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