Q2 radar QPE quality index: an attempt to quantify radar QPE uncertainties in a national radar network

The next-generation multi-sensor quantitative precipitation estimation (QPE), or “Q2”, is an experimental hydrometeorological system that integrates data from radar, rain gauge, and atmospheric models and generates high-resolution precipitation products on the national scale in real-time. The quality of the Q2 precipitation products varies in space and in time due to a number of factors. In the current study, a Radar QPE Quality Index (RQI) field is developed to quantify the Q2 radar-based QPE uncertainties. The RQI field accounts for radar beam sampling characteristics (blockage, beam height and width) and their relationships with the atmospheric freezing level. A national RQI map is generated by mosaicing single radar RQI fields based on radar densities in the network. Initial results show that the RQI field correlates well with spatial distributions of radar QPE errors with respect to gauges. The radar quality information is useful to the radar product users and can add value in radar product applications.