Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

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

[A-OS16] Chemical and Biological Oceanography

Mon. May 27, 2019 3:30 PM - 5:00 PM 303 (3F)

convener:Namiha Yamada(National Institute of Advanced Industrial Science and Technology), Sayaka Yasunaka(Japan Agency for Marine-Earth Science and Technology), Hiroaki Saito(Atmosphere and Ocean Research Institute, The University of Tokyo), Chairperson:Tsuneo Ono(Japan Fisheries Research and Education Agency), Naohiro Kosugi(気象研究所)

3:45 PM - 4:00 PM

[AOS16-02] Seasonal variations of oceanic CO2 disequilibrium and anthropogenic CO2 in the subarctic North Pacific

*Bofeng Li1, Shukuta Satori1, Kasai Hiromi2, Hiroshi Kuroda2, Taniuchi Yukiko2, Daisuke Hasegawa3, Yutaka Watanabe1 (1.Hokkaido University, 2.Hokkaido National Fisheries Research Institute, Japan Fisheries and Education Research , 3.Tohoku National Fisheries Research Institute, Japan Fisheries and Education Research )

Keywords:Air-sea CO2 disequilibrium, Anthropogenic CO2, Subarctic North Pacific

Assuming that the CO2 above the surface mixed layer depth (MLD) mixes very well with air, we used a simple and new method to estimate air-sea CO2 disequilibrium value at the MLD (Cdiseq) as follow [Li et al., 2019];

Cdiseq = CMLD – Csat, MLD – Csoft, MLD – Ccarb, MLD

where CMLD is the observed dissolved inorganic carbon (DIC); Csat, MLD is saturated DIC; Csoft, MLD is derived from the remineralization of organic matter; Ccarb, MLD is derived from the dissolution of CaCO3 in the MLD. We collected the DIC and total alkalinity (TA) samples in the subarctic North Pacific in four seasons, and measured all the DIC and TA by using semi-closed cell simultaneous method [Li et al., 2016].

Cdiseq in this region changed from –38.29 to −56.93 μmol kg-1 in wintertime and from −9.65 to 1.02 μmol kg-1 summertime, indicating a strong seasonal change in Cdiseq. Appling these values of Cdiseq to the approach for estimating Cant in this region, we also found a strong seasonal variation in Cant.