka, and J. W. Elkins, Recent trends in greenhouse gases, in Sixth Symposium on Global Change Studies, pp. 202-204, 1995.
  • Elkins, J.W., T.M. Thompson, T.H. Swanson, J.H. Butler, B.D. Hall, S.O. Cummings, D.A. Fisher, and A.G. Raffo, Decrease in the growth rates of atmospheric chlorofluorocarbons 11 and 12, Nature, 364 (August 26, 1993), 780-783, 1993.
  • Montzka, S.A., J.H. Butler, R.C. Myers, T.M. Thompson, T.H. Swanson, A.D. Clarke, L.T. Lock, J.W. Elkins, Decline in the tropospheric abundance of halogen from halocarbons: Implications for stratospheric ozone depletion., Science, 272, 1318-1322, 1996.
Lead Investigator(s):

James W. Elkins
303-497-6224 Geoffrey S. Dutton

MLO Contact(s):

Aidan Colton
808-933-6965 (x233)
Paul Fukumura
808-933-6965 (x223)

Web Site(s)

Date Started


Related Programs

Halocarbon Flasks
Cooperative Global Air Sampling
Greenhouse Gases

Stealth Gas Chromatograph
Stealth GC Gas Tank System
Calibration tanks