4:45 PM - 5:00 PM
[AAS04-15] Seasonal and interannual variations of the Atmospheric Potential Oxygen over the Western North Pacific observed by using a cargo aircraft C-130H
Keywords:Atmospheric Potential Oxygen (APO), aircraft observation
The Atmospheric Potential Oxygen (APO=O2+1.1xCO2), calculated by using the corrected O2/N2ratio, also showed prominent seasonal cycles, and the amplitude of the mid-tropospheric seasonal APO cycle observed at 25.5°N was found to be 55 and 31 % of those observed at 33.5°N and the surface MNM (Ishidoya et al., 2017), respectively. On the other hand, the corresponding seasonal amplitude of CO2at 25.5°N was found to be 72 and 93 % of those at 33.5°N and the surface MNM, respectively. An atmospheric transport model (Niwa et al., 2017) reproduced general features of the observed seasonal APO and CO2cycles, and its tagged simulation suggested that the mid-tropospheric seasonal APO cycle in the northern low latitudes was reduced significantly by the anti-phase seasonal APO cycle from the southern hemisphere. The observed APO showed interannual variations superimposed on secular downward trends, and the temporal change rates take maxima from the end of 2014 to the beginning of the 2015 at the surface MNM and in the mid-troposphere at 29 – 34 °N. A comparison between the observed and simulated interannual variations of APO suggested that an interannual variation of the atmospheric transport contributed about 30 % of the observed variation.
We thank the staff of Japan Meteorological Agency for their work to collect the air samples onboard a cargo aircraft C-130H. This study was partly supported by the JSPS KAKENHI Grant Number 15H02814, and the Global Environment Research Coordination System from the Ministry of the Environment, Japan.
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