Simplified and regular physical parameterizations for incremental four-dimensional variational assimilation

A set of physical parameterizations has been developed for inclusion in inc remental four-dimensional variational assimilation (4D-Var). The goal for t his physical package is that it be simple, regular (for the efficiency of t he minimization in 4D-Var), and at the same time realistic enough. The pack age contains a simplified computation of radiative fluxes, vertical turbule nt diffusion, orographic gravity waves, deep convection, and stratiform pre cipitation fluxes. Its tangent-linear and adjoint counterparts have also be en developed. The validations of the simplified physical parameterizations and of the tangent-linear model with those included have been done. The imp ortance of regularization (removing some thresholds in physical parameteriz ations that can affect the range of validity of the tangent-linear approxim ation), which arises during validation of the tangent-linear model, is asse ssed.