Variations of atmospheric nitrous oxide concentration in the northern and western Pacific

K. Ishijima, T. Nakazawa, S. Aoki

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27 Citations (Scopus)


Atmospheric N2O concentration was observed in the Pacific for the period 1991-2006, using commercial container ships sailing between Japan and North America and between Japan and Australia or New Zealand. The N2O concentration showed a secular increase and interannual variations at all sampling locations, but a seasonal cycle was detectable only at northern high latitudes. The annual mean N2O concentration showed little longitudinal variations (within ± 0.3 ppb) in the northern Pacific, but showed a clear north-south gradient of about 0.8 ppb, with higher values in the Northern Hemisphere. The annual mean N2O was also characterized by especially high values at 30°N due to strong local N2O emissions and by a steep latitudinal decrease from the equator to 20°S due to the suppression of interhemispheric exchange of air by the South Pacific Convergence Zone. The N2O growth rate showed an interannual variation with a period of about 3 yr (high-values in 1999 and 2000), with a delayed eastward and poleward phase propagation in the northern and western Pacific, respectively. The interannual variations of the N2O growth rate and soil water showed a good correlation, suggesting that the N2O emission from soils have an important causative role in the atmospheric N2O variation.

Original languageEnglish
Pages (from-to)408-415
Number of pages8
JournalTellus, Series B: Chemical and Physical Meteorology
Volume61 B
Issue number2
Publication statusPublished - 2009
Externally publishedYes

ASJC Scopus subject areas

  • Atmospheric Science


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