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

Active Instrument Locations

Facility Name Instrument Start Date
Billings, OK (Intermediate) 2010-12-14
Deer Creek, OK (Intermediate) 2010-12-17
Central Facility, Barrow AK 2011-06-24
Garber, OK (Intermediate) 2010-12-17


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Matsui T, B Dolan, T Iguchi, S Rutledge, W Tao, and S Lang. 2020. "Polarimetric Radar Characteristics of Simulated and Observed Intense Convective Cores for a Midlatitude Continental and Tropical Maritime Environment." Journal of Hydrometeorology, 21(3), 10.1175/JHM-D-19-0185.1.
Research Highlight


Kollias P, N Bharadwaj, E Clothiaux, K Lamer, M Oue, J Hardin, B Isom, I Lindenmaier, A Matthews, E Luke, S Giangrande, K Johnson, S Collis, J Comstock, and J Mather. 2019. "The ARM Radar Network: At the Leading-edge of Cloud and Precipitation Observations." Bulletin of the American Meteorological Society, 101(5), 10.1175/BAMS-D-18-0288.1.

Jackson R, S Collis, T Lang, and C Potvin. 2019. PyDDA: A new Pythonic wind retrieval package. In 18th Annual Scientific Computing with Python Confe, .

Schrom R and M Kumjian. 2019. "A probabilistic radar forward model for branched planar ice crystals." Journal of Applied Meteorology and Climatology, 58(6), 10.1175/JAMC-D-18-0204.1.

Lamer K, B Puigdomènech Treserras, Z ZHU, B Isom, N Bharadwaj, and P Kollias. 2019. "Characterization of Shallow Oceanic Precipitation using Profiling and Scanning Radar Observations at the Eastern North Atlantic ARM Observatory." Atmospheric Measurement Techniques, 12(9), 10.5194/amt-2019-160.

Wood R, G Zhang, N Hickmon, M Jensen, S Klein, R Leung, D Mechem, and P Zuidema. 2019. Atmospheric Radiation Measurement (ARM) User Facility ARM Mobile Facility Workshop Report. Ed. by Rolanda Jundt, Robert Stafford, U.S. Department of Energy Office of Science. DOE/SC-0197.

Oue M, P Kollias, A Shapiro, A Tatarevic, and T Matsui. 2019. "Investigation of observational error sources in multi-Doppler-radar three-dimensional variational vertical air motion retrievals." Atmospheric Measurement Techniques, 12(3), doi:10.5194/amt-12-1999-2019.
Research Highlight


Mechem D and S Giangrande. 2018. "The Challenge of Identifying Controls on Cloud Properties and Precipitation Onset for Cumulus Congestus Sampled during MC3E." Journal of Geophysical Research: Atmospheres, 123(6), doi:10.1002/2017JD027457.
Research Highlight

Schrom R and M Kumjian. 2018. "Bulk-Density Representations of Branched Planar Ice Crystals: Errors in the Polarimetric Radar Variables." Journal of Applied Meteorology and Climatology, 57(2), doi:10.1175/JAMC-D-17-0114.1.
Research Highlight

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