The Data Assimilation and Ocean Forecasting Unit is devoted to the development and implementation of data assimilation methods (OceanVar) and procedures. Data assimilation is the process that combines ocean observations with numerical models in order to provide the best estimate of the ocean state. This has a twofold application: production of global ocean reanalyses (C-GLORS) and high-resolution global ocean operational forecasts. The former activity is performed in the context of several international projects and initiatives, with the aim of providing an estimate of the ocean climate in the last decades, for use in climate studies, initialization of seasonal and decadal predictions, to serve as boundary or input for regional or downstream applications, respectively. The latter has the objective of producing forecasts of the ocean weather in real-time, for use in a variety of societal activities (e.g. search and rescue, oil spill, tourism, ship routing, etc.). The unit works in close cooperation with the Ocean and Sea-ice Modeling Unit, in particular collaborating on the configuration of the ocean general circulation model NEMO and sea-ice model LIM.