You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Methane: Interhemispheric Concentration Gradient and Atmospheric Residence Time
Edward W. Mayer, Donald R. Blake, Stanley C. Tyler, Yoshihiro Makide, Derek C. Montague and F. Sherwood Rowland
Proceedings of the National Academy of Sciences of the United States of America
Vol. 79, No. 4, [Part 2: Physical Sciences] (Feb. 15, 1982), pp. 1366-1370
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/11858
Page Count: 5
You can always find the topics here!Topics: Methane, Atmospherics, Cerebral hemispheres, Northern hemisphere, Canisters, Geodetic position, Atmospheric lifetime, Atmospheric methane, Gases, Arithmetic mean
Were these topics helpful?See something inaccurate? Let us know!
Select the topics that are inaccurate.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
The ground level concentrations of methane in the atmosphere have been measured to be in the range from 1.45 to 1.62 parts per million by volume (ppmv) of dry air in remote locations between 62 degrees N and 54 degrees S latitudes during the time period from November 1977 to July 1979. The average (± rms) concentration for the northern hemisphere was 1.57± 0.02 ppmv in January 1978 and 1.59± 0.02 in July 1979. The average concentration in the southern hemisphere was lower -1.47± 0.02 in January 1978 and 1.51± 0.01 in July 1979. The ratio of concentrations between the two hemispheres was 1.068± 0.016 in January 1978 and 1.055± 0.013 in July 1979, for an average of 1.06± 0.01. The higher concentrations in the northern hemisphere require either that the sources of methane lie preferentially in the northern hemisphere or that the removal processes operate more rapidly in the southern hemisphere or both. The primary removal process for CH4 is reaction with tropospheric OH radicals and its estimated atmospheric lifetime is 10.5± 1.8 yr. The observed interhemispheric gradient is consistent with this lifetime and preferential release of methane in the northern hemisphere. Measurements taken in the Amazon basin region indicate the presence of a substantial source of methane in that area.
Proceedings of the National Academy of Sciences of the United States of America © 1982 National Academy of Sciences