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标题：Methane: Interhemispheric concentration gradient and atmospheric residence time
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作者：Edward W. Mayer ; Donald R. Blake ; Stanley C. Tyler 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：4
页码：1366-1370
DOI：10.1073/pnas.79.4.1366
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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.
关键词：atmospheric OH ; trace composition ; interhemispheric transport ; Amazon basin