X-Band Polarmetric Doppler Weather Radar (XPOL)

XPol is a compact, transportable polarimetric weather radar. A photograph shows an XPol system delivered to the US National Center for Atmospheric Research (NCAR) in 2012.

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Based on a modified marine radar RF unit, the XPol system achieves high performance at a low cost. XPol  is specifically designed to sample backscatter from precipitation over an area of approximately 70 km x 70 km.  XPol collects reflectivity, Doppler velocity data,  key polarimetric radar parameters,  to characterize clouds and precipitation.

The measured polarimetric radar data is automatically post-processed and displayed with Titan/Hawkeye software (developed by NCAR)  to provide real-time meteorological data products (Z, Vel, σvel, Zdr, Φdp, Kdp, ρhv). The Hawkeye software package also provides hydrometeor classifications and automatic warnings for storms, hail and heavy rain.

Xpol Features

• 25 kW peak power, 0.1% duty cycle magnetron.

• 1.8 m diameter dual polarization antenna (1.4 deg. beamwidth).

• Air conditioned RF unit for all-weather operation.

• Equal power V/H polarization on transmit, separate receiver channels for simultenious reception of the V and H polarized backscattered field.

• 15-150 m selectable range resolution.

• PC-based 16-bit 2 channel digital receiver.

• Digital coherent-on-receive for Doppler measurements.

• Pulse-pair or full-spectrum operating and measurement mode.

• Data products include reflectivity, Doppler, ZDR, Kdp, rho_hv.


Example Data


Xpol single pol radar reflectivity factor – Zh (top) and differential reflectivity – Zdr (upper middle) PPI images in snow.

Xpol Doppler velocity (lower middle) and Rho_hv (bottom) PPI images in snow.PPI_RHOhvPPI_Vel