Opportunities and Challenges of Variable Change Architecture in JEDI

The JEDI framework is integrated with multiple earth-system models, including FV3, MPAS, LFRic, and MOM6 for data assimilation. Since changes of variables are required in multiple parts of the DA process, for example in observation operators and background error covariances, JEDI has generic interfaces for handling these variable changes. In recent years, these interfaces have evolved in significant ways, and a new JEDI repository for handling variable changes in a model-agnostic way (VAariable DErivation Repository, or VADER) has been introduced. These changes have implications for how JEDI model interfaces can further adapt their variable change modules to fully leverage the JEDI generic capabilities, and how JEDI can expand to meet their needs. In this presentation we will discuss the current state of VADER and variable changes in JEDI, as well as future plans.