A new data collection strategy for the second-generation Ka-band Atmospheric Radiation Measurement zenith pointing radars

The U.S. Department of Energy operates millimeter wave radars in several climatologically distinct regions through the Atmospheric Radiation Measurement (ARM) Climate Research Facilities. Both zenith pointing and scanning radars operate at the Ka-band frequency, and provide unique information about the extent and content of clouds. Historically, several waveforms were used on the zenith pointing Millimeter-Wavelength Cloud Radars (MMCRs), and currently on the Ka-band ARM Zenith Radars (KAZRs), to obtain meaningful measurements for a variety of atmospheric conditions. An evolution in this methodology has been implemented in the second generation KAZRs (KAZR2), and allows for improvement in cloud retrieval capabilities.

The KAZR2s are located in the ARM Mobile Facility 3 (AMF3) in Oliktok, Alaska as well as the Eastern North Atlantic (ENA) site. Good radar sensitivity is paramount to the detection high-altitude cirrus clouds and is achieved through the use of pulse compression. In some instances of heavy rain the radar receivers saturate and mask details of cloud structures. The KAZR2s use two successive operational modes to combat this issue. Both are of identical waveform design, but the second mode is attenuated on transmit. When combined, both high sensitivity and precipitation returns can be collected on a continual basis, reducing the loss of cloud sampling capabilities due to saturation. In this work, a hardware description of the KAZR2 systems will be presented along with a discussion of the data collection methodology. Demonstrative data collections will be showcased as well.