This computation involved: GEOS-1 multiyear assimilation deployed on NASA Global Modelling and Assimilation Office (GMAO). GEOS-1 is an assimilation system developped by NASA GMAO to produce the 4D Assimilation Monthly Mean Subset Data available on the CIDC cd-rom. The Global Modeling and Assimilation Office (GMAO) was formed from the Data Assimilation Office (DAO), which focused on atmospheric modeling and data assimilation, and the NASA Seasonal-to-Interannual Prediction Project (NSIPP), which focused on coupled (ocean-atmosphere-land-surface) climate modeling and prediction and on ocean and land data assimilation. In addition to developing, integrating and using these systems for research, GMAO routinely generates products for use by some of NASA's instrument teams and by the U.S. operational climate prediction centers (NOAA's National Centers for Environmental Prediction (NCEP) and the International Research Institute for Climate Prediction (IRI)). GMAO addresses the optimal use of satellite and in situ observations to generate research quality data sets for climate analyses and also for weather, climate, and air quality forecasts. Their modeling and assimilation research includes coupling to and assimilation of atmospheric chemistry and ocean biology and carbon.