First Characterized, Corrected Data Available From Fixed-Site KAZRs

Published: 20 November 2025

A group of eight plots with the overarching title "NSA KAZR Mask 20231022." The plots are titled GE Reflectivity, MD Reflectivity, GE SNR, MD SNR, GE Spectral Width, MD Spectral Width, GE Non-Meteorological Mask, and MD Non-Meteorological Mask for the two different KAZR modes: GE (general sensitivity) and MD (moderate sensitivity). — Time-height plots show Ka-Band ARM Zenith Radar (KAZR) general sensitivity (GE) and moderate sensitivity (MD) mode reflectivity, signal-to-noise ratio, spectral width, and echo classification mask for October 22, 2023, at the North Slope of Alaska atmospheric observatory. The plots for MD mode highlight the sidelobes above cloud top. All figures in the announcement are from Marqi Rocque, Pacific Northwest National Laboratory.

The Atmospheric Radiation Measurement (ARM) User Facility has released its first set of characterized and corrected Ka-Band ARM Zenith Radar (KAZR) data from the Eastern North Atlantic (ENA), North Slope of Alaska (NSA), and Southern Great Plains (SGP) fixed-location atmospheric observatories. These KAZR data span a five-year period (2020–2024) and are b1-level, meaning they underwent calibration, correction, and quality control processes beyond ARM’s standard quality checks and corrections.

ARM’s fixed sites produce long-term data sets that can be used to improve understanding of atmospheric processes across various environments. The vertically pointing KAZR is a key ARM remote sensing instrument that can be used to investigate cloud and precipitation properties.

ARM staff completed two main tasks to produce the quality-controlled b1-level data from the fixed-site KAZRs. They cross-compared a1-level data from each KAZR with data from other ARM instruments and nearby radars to determine the KAZR reflectivity offsets. They also developed meteorological echo masks, which allow scientists to quickly remove background noise and clutter, including contaminated gates from insects (prevalent at the SGP) and sidelobes (prevalent at the NSA).

While the NSA and SGP both have first-generation KAZRs, the ENA has a second-generation KAZR (KAZR2). The KAZR2 has a different transmitter from the first-generation KAZR and operates with three modes instead of two.

A comparison of reflectivities from two radars (the SGP KAZR and the KVNX radar). The y-axis of the histogram on the left goes from 0 to 1200 counts, and the x-axis ranges from -10 to 30 dBZ reflectivity. The histogram on the right shows KAZR reflectivity on the y-axis from -10 to 30 dBZ, and the KVNX reflectivity on the x-axis goes from -10 to 30 dBZ as well. The legend of counts ranges from just below 10 up to just beyond 80. — Histograms for the 2020–2024 period show nonprecipitating ice cloud reflectivity from the Southern Great Plains observatory’s KAZR and the KVNX (Vance Air Force Base, Oklahoma) WSR-88D Doppler weather surveillance radar.

A stack of three plots showing KAZR general sensitivity (GE), moderate sensitivity (MD), and precipitation sensitivity (PR) mode reflectivity from a height range of 0 to 5 km and times from 0000 to 0100 UTC. The dBZ legend for all three plots goes from below -40 up to just beyond 20 dBZ. — Time-height plots provide GE, MD, and precipitation sensitivity (PR) mode reflectivity from the Eastern North Atlantic observatory’s second-generation KAZR (KAZR2) on October 16, 2022.

The corrected and characterized 2020–2024 data are available now in CfRadial format for the KAZR general sensitivity (GE) and moderate sensitivity (MD) modes at the NSA and SGP, and for the KAZR2 GE, MD, and precipitation sensitivity (PR) modes at the ENA.

More information about the data, including the radar analysis and mask development, can be found in the fixed-site KAZR b1-level data processing technical report.

Currently, ARM plans to release KAZR/KAZR2 b1-level data from the fixed sites every year for the previous year. More information is available in the latest ARM radar plan.

Access the KAZR GE and MD b1-level data and the KAZR2 GE, MD, and PR b1-level data in the ARM Data Center. (To download the data, first create an ARM account.)

For questions or to report data issues, please contact the ARM radar team.

To cite the NSA and SGP KAZR data, please use doi:10.5439/1615726 for GE mode and doi:10.5439/1615486 for MD mode.

To cite the ENA KAZR2 data, please use doi:10.5439/2589318 for GE mode, doi:10.5439/2589319 for MD mode, and doi:10.5439/2589320 for PR mode.

# # #

ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.