EnKF data assimilation and dual-Doppler analysis of the 29 May 2004 Geary, Oklahoma supercell

On 29 May 2004, a long-track supercell storm moved across Oklahoma producing multiple tornadoes and numerous reports of large hail. Two mobile, C-band, Doppler (SMART-R) radars collected data in 2.5 min volume scans almost continuously for more than three hours. Dual-Doppler analyses were completed for select times using a1 km grid spacing and a 2-pass Barnes objective analysis in the interpolation of radial velocities and reflectivity to a Cartesian grid following Majcen et al (2008).

The focus of the radar data assimilation for this study is to retrieve the state of the storm rather than to develop forecast applications. For this purpose, the ensemble Kalman filter (EnKF) technique is used to assimilate reflectivity and/or radial velocity data into the model from SMART radar at approximately five minute intervals. Comparisons of the simulations employing EnKF to a simulation without data assimilation and to the dual-Doppler syntheses at various times of the storm's life-cycle will be presented. These results will be used to quantify the agreement between the simulation and the observations providing background such that future studies may use the simulations in order to to retrieve unobserved fields.