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

2025-08-21T07:42:19Z

Title: Assessment of austral autumn air-sea CO2 exchange in the Pacific sector of the Southern Ocean and dominant controlling factors Authors: Mo, Ahra; Park, Keyhong; Park, Jisoo; Hahm, Doshik; Kim, Kitae; Ko, Young Ho; Iriarte, Jose Luis; Choi, Jung-Ok; Kim, Tae-Wook Abstract: The factors that control the partial pressure of carbon dioxide (pCO2) in the Pacific sector of the Southern Ocean were investigated in April 2018, onboard the icebreaker, ARAON. The mean (± 1σ) of the sea surface pCO2 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 pCO2 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 pCO2 exhibited a strong correlation with salinity and the difference between the O2/Ar (ΔO2/Ar) values of the sample and air-saturated water in the north and south of the SB, respectively. The pCO2 in the ABS and western WAP/WS displayed a strong correlation with salinity. Furthermore, ΔO2/Ar and sea ice formation appear to be the dominant factors that control pCO2 in the Confluence Zone (CZ) and northern parts of WAP/WS. The estimated air-sea CO2 fluxes (positive and negative values indicate the source and sink for atmospheric CO2, 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 CO2 flux were observed in the CZ. Our results are the most recent observation data acquired in austral autumn in the Southern Ocean.

Seasonal variation of inorganic carbon parameters and air-sea exchange of CO2 in Marian Cove, King George Island, Western Antarctic Peninsula

2025-08-21T05:09:07Z

Title: Seasonal variation of inorganic carbon parameters and air-sea exchange of CO2 in Marian Cove, King George Island, Western Antarctic Peninsula Authors: Mo, Ahra; Park, Keyhong; Yang, Eun Jin; Park, Jisoo; Kim, Tae-wook Abstract: Inorganic carbon parameters were observed in Marian Cove, King George Island, Western Antarctic Peninsula, to assess the impact of the Antarctic coastal regions on air-sea CO2 exchange. The variations in total alkalinity (TA) and dissolved inorganic carbon (DIC) were caused by ice melting, formation, and biological activities. The net annual air-sea CO2 flux (5.6 ± 11.8 mmol m- 2 d- 1) indicated that Marian Cove was a CO2 source in the atmosphere, suggesting the opposite role of the Antarctic coastal regions to the Southern Ocean in CO2 flux estimates. Finally, this study identified the controlling factors of the annual variation of TA and DIC for the first time through direct field observations in King George Island. This study indicated that Antarctic coastal regions can act as a CO2 source to the atmosphere. Thus, further investigations and continuous monitoring are required in the coastal areas to improve our understanding of global carbon cycles.

Impact of Sea Ice Melting on Summer Air-Sea CO2 Exchange in the East Siberian Sea

2022-09-07T01:56:42Z

Title: Impact of Sea Ice Melting on Summer Air-Sea CO2 Exchange in the East Siberian Sea Authors: Mo, Ahra; Yang, Eun Jin; Kang, Sung-Ho; Kim, Dongseon; Lee, Kitack; Ko, Young Ho; Kim, Kitae; Kim, Tae-Wook Abstract: The role of sea ice melting on the air-sea CO2 flux was investigated at two ice camps in the East Siberian Sea of the Arctic Ocean. On average, sea ice samples from the two ice camps had a total alkalinity (TA) of ∼108 and ∼31 μmol kg-1 and a corresponding salinity of 1.39 and 0.36, respectively. A portion (18-23% as an average) of these sea ice TA values was estimated to exist in the sea ice with zero salinity, which indicates the excess TA was likely attributed to chemical (CaCO3 formation and dissolution) and biological processes in the sea ice. The dilution by sea ice melting could increase the oceanic CO2 uptake to 11-12 mmol m-2 d-1 over the next 21 days if the mixed layer depth and sea ice thickness were assumed to be 18.5 and 1.5 m, respectively. This role can be further enhanced by adding TA (including excess TA) from sea ice melting, but a simultaneous release of dissolved inorganic carbon (DIC) counteracts the effect of TA supply. In our study region, the additional impact of sea ice melting with close to unity TA:DIC ratio on air-sea CO2 exchange was not significant.

Factors affecting the subsurface aragonite undersaturation layer in the Pacific Arctic region

2022-11-14T16:36:53Z

Title: Factors affecting the subsurface aragonite undersaturation layer in the Pacific Arctic region Authors: 모아라; 김동선; Yang, Eun Jin; Jung, Jinyoung; 고영호; Kang, Sung-Ho; Cho, Kyoung-Ho; Park, Keyhong; 김태욱 Abstract: This study evaluated interannual variation in the subsurface aragonite undersaturation zone (ΩAr<1 layer) in the Pacific Arctic Ocean, using data from the 2016？2019 period. The upper boundary (DEP^UB_ΩAr<1) of the Ω layer ΩAr<1 generally formed at a depth where the contribution of corrosive Pacific water was approximately 98 %. The intensity of the Beaufort Gyre associated with freshwater accumulation mainly determined interannual variation DEP^UB_ΩAr<1, but the direction of its effect was opposite west and east of ~166 W. The lower boundary (DEP^LB_ΩAr<1) of the ΩAr<1 layer was generally found at a depth range where equal contributions of Pacific and Atlantic water were expected. An Atlantic-origin cold saline water intrusion event in 2017 caused by an anomalous atmospheric LB circulation pattern significantly lifted the DEP^LB_Ω<1, thus the thickness of the ΩAr<1 layer decreased.