Error analysis of TMI rainfall estimates over ocean for variational data assimilation

An intercomparison of retrieval errors from different Tropical Rainfall Measuring Mission (TRMM) passive microwave products was carried out to assess the definition of observation error for experiments of rainfall assimilation in a variational framework. Depending on algorithms and their spatial resolution and sampling, a large variety of error estimates occurred. The error propagation to the European Centre for Medium-Range Weather Forecasts (ECMWF) model grid (here 45 and 60 km) was investigated from error simulations and observed data with and without accounting for spatial error correlation.