Computational aspects of chemical data assimilation into atmospheric models

The task of providing an optimal analysis of the state of the atmosphere requires the development of novel computational tools that facilitate an efficient integration of observational data into models. In this paper we discuss some of the computational tools developed for the assimilation of chemical data into atmospheric models. We perform a theoretical analysis of discrete and continuous adjoints for stiff differential equation solvers. Software tools particularly tailored for direct and adjoint sensitivity analysis of chemical systems are presented. The adjoint of the state-of-the-art model STEM-III is discussed, together with ozone assimilation results for a realistic test problem.