Characteristics of X-, Ka-, and W-band Radar Parameters from Precipitating Clouds in the Arctic

Recent studies have reported unique characteristics of Arctic precipitation and clouds. For this study we used the X-band Scanning ARM Precipitation Radar (XSAPR) and Ka- and W-band Scanning ARM Cloud Radars (KASACR and WSACR) installed at Barrow, Alaska, and analyzed their reflectivities for two Arctic frontal snow cases: one case with liquid-cloud layers (mixed-phase clouds) and the other without. The presence of liquid-cloud layers is determined from the lidar backscattering coefficients and circular depolarization ratios as measured by the High Spectral Resolution Lidar (HSRL) and Doppler spectra measured by the Ka-band ARM Zenith Radar (KAZR). For the mixed-phase cloud case, the HSRL measured relatively large backscattering coefficients and small circular depolarization ratios at height ranges between 0.2 km to 0.7 km and 1.0 km to 1.5 km. The Doppler spectra from the KAZR were bi-modal at all heights below 2.0 km. These HSRL measurements and Doppler spectra suggest the presence of distinct liquid-clouds layers below a height of 2.0 km. The radar reflectivities from the WSACR strongly decreased where these liquid-cloud layers were present as compared to the KASACR. The rate of decrease of the WSACR's reflectivity reached up to 1.2 dB km^-1 at an elevation angle of 2° in a region where reflectivities from the KASACR were approximately 11 dBZ. XSAPR and KASACR reflectivities were comparable. For the glaciated case, differences in reflectivities among the three radars were smaller than the mixed-phase clouds case. KaSACR reflectivities attained values up to 10 dBZ and were slightly larger than those from the other two radars. We will discuss the characteristics of radar reflectivities and other parameters measured by these radars at different frequencies for these two precipitating systems in the Arctic.