Japan Geoscience Union Meeting 2019

Presentation information

[E] Poster

A (Atmospheric and Hydrospheric Sciences ) » A-OS Ocean Sciences & Ocean Environment

[A-OS09] Ocean Mixing Processes: Impact on Biogeochemistry, Climate and Ecosystem

Sun. May 26, 2019 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Ichiro Yasuda(Atmosphere and Ocean Research Institute, The University of Tokyo), Toshiyuki Hibiya(Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo), Jun Nishioka(Hokkaido University, Institute of low temperature sciences), Shin-ichi Ito(Atmosphere and Ocean Research Institute, The University of Tokyo)

[AOS09-P07] A comparison of ocean deoxygenation between CMIP5 models and an observational dataset

*Yumi Abe1, Shoshiro Minobe1,5, Takamitsu Ito2, Curtis Deutsch3, Matthew C. Long4 (1.Department of Natural History Sciences, Graduate School of Science,Hokkaido University, Sapporo, Japan, 2.School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA, 3.School of Oceanography, University of Washington, Seattle, Washington, USA, 4.Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA, 5.Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan)

Keywords:North Pacific, North Atlantic

Recent studies revealed that the ocean deoxygenation has been accelerating since the 1980s over the global oceans (Schmidtko et al. 2017; Ito et al. 2017), and the observed trend in the last half-century appears to be much larger than the model simulations conducted for CMIP5 (Bopp et al. 2013). This discrepancy is an important issue of the ocean deoxygenation researches as highlighted by a review paper published in the last year (Oschlies et al. 2018).

In order to understand better the relations of oxygen variations between CMIP5 models and observations, we compare oxygen concentration simulated by CMIP5 models and gridded oxygen anomaly dataset used by Ito et al. (2017). For the global oceans, the observed oxygen reduction rate for the historical experiment period appears to be within uncertainty of the models, though this result can be sensitive to the choice of the analysis period associated with the rapid recent oxygen reduction. We also closely examined the two basins that are relatively well sampled, i.e., the North Pacific and the North Atlantic. It is found that the observed North Pacific oxygen reduction is much stronger than the simulated ones, but such a strong reduction of observed oxygen does not occur in the North Atlantic. These results suggest that there are substantial spatio-temporal variations of oxygen concentration on decadal timescales and their mechanism in each basin should be explored in future studies.