Integrated Perspective of the Biological Pump in the North Pacific: Synergy from BGC-Float Observations and Ecosystem Model Simulation

Abstract

The North Pacific (>20°N) stands out as a significant carbon sink, contributing to approximately 25% of the global oceanic CO2 uptake and absorbing around 0.5 Pg C yr-1 from the atmosphere. Despite the well-established importance of the biological carbon pump in maintaining this regional carbon sink, our current understanding of the strength and efficiency of the biological pump in this vast region remains incomplete. Historical studies have primarily relied on extrapolations from a limited number of observations. In this study, we utilize data from 85 BGC-floats, covering over 160 annual cycles, to constrain essential fluxes relevant to the biological pump in the North Pacific, including net primary production, the export of distinct biogenic carbon, and air-sea CO2 flux. Furthermore, we combine the output from a well-constrained regional ecosystem model (ROMS-CoSiNE-Iron Model) to gain mechanistic insights into how the food-web dynamics drive the strength and efficiency of the biological carbon pump across different ecosystems. Overall, our study offers an integrated perspective on the North Pacific biological pump by leveraging high-resolution observations from the BGC-float array and simulation from an improved ecosystem model.