Frequency Diversity Waveforms with ARM Cloud Radars

The ARM climate research facility has deployed scanning cloud radars in a variety of regimes around the world to study cloud properties. Cloud properties are essential for the treatment and representation of clouds in models. Cloud radars operate at millimeter wavelengths to observe smaller cloud particles when compared to the traditional weather radars operating at centimeter wavelengths. Range-velocity ambiguity often encountered in pulsed Doppler radars becomes more challenging for millimeter wavelength radars. The range-velocity ambiguity is a function of the pulse repetition frequency and wavelength of the radar. Radars at Ka-band and W-band operate at higher pulse repetition frequencies to make observation with smaller coverage in range and have acceptable Nyquist velocities. Traditional methods of using phase coded and staggered waveforms used will need to be augmented to resolve range and velocity ambiguities. ARM’s scanning cloud radars use a new frequency diversity and polarization agile staggered waveforms with phase coding to resolve range and velocity ambiguity. This paper presents an evaluation of the waveforms for polarimetric observations as well as Doppler moments at millimeter wavelengths. The evaluations are performed from data collected from SACR (Scanning ARM Cloud Radars) as well as simulations.