Arctic Ocean CO2 uptake: an improved multiyear estimate of the air–sea CO2 flux incorporating chlorophyll a concentrations

[摘要] We estimated monthly air–sea CO₂ fluxes in the Arctic Ocean and its adjacent seas north of 60° N from 1997 to 2014. This was done by mapping partial pressure of CO₂ in the surface water (pCO_2w) using a self-organizing map (SOM) technique incorporating chlorophyll a concentration (Chl a), sea surface temperature, sea surface salinity, sea ice concentration, atmospheric CO₂ mixing ratio, and geographical position. We applied new algorithms for extracting Chl a from satellite remote sensing reflectance with close examination of uncertainty of the obtained Chl a values. The overall relationship between pCO_2w and Chl a was negative, whereas the relationship varied among seasons and regions. The addition of Chl a as a parameter in the SOM process enabled us to improve the estimate of pCO_2w, particularly via better representation of its decline in spring, which resulted from biologically mediated pCO_2w reduction. As a result of the inclusion of Chl a, the uncertainty in the CO₂ flux estimate was reduced, with a net annual Arctic Ocean CO₂ uptake of 180 ± 130 Tg C yr⁻¹. Seasonal to interannual variation in the CO₂ influx was also calculated.

[学科分类] 地球化学与岩石