National Oceanic and Atmospheric Administration (NOAA),
Earth System Research Laboratory (ESRL)
Atmospheric methane (CH4) is measured in nanomoles per mole or nmole (abbreviated ppb).
Gas chromatography with flame ionization detection is used in this project with the instruments, location and frequency listed below.
|2.5-L glass flask AIRKIT pump unit||2 pair/week||Kumukahi|
|2.5-L glass flasks,MAKS pump unit||1 pair/week||MLO|
|2.5-L evacuated glass flasks||1 pair/week||MLO|
Methane is a greenhouse gas with a global warming potential.
Methane was steadily increasing in the 1980's, it's growth rate slowed in the 1990's, and it has had a near-zero growth rate for the last few years.
Methane produces about 20% of present day greenhouse gas climate forcing. Methane is prduced by fossil fuel production and agriculture.
Direct radiative forcing due to the increase in methane since pre-industrial times is ~0.5 Wm-2
The NOAA ESRL GMD Carbon Cycle-Greenhouse Gases group (CCGG) conducts research to understand the global carbon cycle and its effects on climate. At CCGG measurements are made to determine baseline levels, trends and causes of variability of several atmospheric gases (carbon dioxide, methane and carbon monoxide), that have the potential to affect global climate.
To obtain detailed understanding of the short term as well as long term variations of the greenhouse gases, CCGG makes on-site measurements at the four NOAA/CMDL baseline observatories, which are far from any pollution sources affecting the gases of interest.
Please visit our web site at http://www.esrl.noaa.gov/gmd/ccgg/flask.html
Dlugokencky, E J et al, Atmospheric methane at Mauna Loa and Barrow observatories: Presentation and Analysis of In-Situ Measurements. J. Geophys. Res., 100, 23,103 -23, 113, 1995.
Masarie, K A et al, A Rule-based Expert system for evaluating the quality of long-term, In Situ, Gas Chromatographic Measurements of atmospheric methane, NOAA Tech. Memo. ERL CMDL-3, NOAA Environ. Res. Lab, Boulder, Colorado, 1991.