An internationally collaborative effort for Observing System Simulation Experiments, called Joint OSSE, was formed during past several years. OSSEs which allow the quantitative assessment of the analysis and forecast impact is called Full OSSEs. In a Full OSSE, all major observations used for the DAS have to be simulated as a control observation in addition to the observations to be tested by OSSEs. Simulation of control observations and OSSE calibration are the most significant initial investments for a full OSSE before it can be used to evaluate data impact of future instruments. This fundamental work requires diverse expertise and sufficient resources among different NOAA agencies. NCEP and NESDIS have volunteered to simulate control observations. Calibrations of OSSE systems using the NCEP global data assimilation system are being conducted at ESRL and NCEP.

Simulated data and a data base for alternative simulations for 2005-2006 observing system have been prepared and made available through the NASA/GSFC/NCCS portal, where the Nature Run is also available. The simulation software is also provided through the Joint OSSE web site. The calibration and simulation effort at NOAA is coordinated with work being done at NASA/GSFC/GMAO.

Providing Nature Run, truth for OSSE, must be produced by the state of the art forecast model. The first Joint OSSE Nature Run was produced by the European Center for Medium-Range Weather Forecasts (ECMWF). This Nature Run covers a 13 month period at T511 horizontal resolution with 91 vertical levels in 2006. A new Nature Run with higher resolution with improved model is being considered.

Space based Doper Wind Lidar (DWL) will provide three dimensional global wind profile is expected to improve NumericalWeather forecast significantly. Due to the cost of DWL, it has been the most important focus of OSSE for last two decades. JCSDA is conducting OSSE to evaluate DWL planned by NASA and ESA. Through OSSE NCEP data assimilation system is been prepared for DWL data. JCSDA is also working on OSSE to evaluate JPSS and DWSS data. For this experiments latest observing system for 2011-2012 are being simulated.