The Observing System Simulation Experiments for NPOESS

by

Michiko Masutani and Stephen J. Lord

EMC/NCEP/NWS/NOAA

Global atmospheric observing systems, such as those on Polar-orbiting Operational Environmental Satellites (POES), provide the basic data for Numerical Weather Prediction (NWP) forecasts and the means to monitor and assess climate. The National POES System (NPOESS) is scheduled to fly in the 2007-2010 time frame. For the next 10 years, a considerable amount of effort must take place to define, develop and build the suite of instruments which will comprise the NPOESS. The forecast impact of current instruments can be assessed by Observing System Experiments, in which already existing observations are denied or added to observations from a standard data base. The impact of future instruments, however, must be assessed with experiments using simulated observations. These experiments are known as Observing System Simulation Experiments (OSSEs).

A forecast model run, of one month duration, made by the European Centre for Medium-Range Forecasts at resolution T213 and 31 levels for starting from 5 February 1993 is chosen as the first "nature run" to simulate the atmosphere. A spaceborne Doppler wind lidar data is simulated from this nature run for the OSSEs.

Prior to the OSSEs, impact of actual TOVS radiance and radiosonde wind measurements are studied using the nNCEP operational data assimilation system. The results show significant impact of TOVS radiance data over the southern hemisphere and of radiosonde winds over the northern hemisphere.