ChuvaOnline: A X-Band Radar Network Used for High Spatial and Temporal Rainfall Monitoring

ChuvaOnline is a project that monitors rain at high temporal and spatial scale over the city of São Paulo, Brazil, by means of X band radar network. The network is based on 3 X band weather radars deployed in the city of São Paulo Brazil: 2 mini-radars manufactured Eldes and 1 polarimetic built by Novimet. The 3 weather radar were installed 20 km a part of each other and are under the coverage of a S-band Doppler dual polarimetic radar. The radars are configured to make a single PPI elevation every two minutes with a gate resolution of 90 (mini-radar) and 75 (XPOL) meters and 21.6 (mini-radars) and 60 (XPOL) km coverage. After attenuation correction, the 3 X-band weather radars are integrated to provide rainfall maps with 100 meter resolution every 2 minutes. Intercomparisons with the polarimetric S-Band (60 km a part from the X-band radas, manufactured by Selex) show similarities in the radar reflectivity fields, but under convective cores the X-band radars show fine spatial structures that are smooth out by the S-Band radar. Nonetheless, despite the short range coverage set for the X-band radars, attenuation is problematic and some cases of full extinction have been found during some hail thunderstorms. Preliminary results against rain guages that have 10 minutes accumulation interval show: a) radar rain estimates are in phase with the observations; b) at hourly accumulations, the rain radar estimates are higher than the observations. During the conference an overview of the X band radars will be presented, including the gain of the higher temporal and spatial sampling, integration and rain radar estimate procedures, attenuation problems and a comparison with the rainfall maps retrieved by the SPOL.