The quality index for radar precipitation data: a tower of Babel?

One of the quantitative metrics of quality of radar measurements of precipitation is the quality index (QI): a field of numbers whose values depend on the quality. Such an approach is operationally used in some national meteorological services. Difficulties in using this approach can be observed due to hardware and software differences and continuous quality control algorithm improvement. An overall review of commonly used approaches and connected difficulties is made. The challenges in hydrological applications using the QI are listed, as the technique is used to generate precipitation field ensembles. Recommendations for future common considerations are suggested. Copyright (C) 2010 Royal Meteorological Society