Japan Geoscience Union Meeting 2023

Presentation information

[J] Online Poster

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG46] Science in the Arctic Region

Thu. May 25, 2023 10:45 AM - 12:15 PM Online Poster Zoom Room (9) (Online Poster)

convener:Tomoki Morozumi(National Institute for Environmental Studies), Rigen Shimada(Japan Aerospace Exploration Agency), Masatake Hori(University of Tokyo, Atmosphere Ocean Research Institute), Tatsuya Kawakami(Hokkaido University)

On-site poster schedule(2023/5/24 17:15-18:45)

10:45 AM - 12:15 PM

[ACG46-P03] Regional Carbon Cycle Assessment and Processes phase 2 (RECCAP2): CO2 uptake in the Arctic Ocean from 1985 to 2018

*Sayaka Yasunaka1,2, Manfredi Manizza3, Jens Terhaar4,5, Are Olsen6, Ryohei Yamaguchi2, Peter Landschützer7,8, EIJI WATANABE2, Dustin Carroll9, Hanani Adiwira1, Jens Daniel Müller10, Judith Hauck11 (1.Tohoku University, 2.JAMSTEC, 3.Scripps Institution of Oceanography, 4.Woods Hole Oceanographic Institution, 5.University of Bern, 6.University of Bergen and Bjerknes Centre for Climate Research, 7.Flanders Marine Institute, 8.Max Planck Institute for Meteorology, 9.San José State University, 10.ETH Zurich, 11.Alfred Wegener Institute for Polar and Marine Research)

Keywords:Sea-air CO2 flux, pCO2, Sea ice

As a contribution to the Regional Carbon Cycle Assessment and Processes phase 2 (RECCAP2) project, we present synthesized estimates of the Arctic Ocean CO2 uptake and their uncertainties from state-of-the-art 8 surface ocean pCO2-observation products, 18 global and regional ocean biogeochemical models and 6 atmospheric inversions. For the period of 1985−2018, the Arctic Ocean represents a net sink of CO2 of 103 ± 19 TgC yr−1 in the pCO2 products and 92 ± 30 TgC yr−1 in the ocean biogeochemical models. The CO2 uptake peaks in late summer and early autumn, and is low in winter because the sea ice cover inhibits sea-air fluxes. While the CO2 uptake in the Arctic Ocean is primarily caused by steady-state fluxes of natural carbon, it is enhanced by the atmospheric CO2 increase (28 ± 7 %) and climate change (16 ± 26 %). The annual mean of CO2 uptake increased with the decreasing sea ice concentration both in the pCO2 products and the ocean biogeochemical models (29 ±11 TgC yr−1dec-1 and 10 ± 4 TgC yr−1dec-1, respectively), and the climate effect in the Arctic Ocean has become more important in recent years. Both, the mean CO2 uptake and the trend, is substantially weaker in the atmospheric inversions. Uncertainty across all estimates is large especially in the estimated surface ocean pCO2 values in the East Siberian Sea and the Laptev Sea, due to scarcity of observations and missing processes in models, such as land-sea fluxes and sediment dynamics.