The river–estuary–coastal ocean continuum serves as a critical ecotone linking terrestrial and marine carbon pools. The transport, transformation, and burial of carbon within this continuum are highly complex, making the land‑derived carbon flux into the ocean one of the most uncertain components in global carbon cycle research. Satellite remote sensing offers the capability to acquire sea surface information over large areas, at high frequency, and in near‑real‑time, while numerical models can depict three‑dimensional water structures, dynamic evolution of flow fields, and continuous changes in multi‑component biogeochemical processes. The deep integration of these two approaches has become a key technological pathway to address the challenges in estimating carbon fluxes across this complex continuum.
This report first systematically introduces a methodological framework for estimating carbon fluxes across the continuum based on the integration of satellite remote sensing and numerical modeling. In practical applications, focusing on typical large estuaries such as the Changjiang River Estuary and the Pearl River Estuary, we integrated multisource remote‑sensing ocean‑color data with three‑dimensional ocean dynamic–biogeochemical models like FVCOM (Finite Volume Community Ocean Model) to estimate both the POC flux transport to the estuaries and the net carbon fluxes exported to the open ocean, and further analyzed their long‑term trends and driving mechanisms. In response to the scarcity of monitoring data for small‑ and medium‑sized rivers in Zhejiang Province, we coupled high‑spatiotemporal‑resolution water quality remote sensing data with the SWAT model to construct a dynamic estimation framework for land‑derived material fluxes from these rivers. Building upon these practical studies, this report further synthesizes the key scientific questions currently facing research on carbon fluxes across the river–estuary–coastal ocean continuum, and systematically elaborates an integrated technical methodology system encompassing “stereoscopic monitoring, numerical simulation, and comprehensive assessment” for this continuum. This system is intended to provide technical support for the establishment of a stereoscopic monitoring framework and the quantitative evaluation of integrated land‑sea carbon fluxes.