Variations in the summer oceanic p CO 2 and carbon sink in Prydz Bay using the self-organizing map analysis approach

• Published in: Biogeosciences
• Main Authors: S. Xu, K. Park, Y. Wang, L. Chen, D. Qi, B. Li
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2019
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Prydz Bay; Southern Ocean; Sea ice
• Online Access: https://doi.org/10.5194/bg-16-797-2019; https://doaj.org/article/46a47d85784f4d128536f7c17ea180e8

This study applies a neural network technique to produce maps of oceanic surface p CO 2 in Prydz Bay in the Southern Ocean on a weekly 0.1 ∘ longitude × 0.1 ∘ latitude grid based on in situ measurements obtained during the 31st CHINARE cruise from February to early March 2015. This study area was divided into three regions, namely, the “open-ocean” region, “sea-ice” region and “shelf” region. The distribution of oceanic p CO 2 was mainly affected by physical processes in the open-ocean region, where mixing and upwelling were the main controls. In the sea-ice region, oceanic p CO 2 changed sharply due to the strong change in seasonal ice. In the shelf region, biological factors were the main control. The weekly oceanic p CO 2 was estimated using a self-organizing map (SOM) with four proxy parameters (sea surface temperature, chlorophyll a concentration, mixed Layer Depth and sea surface salinity) to overcome the complex relationship between the biogeochemical and physical conditions in the Prydz Bay region. The reconstructed oceanic p CO 2 data coincide well with the in situ p CO 2 data from SOCAT, with a root mean square error of 22.14 µ atm. Prydz Bay was mainly a strong CO 2 sink in February 2015, with a monthly averaged uptake of 23.57±6.36 TgC. The oceanic CO 2 sink is pronounced in the shelf region due to its low oceanic p CO 2 values and peak biological production.