Algorithms to estimate the carbon dioxide uptake in the northern North Atlantic using shipboard observations, satellite and ocean analysis data

Observations of the surface-water fugacity of carbon dioxide (fCO(2)(SW)) measured during 2005 in the subpolar North Atlantic Ocean (58-62 degrees N, 10-40 degrees W) were used together with in situ ocean data and remotely sensed data to develop algorithms to estimate (fCO(2)(SW)). Based on multiple regression we found that sea-surface temperature (SST), mixed-layer depth (MLD), and chlorophyll a (chl a) contributed significantly to the fit. Two algorithms were developed for periods depending on the presence of chl a data. The correlation coefficient (r(2)) and the root-mean-square deviation (rms) for the best fit in the period when chl a was observed (20 March-15 October) were 0.720 and +/- 10.8 mu atm, respectively. The best fit for the algorithm for the period when no chl a was present (16 October-19 March) resulted in a r(2) of 0.774 and a rms of +/-5.6 mu atm. Based on these algorithms we estimated seasonal fields of (fCO(2)(SW)) and the air-sea CO(2) flux. The estimated net annual CO(2) sink was 0.0058 Gt C yr(-1) or 0.6 Mol C m(-2) yr(-1). (C) 2009 Elsevier Ltd. All rights reserved