The Estuary Box Model, CMCC EBM, has been jointly developed by OPA Division of CMCC Foundation and the University of Bologna, Department of Physics and Astronomy. It is a time dependent numerical model based on two-layer averaged continuity and salinity conservation equations, linking the riverine freshwater and the salt sea waters (Verri et al., 2020; Verri et al., 2021).
The model has been conceived in order to represent the estuarine overturning circulation and mixing processes and to provide reliable estimates of runoff and salinity at river mouths, which in turn may be used to properly force ocean general circulation models that cannot represent the estuarine areas.
Its development started from scratch at CMCC in 2015 on the basis of the knowledge of another EBM (Sun et al., 2017) jointly developed by the University of Connecticut (UCONN) and the National Center for Atmospheric Research (NCAR).
Existing estuary box models include empirical and highly parameterized formula. The CMCC EBM is suitable to be coupled with regional-to-global ocean circulation and hydrology models: it requires a calibration of the estuary geometry (river mouth depth, width and length) and its output can be used for both operational forecasts and climate scenarios.
In a recent upgrade, a non-dimensional equation providing the time-variable estuary length has been included and this allows to estimate the length of the salt wedge intrusion.
A detailed description of the code and the model findings can be found at the model webpage https://www.estuaryboxmodel.org, where also news, publications, and other information can be gathered.
Figure. Sketch of the CMCC EBM. The volume fluxes entering or exiting the box along with their salinities are represented by arrows. Black arrows stand for input values from the ocean and river models and/or gauge stations, red arrows refer †o the unknowns solved by the EBM. The pairs of blue arrows represent the tidal mixing parametrized in the EBM equations.