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

Authors: ISHIJIMA, K.; NAKAZAWA, T.; AOKI, S.

Source: Tellus B, Volume 61, Number 2, April 2009 , pp. 408-415(8)

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Abstract:

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.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1600-0889.2008.00406.x

Affiliations: 1: Center for Atmospheric and Oceanic Studies, Tohoku University, Sendai 980-8578, Japan

Publication date: 2009-04-01