The Environmental Modeling Center (EMC) of the National Centers for Environmental Prediction (NCEP) has been developing a new unified global/regional analysis system. This system, the Gridpoint Statistical Interpolation (GSI) analysis system, is intended to be the basis of future variational analysis system developments for all regional and global atmospheric applications within NCEP. The system has been developed as an operational code, but is intended to be flexible and easily used by external collaborators. Currently there are 27 different external collaborators have used the system and some (such as NASA/GMAO and ESRL/GSD) have contributed enhancements back into the GSI analysis system. The GSI analysis system became the operational system in the regional data assimilation system for the WRF/NMM model on 20 June 2006 and will be implemented as part of the operational Real-Time Mesoscale Analysis on 15 August 2006. It is scheduled to become the operational global assimilation system in January 2007 and is planned to replace the Regional Update Cycle analysis system.

The presentation will give an overview of the GSI analysis system as well as discuss the current status, recent developments and future plans. Topics to be discussed will include the background errors definition using recursive filters in grid space, the use of observations from conventional and space based observing systems, the incorporation of balance constraints in the analysis system and current performance results within the operational NCEP environment.