xsapr: X-Band Scanning ARM Precipitation Radar

The X-band scanning ARM precipitation radar (X-SAPR) is an X-band dual-polarization Doppler weather radar. The X-SAPR operates in a simultaneous transmit and receive (STAR) mode, meaning that the transmit signal is split so that power is transmitted on both horizontal and vertical polarizations at the same time. The X-SAPR transmitter is a 200 kW (peak power) magnetron. The receiver is based upon the Vaisala RVP-900 and runs Vaisala’s IRIS software.

In addition to the first three Doppler moments (reflectivity, radial velocity, and spectra width), the X-SAPR also provides differential reflectivity, correlation coefficient, and specific differential phases. The dual-polarization variables enable estimates of rainfall rates and identification of precipitation types. At the Southern Great Plains site, three X-SAPRs surround the Central Facility, allowing the use of multi-Doppler velocity retrievals to estimate wind fields.



  • Fixed
  • AMF1
  • AMF2
  • AMF3

Related Publications


Kalesse H, G DeBoer, A Solomon, M Oue, M Ahlgrimm, D Zhang, M Shupe, E Luke, and A Protat. 2016. "Understanding Rapid Changes in Phase Partitioning between Cloud Liquid and Ice in Stratiform Mixed-Phase Clouds: An Arctic Case Study." Monthly Weather Review, 144(12), 10.1175/mwr-d-16-0155.1. ONLINE.

Wen G, M Oue, A Protat, J Verlinde, and H Xiao. 2016. "Ice particle type identification for shallow Arctic mixed-phase clouds using X-band polarimetric radar." Atmospheric Research, 182, 10.1016/j.atmosres.2016.07.015.

Helmus JJ and SM Collis. 2016. "The Python ARM Radar Toolkit (Py-ART), a Library for Working with Weather Radar Data in the Python Programming Language." Journal of Open Research Software, 4(1), 10.5334/jors.119.

van Lier-Walqui M, AM Fridlind, AS Ackerman, S Collis, J Helmus, DR MacGorman, K North, P Kollias, and DJ Posselt. 2016. "On polarimetric radar signatures of deep convection for model evaluation: Columns of specific differential phase observed during MC3E." Monthly Weather Review, 144(2), 10.1175/mwr-d-15-0100.1. ONLINE.

Wang Y, B Geerts, and Y Chen. 2016. "Vertical structure of boundary layer convection during cold-air outbreaks at Barrow, Alaska." Journal of Geophysical Research: Atmospheres, 121(1), 10.1002/2015jd023506.


Mechem DB, SE Giangrande, CS Wittman, P Borque, T Toto, and P Kollias. 2015. "Insights from modeling and observational evaluation of a precipitating continental cumulus event observed during the Midlatitude Continental Convective Clouds Experiment field campaign." Journal of Geophysical Research: Atmospheres, 120(5), 10.1002/2014jd022255.


Giangrande SE, S Collis, A Theisen, and A Tokay. 2014. "Precipitation Estimation from the ARM Distributed Radar Network during the MC3E Campaign." Journal of Applied Meteorology and Climatology, 53(9), 10.1175/jamc-d-13-0321.1.


Giangrande SE, R McGraw, and L Lei. 2013. "An Application of Linear Programming to Polarimetric Radar Differential Phase Processing." Journal of Atmospheric and Oceanic Technology, 30(8), 10.1175/jtech-d-12-00147.1.

Mather JH and JW Voyles. 2013. "The Arm Climate Research Facility: A Review of Structure and Capabilities." Bulletin of the American Meteorological Society, 94(3), 10.1175/bams-d-11-00218.1.

Chandrasekar V and J Hardin. 2013. Integrated Framework for Retrievals in a Networked Radar Environment and Error Characterization of Retrievals. Presented at 4th Atmospheric System Research (ASR) Science Team Meeting. Potomac, MD.

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