Thermodynamical Retrieval in Severe Local Storm from Dual Rapid-Volume-Scan Observations during Summer Seasons in Tokyo Metropolitan Region, Japan

The authors applied traditional thermodynamic retrieval methods (Gal-Chen, 1978) with considering wind acceleration term for several severe convective storms observed by two X-band polarimetric radars which performed sector scans at an azimuthal width of 60 degree with 1-2 minutes temporal resolution during summer seasons from 2011 to 2013 in Tokyo metropolitan region, Japan. Dual-Doppler radar analysis using variational method (Protat et al., 1999) was conducted before thermodynamical retriveal. Wind acceleration in advection term was explicitly estimated from rapid radar observation in thermodynamical retrieval. In this study, we investigated the impact of rapid volume scan to the thermodinamical retrieval and short-term forecasitng using thermodynamical retrived parameter. The retrieved potential temperature perturbation below 3 km ASL were assimilated by 3DVAR with incremental analysis update filter during the first 30 minutes of forecast. We investigated the impact to precipitation forecast up to 3 hours. Positive impact on precipitation forecast up to 1 hour ~ 1 hour half are found in almost all cases comparing with no-assimilation experiments. Sensitive experiments with lower temporal observation resolution (6 minutes) showed degradation of forecast.  We will propose realtime application of thermodynamical retrieval of local severe storms for improving short-range forecast  in Tokyo metropolitan region.