Instrument : X-Band Scanning ARM Precipitation Radar (XSAPR)

Instrument Categories
Cloud Properties

Picture of the X-band scanning ARM precipitation radar
Picture of the X-band scanning ARM precipitation radar

General Overview

The X-band scanning ARM precipitation radar (X-SAPR) is an X-band dual-polarization Doppler weather radar manufactured by Radtec, Inc. 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 will allow the provision to provide estimates of rainfall rates and identification of precipitation types. At the Southern Great Plains, there are three X-SAPRs surrounding the Central Facility, providing the capability to use multi-Doppler velocity retrievals to estimate wind fields.

The X-SAPR represents a new measurement capability for ARM.

Output Datastreams

  • xsaprhsrhi : X-SAPR Horizon-to-horizon Range-Height Indicator scan
  • xsaprppi : X-SAPR Plan Position Indicator scan
  • xsaprrhi : X-SAPR Range Height Indicator scan
  • xsaprsur : X-SAPR Surveillance scan
  • xsaprvad : X-SAPR Velocity-Azimuth Display scan
  • xsaprvpt : X-SAPR Vertical PoinTing scan

Primary Measurements

The following measurements are those considered scientifically relevant.


North Slope Alaska
NSAC1Browse DataCentral Facility, Barrow AK
Southern Great Plains
SGPI4Browse DataBillings, OK (SE X-band radar site, Intermediate / Auxiliary)
SGPI5Browse DataGarber, OK (SW X-band radar site, Intermediate / Auxiliary)
SGPI6Browse DataDeer Creek, OK (NW X-band radar site, Intermediate / Auxiliary)


Kevin Widener
(509) 528-9565

Nitin Bharadwaj
(509) 372-4267

Dan Nelson
(509) 375-6895

Iosif (Andrei) Lindenmaier
(509) 375--6802

Scott Collis
data analysis