Assessment of austral autumn air–sea CO2 exchange in the Pacific sector of the Southern Ocean and dominant controlling factors

• Published in: Frontiers in Marine Science
• Main Authors: Mo, Ahra, Park, Keyhong, Park, Jisoo, Hahm, Doshik, Kim, Kitae, Ko, Young Ho, Iriarte, José Luis, Choi, Jung-Ok, Kim, Tae-Wook
• Other Authors: Korea Polar Research Institute, National Research Foundation of Korea
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Frontiers Media SA 2023
• Subjects: Antarc*; Antarctic; Antarctic Peninsula; Bellingshausen Sea; Ross Sea; Sea ice; Southern Ocean; Weddell Sea
• Online Access: http://dx.doi.org/10.3389/fmars.2023.1192959; https://www.frontiersin.org/articles/10.3389/fmars.2023.1192959/full

The factors that control the partial pressure of carbon dioxide ( p CO 2 ) in the Pacific sector of the Southern Ocean were investigated in April 2018, onboard the icebreaker, ARAON. The mean (± 1σ) of the sea surface p CO 2 was estimated to be 431 ± 6 μatm in the north of the Ross Sea (NRS), 403 ± 18 μatm in the Amundsen–Bellingshausen Sea (ABS), and 426 ± 16 μatm in the western Antarctic Peninsula and Weddell Sea (WAP/WS). The controlling factors for p CO 2 in the NRS appeared to be meridionally different based on the southern boundary of the Antarctic Circumpolar Current (SB; ~62.5°S in the Ross Sea). The sea surface p CO 2 exhibited a strong correlation with salinity and the difference between the O 2 /Ar (ΔO 2 /Ar) values of the sample and air-saturated water in the north and south of the SB, respectively. The p CO 2 in the ABS and western WAP/WS displayed a strong correlation with salinity. Furthermore, ΔO 2 /Ar and sea ice formation appear to be the dominant factors that control p CO 2 in the Confluence Zone (CZ) and northern parts of WAP/WS. The estimated air–sea CO 2 fluxes (positive and negative values indicate the source and sink for atmospheric CO 2 , respectively) range from 3.1 to 18.8 mmol m −2 d −1 in the NRS, −12.7 to 17.3 mmol m −2 d −1 in the ABS, and −59.4 to 140.8 mmol m −2 d −1 in the WAP/WS. In addition, biology-driven large variations in the air–sea CO 2 flux were observed in the CZ. Our results are the most recent observation data acquired in austral autumn in the Southern Ocean.