Observation System Simulation Experiment

Observing System Simulation Experiments (OSSEs) are a powerful tool to assess added value of planned or hypothetical observing systems for weather analysis and prediction. Although a large initial investment is required for OSSE, using an OSSE is the most reliable strategy today to assess the quantitative impact from prospective observing systems.

The 13 month long (From May 2005-May2006) Joint OSSE Nature Run was produced by the European Center for Medium-Range Weather Forecasts (ECMWF) and shared with the internationally collaborative Joint OSSE community. A simulation of observations over the Nature Run period for control experiments, based on the observations available during the period, was completed by the National Centers for Environmental Prediction (NCEP) and Joint Center for Satellite and Data Assimilation (JCSDA) and shared with the Joint OSSE community. Initial conditions for NCEP global model are also provided.

JCSDA has conducted OSSE to assess data impact of DWL and additional satellites in Early-Morning Orbits. Further OSSE to evaluate Geostationary Hyperspectral Data, additional GPSRO and Arctic Observation are planned. The same Nature Run was used by OSSE at Environment of Canada, NOAA/ESRL, NASA/GMAO, NOAA/AOML, University of Wisconsin and other institute. Using the same Nature Run made collaboration in OSSEs possible. More institutes are showing interests are taking advantage of available resource for OSSEs.

JCSDA is acquiring a new higher resolution Nature run to evaluate data impact in smaller scale such as hurricanes. Repeating OSSE with Nature Runs will allow to gain further confidence in OSSE experiments.