Estimating the biological carbon pump from satellite-based observations using a semi-analytical algorithm in the Arctic Ocean

The Arctic Ocean constitutes a globally significant carbon sink, where carbon sequestration is predominantly mediated by the biological carbon pump (BCP). Quantifying BCP magnitude and efficiency persists as a key challenge in marine carbon cycle research. Net community production (NCP) serves as a critical proxy for quantifying carbon export fluxes and assessing carbon sequestration efficacy. This study introduces the Nitrate-based Semi-Analytical Model (NSAM), an innovative framework advancing Arctic NCP quantification through synergistic integration of satellite-based observations, biogeochemical model and hydrodynamic processes. By integrating seasonal nitrate budgets derived from satellite-based observations and reanalysis data using a machine learning algorithm, the NCP is computed by applying Redfield stoichiometry (C: N = 6.6) to convert seasonal nitrogen changes into carbon export estimates. Results demonstrate strong agreement between satellite-derived NCP and in situ measurements (RMSD = 9.52 mmol C m⁻² d⁻¹), underscoring the utility of NSAM for quantifying the Arctic BCP. Satellite-based NCP provides unprecedented pan-Arctic spatial coverage, overcoming the limitations of ship-based methods constrained to discrete cruise tracks. This advancement enables refined assessments of the Arctic Ocean's contribution to global carbon sequestration dynamics.