Development towards an initial version of the Global Constituent Data Assimilation System (GCDAS)

This Office Note documents the configuration and performance of the aerosol data assimilation component of the Global Chemistry and Aerosols Forecast System (GCAFS), the Global Constituent Data Assimilation System (GCDAS). The primary emphasis is on the specification and implementation of background error statistics, covariance modeling, and observation assimilation within the Joint Effort for Data assimilation Integration (JEDI) framework. A brief description of the forecast model configuration is provided for context; however, the focus of this document is on the aerosol data assimilation methodology rather than on the meteorological data assimilation system or the model configuration and coupling.