National POES System (NPOESS) is scheduled to fly during the 2007-2010 period. The impact of future instruments such as Doppler Wind Lidar (DWL) need to be assessed with experiments using simulated observations. These experiments are known as Observing System Simulation Experiments (OSSEs). OSSE will provide a guideline for selection and design of the instrument.

The first "nature run" (true atmosphere for the OSSEs) was provided by the European Centre for Medium- Range Weather Forecasts (ECMWF) for February 1993. Alternative nature run has been also prepared by NASA/DAO including summer and being evaluated.

Data impact of existing instruments in real and simulated data are compared for calibration. The impact test showed satisfactory similarity on TOVS 1B data and RAOB wind between real and simulated analysis. For DWL OSSE, the bracketing OSSEs have been performed for various concepts to bound the technology neutral potential impact. The results show that scanning is most important particularly in upper atmosphere.. OSSEs for atmospheric infrared sounder (AIRS) and cloud motion vectors (CMV) are under preparation. In this presentation

OSSE for other instruments such as cross track infrared sounder (CrIS), conically scanning microwave imager/sounder (CMIS), advanced technology microwave sounder (ATMS) are also being considered.

In this presentation detail and various aspects of calibration process and simulation procedure which will affect the interpretation of OSSE will be discussed. Plan and strategies for AIRS and CMV OSSE will be presented.