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Interpreting the seasonal cycles of atmospheric oxygen and carbon dioxide concentrations at American Samoa Observatory
Author(s) -
Manning Andrew C.,
Keeling Ralph F.,
Katz Laura E.,
Paplawsky William J.,
McEvoy Elizabeth M.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl014312
Subject(s) - environmental science , tropics , carbon dioxide in earth's atmosphere , atmospheric sciences , carbon dioxide , seasonality , ozone , climatology , geology , meteorology , geography , ecology , biology
We present seven years of atmospheric O 2 /N 2 ratio and CO 2 concentration data measured from flask samples collected at American Samoa. These data are unusual, exhibiting higher short‐term variability, and seasonal cycles not in phase with other sampling stations. The unique nature of atmospheric data from Samoa has been noted previously from measurements of CO 2 , methyl chloroform, and ozone. With our O 2 data, we observe greater magnitude in the short‐term variability, but, in contrast, no clear seasonal pattern to this variability. This we attribute to significant regional sources and sinks existing for O 2 in both hemispheres, and a dependence on both the latitudinal and altitudinal origins of air masses. We also hypothesize that some samples exhibit a component of “older” air, demonstrating recirculation of air within the tropics. Our findings could be used to help constrain atmospheric transport models which are not well characterized in tropical regions.