First Characterized and Corrected BNF Radar Data Now Available

Published: 6 July 2026

The Atmospheric Radiation Measurement (ARM) User Facility has released its first set of characterized and corrected radar data from the Bankhead National Forest (BNF) atmospheric observatory in northern Alabama. These data are b1-level, meaning they underwent correction and quality control processes beyond ARM’s standard quality checks and corrections.

ARM has produced b1-level data for the following BNF radars:

the second-generation C-Band Scanning ARM Precipitation Radar (CSAPR2)
the Ka-Band Scanning ARM Cloud Radar (KASACR)
the second-generation Ka-Band ARM Zenith Radar (KAZR2)
the X-Band Scanning ARM Cloud Radar (XSACR).

These radars are located at three sites in and around the forest, collecting data to help researchers understand how the forest canopy structure, surface fluxes, and regional meteorology influence the formation and evolution of boundary-layer clouds and precipitation systems. The KAZR2 operates within the forest at the BNF main site, the KASACR and XSACR are located about 16.5 kilometers northeast of the KAZR2, and the CSAPR2 is another 21 kilometers northeast of the KASACR and XSACR.

The KAZR2 operates with three modes—general sensitivity (GE), moderate sensitivity (MD), and precipitation sensitivity (PR)—to collect data on cloud dynamics and properties. CSAPR2 observations provide details on the microphysical properties and life cycle of convective clouds, while data from the KASACR and XSACR are useful for information on cloud microstructures.

Four panels, stacked two by two, show the Bankhead National Forest (BNF) radar performance as a percentage of available data per hour for the second-generation Ka-Band ARM Zenith Radar (KAZR2) from November 2024 through June 2025 and for the second-generation C-Band Scanning ARM Precipitation Radar (CSAPR2), Ka-Band Scanning ARM Cloud Radar (KASACR), and X-Band Scanning ARM Cloud Radar (XSACR) from April through June 2025. The CSAPR2, KASACR, and XSACR were mostly operational except for an offline period over several days in June 2025. The KAZR2 had a period of being offline in February 2025 but was otherwise mostly operational the whole time. — These panels show the Bankhead National Forest (BNF) radar performance as a percentage of available data per hour for the second-generation Ka-Band ARM Zenith Radar (KAZR2) from November 2024 through June 2025 and for the second-generation C-Band Scanning ARM Precipitation Radar (CSAPR2), Ka-Band Scanning ARM Cloud Radar (KASACR), and X-Band Scanning ARM Cloud Radar (XSACR) from April through June 2025. Figure was created by Marqi Rocque, Pacific Northwest National Laboratory.

To produce the quality-controlled b1-level data, ARM staff applied reflectivity offsets and meteorological echo masks to each of the radar data sets.

Staff estimated the reflectivity offsets by cross-comparing ARM radar data with values from the Huntsville National Weather Service WSR-88D (Weather Surveillance Radar) and disdrometer measurements from the BNF main site.

The meteorological echo masks allow scientists to quickly remove background noise and clutter.

Given the dual-polarization nature of the CSAPR2 and XSACR, these radar data sets also include differential reflectivity corrections, specific differential phase calculations, and attenuation estimates.

Radar display images and plots arranged in a four-by-four square show how the four Bankhead National Forest radars each observed different types of weather cases. — This figure highlights different cases observed by the four BNF radars. From left to right are isolated cells, a quasi-linear convective system (QLCS), a tornado-producing supercell, and light drizzle observed by the CSAPR2 (top row); XSACR (second row); KASACR (third row); and KAZR2 (bottom row). The CSAPR2 and XSACR panels share the same reflectivity color bar, while the KASACR and KAZR2 share a different color bar. XSACR range rings are shown on the CSAPR2 panels (white dashed circles) and KASACR range rings are shown on the CSAPR2 and XSACR panels (white solid circles). The KAZR2 data are displayed as height-time plots, and the vertical dashed lines correspond to the scanning radar images above. Figure was created by Rocque and Alyssa Matthews, Pacific Northwest National Laboratory.

The KAZR2 b1-level data cover the beginning of operations in mid-November 2024 through June 2025. The CSAPR2, KASACR, and XSACR data cover an intensive operational period during the April–June 2025 convective season, when the scanning radars consistently performed the same scans.

The corrected and characterized BNF radar data sets are available now in CfRadial format.

More information about the data, including the radar analysis, related corrections, and other known data quality issues (e.g., CSAPR2 beam blockage and azimuth flips), can be found in the BNF b1-level radar data processing report for spring 2025.

Subsequent releases of more recent b1-level data are scheduled toward the end of fiscal year 2026.

Access the BNF b1-level radar 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 data, please use the following DOIs:

CSAPR2: doi:10.5439/2001313
KASACR: doi:10.5439/1877338
KAZR2: doi:10.5439/2589318 (GE mode), doi:10.5439/2589319 (MD mode), and doi:10.5439/2589320 (PR mode)
XSACR: doi:10.5439/2001296.