Assimilation Experiment On A Local Heavy Rainfall Event Using Doppler Lidar Observations

A cloud resolving 4D-Var system was applied to a local heavy rainfall event occurred on 5 July 2010 in the west of Tokyo. In the control assimilation experiment (CTL), radial wind field by meteorological Doppler Radars and GPS precipitable water vapor data were assimilated, while in the test experiment (LDR), radial winds by Lidar were assimilated furthermore. Comparative experiments show that the LDR forecast reproduces better the observed distribution and intensity of rainfall than the CTL forecast. Difference of zonal wind fields between CTL and LDR suggests that the low level wind modified by the Lidar data assimilation is important to obtain this result.