Particulate organic carbon export flux is a key indicator of the ocean biological carbon pump. Food-web models have been demonstrated to be a reliable approach for estimating marine POC export by describing the transformation of primary production through grazing, respiration, mortality, aggregation, and sinking. However, most existing satellite-based food-web models are based on mass balance within the mixed layer, and therefore their outputs mainly represent POC export at the mixed-layer depth. Here, we propose a stock-based satellite approach to estimate POC export flux at specific depths. By incorporating satellite-derived or satellite-constrained POC stock into the food-web framework, the mass balance can be extended from the mixed layer to a defined water column. This allows the export flux to be estimated at target depths, including the euphotic depth, rather than being limited to the mixed-layer base. This framework links satellite observations, POC inventory, and food-web processes in a depth-explicit manner, providing a practical pathway for developing large-scale satellite products of vertical POC export flux and improving assessments of the ocean biological carbon pump.