Variations inthe Summer Oceanic p CO 2 and Carbon Sink in the Prydz 1 Bay Using the SOM Analysis Approach

12 This study applies a neural network technique to produce maps of oceanic surface pCO2 in the 13 Prydz Bay in the Southern Ocean on a weekly 0.1° longitude  0.1° latitude grid based on in situ 14 measurements obtained during the 31st CHINARE cruise from February to early March of 2015. 15 This study area was divided into three regions, namely, the Open-ocean region, Sea-ice region and 16 Shelf region. The distribution of oceanic pCO2 was mainly affected by physical processes in the 17 Open-ocean region, where mixing and upwelling were the main controls. In the Sea-ice region, 18 oceanic pCO2 changed sharply due to the strong change in seasonal ice. In the Shelf region, 19 biological factors were the main control. The weekly oceanic pCO2 was estimated using a 20 self-organizing map (SOM) with four proxy parameters (Sea Surface Temperature, Chlorophyll-a 21 concentration, Mixed Layer Depth, and Sea Surface Salinity) to overcome the complex 22 relationship between the biogeochemical and physical conditions in the Prydz Bay region. The 23 reconstructed oceanic pCO2 data coincide well with the in situ investigated pCO2 data from 24 SOCAT, with a root-mean-square error of 22.14 μatm. The Prydz Bay was mainly a strong CO2 25 sink in February 2015, with a monthly averaged uptake of 23.576.36 TgC. The oceanic CO2 sink 26 is pronounced in the Shelf region due to its lowest oceanic pCO2 and peak biological production. 27