Storm-tracking and thunderstorm nowcasting for Sao Paulo State, Brazil

The State of Sao Paulo has 3 S-Band weather radars (2 Doppler) operated by the state government that supports the new hydro-meteorological system known as SIHESP. Under this program, these radars are being integrated to provide continuous storm monitoring over the state. This integration herein named 3D-PPT has a horizontal resolution of 2km x 2km and a vertical resolution of 0.5 km from 1.5 to 7 km height and 1.0 km from 7 to 20 km height, while the time interval is 15 minutes. In addition, lightning measurement from the Brazilian lightning detection network (RINDAT) are also integrated to identify which storms become thunderstorms. Based on this data set, a storm-tracking algorithm is applied to depict the life cycle of those storms, and therefore, understand the main characteristics for thunderstorm development. This study will present the main processes involved during the volumetric radars integrated and the life cycle of general storms and thunderstorms. From an initial period of 6 stormy days from January 15th to 21st, 2003, an amount of 210 volume scans were integrated. In order to check if this volumetric integration presented meaningful results, we have initially compared the reflectivity fields for the 3 km height CAPPI's in the intersection areas. These comparisons showed similar reflectivity factor distribution for the integrated volscans and individual radars. Additionally, a second test will be performed to depict the existence of any reflectivity bias by using the Precipitation Radar of TRMM satellite. In that comparison, we will apply the same methodology adopted by Anagnostou et al. (2002). As for the life cycle of storms, we are adjusting a rain storm-tracking algorithm to describe temporal evolution. The tracking algorithm computes the morphological parameters of the rainy cell. For instance we are applying a threshold of 20 dBZ. During the conference we will present the mean temporal evolution of the vertical profiles of Z in the convective and stratiform region for both storms with and without lightning. An analysis will be employed to seek any dependence of the maximum size of the storms or lifetime duration.