The ARM's redesigned X band Scanning Precipitation Radar Network in the Southern Great Plains, Oklahoma

The Atmospheric Radiation Measurement (ARM) facility’s X-band dual-polarization Scanning Precipitation Radars (X-SAPR) were designed and deployed in Northern Oklahoma at the Southern Great Plains (SGP) site in 2011 as a part ARM. The network topology is such that the three X-SAPRs form a triangle with approximate distance of 25 km between the radars. The three radars can be configured in three pairs for dual-Doppler measurements, with data collection above SGP central facility where additional profiling and ins-situ instruments are deployed. Reliable radar operations were limited due analog antenna position controller and an upgrade was much needed. The antenna controller was upgraded to a more accurate and responsive digitally controlled system. A new all-digital control system was implemented with intelligent digitally controlled servo amplifiers, and high-precision on-axis optical encoders. Vaisala Radar Control Processor (RCP8) has been integrated with the new digital motion controller because the system was designed with the Vaisala RVP900 digital Receiver, signal processor, and IRIS radar software). This paper provides a brief description of the installed hardware, calibration, and characterization of the radars, along with results to evaluate their performance.