Characterized, Calibrated Fixed-Site KAZR Data Available for 2025

Published: 10 April 2026

Time-series plots illustrate reflectivity differences between the Ka-Band ARM Zenith Radar (KAZR) general sensitivity (GE) and moderate sensitivity (MD) modes at the Eastern North Atlantic (ENA), North Slope of Alaska (NSA), and Southern Great Plains (SGP) atmospheric observatories during 2025. The means are shown in the red dashed lines, and averages across each period are included on each subplot. The ENA plot says mean1 GE-MD = -2.4 dB and mean2 GE-MD = -1.6 dB. The NSA plot says mean GE-MD = -0.3 dB, and the SGP plot says mean GE-MD = 0.2 dB. — Time-series plots illustrate reflectivity differences between the Ka-Band ARM Zenith Radar (KAZR) general sensitivity (GE) and moderate sensitivity (MD) modes at the Eastern North Atlantic (ENA), North Slope of Alaska (NSA), and Southern Great Plains (SGP) atmospheric observatories during 2025. The means are shown in the red dashed lines, and averages across each period are included on each subplot. All figures in this data announcement were created by Marqi Rocque, Pacific Northwest National Laboratory.

The Atmospheric Radiation Measurement (ARM) User Facility has released characterized and corrected Ka-Band ARM Zenith Radar (KAZR) data for all of 2025 from its Eastern North Atlantic (ENA), North Slope of Alaska (NSA), and Southern Great Plains (SGP) fixed-location atmospheric observatories. These KAZR data 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 under variable environmental conditions. The vertically pointing KAZR is a key ARM remote sensing instrument that can be used to investigate cloud and precipitation properties.

As they did for the first set of fixed-site KAZR b1-level data, which covered the years 2020 through 2024, ARM staff completed two main tasks to produce the quality-controlled b1-level data for 2025. 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.

Six time-height plots of SGP KAZR GE and MD reflectivity, censor mask, and classification mask highlight the insects in the boundary layer (or biota, as indicated in the classification mask plots) on September 5, 2025. — Time-height plots of SGP KAZR GE and MD reflectivity, censor mask, and classification mask highlight the insects in the boundary layer (or biota, as indicated in the classification mask plots) on September 5, 2025.

The corrected and characterized 2025 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 2025 fixed-site KAZR b1-level data processing technical report.

Currently, ARM plans to process and release fixed-site KAZR/KAZR2 b1-level data on a yearly basis.

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.