A Radar Radial Velocity Assimilation Operator Based on IVAP Method

Radar data are helpful for improving high resolution numerical weather prediction. Because radar radial velocity is the projection of two components of wind on one direction, an observation operator is required to assimilate it. In this study, an improved Doppler radar radial velocity assimilation observation operator is proposed based on the integrating velocity–azimuth process (IVAP) method. This improved operator can ingest both radial wind and its spatial distribution characteristics to deduce the two components of the mean wind within a given area. Because the improved observation operator is defined within a given area, which can be uniformly chosen in both the observation and analysis coordinate systems, it has a thinning function. The traditional observation operator and the improved observation operator, along with their corresponding data processing modules, were implemented in the community Gridpoint Statistical Interpolation analysis system (GSI). The single analysis unit experiments, a typhoon case experiment were carried out in this study to demonstrate the advantage of the new operator.