JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

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

[A-OS16] [EE] Interdisciplinary ocean studies for global change

Mon. May 22, 2017 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Michio Kawamiya(Japan Agency for Marine-Earth Science and Technology), Shin-ichi Ito(Atmosphere and Ocean Research Institute, The University of Tokyo), Haruko Kurihara(University of the Ryukyus), Shoshiro Minobe(Graduate School of Science, Hokkaido University)

[AOS16-P02] Multi-year estimate of the air-sea CO2 flux in the Arctic with the use of the chlorophyll-a concentration

*Sayaka Yasunaka1, Eko Siswanto1, Are Olsen2,7, Mario Hoppema3, Eiji Watanabe1, Agneta Fransson5, Melissa Chierici4, Akihiko Murata1, Naohiro Kosugi6, Siv Kari Lauvset7, Jeremy Mathis8 (1.Japan Agency for Marine-Earth Science and Technology, 2.University of Bergen, 3.Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 4.Institute of Marine Research, 5.Norwegian Polar Institute, 6.Meteorological Research Institute, 7.Bjerknes Centre for Climate Research, 8.NOAA Arctic Research Program)

Keywords:CO2 flux, Arctic, chlorophyll-a, SOCAT

We examined the relationship between partial pressure of CO2 in the surface water (pCO2w) and chlorophyll-a concentration (Chl-a) in the Arctic. The relationship between pCO2w and Chl-a is negative where Chl-a < 1 mg m-3, but there is no significant relationship where Chl-a > 1 mg m-3. In the Greenland/Norwegian Seas, a relationship between pCO2w and Chl-a is strongly negative in spring and weakly negative in summer. Chl-a is higher in summer than in spring, while nutrient concentration is high in spring and low in summer there. A positive relationship between pCO2w and Chl-a is found in the Barents Sea in summer when Chl-a values decline while pCO2w remains at a relatively constant low level. In the Kara and East Siberian Seas and the Bering Strait, the relationships are positive because of high pCO2w and Chl-a water in the coastal region.
We estimated monthly air–sea CO2 flux in the Arctic north of 60°N from 1997 to 2014 by applying a self-organizing map technique with Chl-a, SST, SSS, SIC, xCO2a, and geographical positions. The addition of Chl-a as a training parameter enables us to improve the estimate of pCO2w through reproducing its decline in spring by biological production. A significant CO2 uptake of 180 ± 130 TgC yr–1 in the Arctic Ocean was obtained. This estimate has been much improved compared to a previous estimate thanks to the use of Chl-a, but to some extent also due to a higher number of CO2 data.