Japan Geoscience Union Meeting 2015

Presentation information


Symbol A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS21] Atmospheric Chemistry

Thu. May 28, 2015 11:00 AM - 12:45 PM 201B (2F)

Convener:*Yousuke Sawa(Oceanography and Geochemistry Research Department, Meteorological Research Institute), Nobuyuki Takegawa(Graduate School of Science and Engineering, Tokyo Metropolitan University), Yugo Kanaya(Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology), Kenshi Takahashi(Research Institute for Sustainable Humanosphere, Kyoto University), Hiroshi Tanimoto(National Institute for Environmental Studies), Chair:Motoki Sasakawa(National Institute for Environmental Studies)

12:15 PM - 12:30 PM

[AAS21-18] Relationship between interannual variation in the changing rate of APO trend at Cape Ochi-ishi and PDO

*Yasunori TOHJIMA1, Hitoshi MUKAI1, Toshinobu MACHIDA1, Yukio TERAO1 (1.National Institute for Environmental Studies)

Keywords:APO, atmospheric oxygen, PDO, atmospheric CO2, air-sea gas exchange

Since atmospheric potential oxygen (APO=O2+1.1xCO2) mainly reflects the air-sea gas exchange of O2 and CO2 by definition, the spatio-temporal variations in APO are expected to constrain the ocean biogeochemical process and dynamics. Here we examine the relationship between temporal variations in APO trend observed at Cape Ochi-ishi (COI; 43.2oN, 145.5oE) and the Pacific Decadal Oscillation (PDO) index to investigate the causes for the inter-annual variations in the APO trend. The PDO is a long-term Pacific climate variability, having two extreme phases which is classified by basin-scale patterns of the sea surface temperature (SST) anomaly. When the SST anomalies are cool in the northern North Pacific and warm in the tropical Pacific, the PDO index has positive value. And the opposite pattern of the SST anomalies correspond to the negative PDO index. The cool SST enhances the ocean vertical ventilation which brings deeper waters with depleted O2 to the surface, causing the O2 ingassing. The cool SST also enhances the ingassing flux by increasing gas solubility. To the contrary, the enhanced ocean vertical ventilation brings the subsurface nutrients to the surface, enhancing the O2 outgassing through the increase in the ocean primary production. Thus, the correlation analysis between the changing rate of the APO trend (dAPO/dt) at COI and the PDO index would allow us to investigate how the SST anomaly in the northern North Pacific affect the air-sea gas exchanges. Unfortunately, there is no significant correlation between dAPO/dt and the POD index. However, when dAPO/dt and the PDO index are decomposed into the middle (0.3