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

Instrument Categories
Cloud Properties

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
NSAC1 Browse DataCentral Facility, Barrow AK
Southern Great Plains
SGPI4 Browse Data Browse PlotsBillings, OK (Intermediate)
SGPI5 Browse DataGarber, OK (Intermediate)
SGPI6 Browse DataDeer Creek, OK (Intermediate)


Joseph Hardin
Pacific Northwest National Laboratory
(509) 375-2664

Dan Nelson
Pacific Northwest National Laboratory
(509) 375-6895

Iosif (Andrei) Lindenmaier
Pacific Northwest National Laboratory
(509) 375--6802

Bradley Isom
Pacific Northwest National Laboratory

Scott Collis
Argonne National Laboratory
data analysis

Alyssa Matthews
Pacific Northwest National Laboratory
data analysis

Nitin Bharadwaj
Pacific Northwest National Laboratory
(509) 372-4267