The UMass Mobile W-Band Radar: System Overview and Sample Observations

The Microwave Remote Sensing Laboratory (MIRSL) at the University of Massachusetts has maintained and operated a mobile W-band Polarimetric Doppler Radar since the early 1990s. This radar has been a focal point of ongoing collaboration between UMass and the Univer-sity of Oklahoma School of Meteorology in studies of se-vere thunderstorms and tornadoes using mobile radars. Over the past two years, the W-band radar has under-gone a major rebuild and upgrade. Modifications include a new modulator for the klystron transmitter and associ-ated redesign to accommodate the same, a new control and data acquisition system based on FPGA and digital receiver technology, real-time display, and new mechan-ical packaging, and conversion of the entire system to battery power recharged by the truck’s engine, eliminat-ing the need for a generator. Due to the 3 mm wavelength of the radar, the unam-biguous velocity interval for W-band radars is very nar-row. A limitation of the prior data acquisition system was a single pulse-pair interval requiring use of polarization-diverse pulse-pair methods to obtain unwrapped veloc-ities in high-wind events. The new system relieves this constraint allowing dual- or multiple-PRT methods to ob-tain unwrapped velocities. Real-time full spectrum (FFT) processing is in development. This paper documents the upgraded system and shows selected results from recen