An Experiment in Global Divergent Initialization

Abstract

The consequences of using a divergent initialization procedure in a cyclic environment are investigated. The global analysis-forecast system currently operational at the National Meteorological Center (NMC) is used in the investigation. The global analyses in this system are essentially nondivergent. The 6 h forecast divergence produced by the global model is in good synoptic agreement with the analyzed mass field valid at the time of the forecast. Nevertheless, the divergent initialization causes only small changes in both the global analyses and forecasts. The small changes in the forecast have no significant impact on the verification scores and do not tend to accumulate over several analysis-forecast cycles. It is concluded that divergent initialization neither degrades nor improves the performance of the global analysis-forecast System currently operational at NMC.