Short Range Cloud Reflectivity Measurement Using X-Band Primary Surveillance Radar

A systematic procedure for using X-Band Primary Surveillance Radar (PSR) for the application of short range weather observation, forecasting and nowcasting has been presented in the paper. PSR stationed at Thumba Equatorial Rocket Launching Station (TERLS) operates in X-Band (9.3-9.5 GHz) having the capability to detect sea and airborne targets of Radar cross section of 10sq.m upto a range of 100km. The small wavelength of operation has enabled PSR to detect tiny rain droplets and lighter precipitation at the compromise of higher rain attenuation. The reflectivity from the hydrometers is calculated from the back scattered power in PSR after compensating for ground clutter and attenuation due to precipitation. The reflectivity values are then compared with the C-Band Polarimetric Doppler Weather Radar (DWR) stationed near to PSR. Good correlation has been observed in the data products upto the slant range of 50km. Using the Z-R (reflectivity - rainfall rate) relation, the rainfall estimate has been computed. The procedure formulated and validated in this paper reveals the utility of PSR as a short range weather Radar and also as a calibration tool for DWR.