Dataset to the article 'The beach bioreactor: unraveling the anomaly of intensive carbon remineralization above a deep oxycline'

This repository contains model output files for the research article: Felix Auer, Janek Greskowiak, Rena Meyer, Anja Reckhardt, Moritz Holappels (2025), The beach bioreactor: unraveling the anomaly of intensive carbon remineralization above a deep oxycline Model description: A two-dimensional numerical reactive transport model was created, simulating tidal and wave-driven groundwater flow and oxygen (O2) dynamics in the saltwater recirculation cell of the beach aquifer at Spiekeroog Beach, Germany. The model was developed using COMSOL Multiphysics™ v.6.1 and couples variably saturated flow (Richards Equation) with reactive O2 transport. Boundary conditions and parameters were informed by field data, as described in the corresponding manuscript. Two seasonal scenarios (summer and winter) were simulated to capture differences in biogeochemical activity and inputs, and beach morphology. Atmospheric O2 input in the periodic tide-induced desaturated surface beach layer (re-aeration) and its effect on O2 distribution was explored via separate model runs. The simulations were performed in two stages: first resolving transient groundwater flow during a tidal cycle, then coupling with reactive transport to reach quasi-steady-state O2 profiles. Model Output: Model output files in this repisitory are available both for the "Summer" and the "Winter" simulation. Files with the ending "_flow_tidal_cycle" contain the 2D-values for hydraulic heads (m), as well as x- and y-component of the porewater flow velocity (m/s), resolved every 2 minutes for an entire tidal cycle (720 min). Files with the ending "_cO2_tidal_cycle" contain the 2D-values for oxygen concentration (µmol/l), resolved every 20 minutes for a quasi steady-state tidal cycle (720 min). Files with the ending "_cO2_tidal_cycle_NoReAir" contain the same, but with the re-aeration process switched off.