Basin-scale pCO2 maps estimated from ARGO float data: A model study

• Published in: Journal of Geophysical Research
• Main Authors: Friedrich, Tobias, Oschlies, Andreas
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 2009
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/947/; https://oceanrep.geomar.de/id/eprint/947/1/763_Friedrich_2009_BasinscalePco2MapsEstimatedFrom_Artzeit_pubid12299.pdf; https://doi.org/10.1029/2009JC005322

A novel method for mapping surface pCO(2) on a basin scale using ARGO floats is presented and tested in the framework of an eddy-resolving biogeochemical model of the North Atlantic. Voluntary observing ship (VOS) and ARGO float coverage of the year 2005 is applied to the model to generate synthetic "observations." The model-generated VOS line "observations'' of pCO(2), SST, and SSS form a training data set for a self-organizing neural network. The trained neural network is subsequently applied locally to estimate pCO(2) from the model-generated ARGO float SST and SSS data. The local pCO(2) estimates at the simulated float positions are extrapolated using objective mapping. The accuracy of the nearly basinwide pCO(2) estimates is assessed by comparing against the pCO(2) output of the model that serves as synthetic "ground truth.'' For an ARGO float coverage of the year 2005, the resulting monthly mean pCO(2) maps cover 70% of the considered area (15 degrees N to 65 degrees N) with an RMS error of 15.9 mu atm. Compared to remote sensing-based estimates that suffer from large regional gaps in optical satellite data coverage, the RMS error in reproducing the annual cycle of pCO(2) can be reduced by 42% when the more evenly distributed ARGO float-based data are used.