Analysis and Impact of Super-obbed Doppler Radial Velocity in the NCEP Grid-point Statistical Interpolation (GSI) Analysis System

Doppler radar has the capability to scan large volumes of the atmosphere at high spatial and temporal resolutions. The real time access to the data from the entire WSR-88D network now available provides an unprecedented opportunity for using the data in operational numerical weather prediction (NWP) models. However, because of the huge volumes of radar data, current operational data assimilation system cannot directly assimilate all of them. The relatively low resolutions of the current operational models also make the assimilation of full-volume data unnecessary.

The fact that the definition of the radial velocity changes with the position of data relative to the radar poses an additional challenge not present with other types of data; special treatment is therefore needed. In this paper, the NCEP “super-obbing” technique for radar radial velocity is used to thin the Level-II radar data and the “super-obbed” data are then analyzed in the NCEP unified GSI analysis system. The impact of the super-obbed data on the analysis will be examined. Forecast impact studies will also be performed in the future.