XPRECIPRADAR

The X-band precipitation radar (XPRECIPRADAR) for the Surface Atmosphere Integrated Field Laboratory (SAIL) campaign near Crested Butte, Colorado, is a scanning Doppler weather radar operating at X-band frequency of 9.4 GHz. It has dual-polarization capabilities, facilitating the transmission and reception of electromagnetic waves in both horizontal and vertical polarizations. The XPRECIPRADAR functions in a simultaneous transmit and receive (STAR) mode. The radar transmitter is a magnetron with 9 kW peak power per channel, and the receiver is similar to the radars used in CASA systems. As a high-resolution radar system, the XPRECIPRADAR has the ability to differentiate targets with a separation of over 60 meters.

The polarimetric variables collected by this radar include radar reflectivity factor at horizontal polarization (Z_h), differential reflectivity (Z_dr), Doppler radial velocity (V), spectral width (W), differential propagation phase shift (ψ_dp), and correlation coefficient between H and V channels (ρ_hv).  The signal-to-noise ratio (SNR) and normalized coherent power (NCP) are also stored in the radar data files.  All the variables are archived in netCDF format in the radar’s native polar coordinates. The dual-polarization measurements facilitate correction for attenuation of the electromagnetic signals due to propagation medium, estimation of summer and winter precipitation, and identification of different hydrometeor species within precipitation systems. Furthermore, the presence of the X-band scanning radar system for the Study of Precipitation, the Lower Atmosphere and Surface for Hydrometeorology (SPLASH), which is close to the ARM SAIL site, allows for the retrieval of dual-Doppler velocity fields.