Correction of Radar Reflectivity From Gap-Filling X-Band Radar Observations

Based on the insensitivity of the specific differential phase ( ${K}_{\text {DP}}$ ) to path-integrated attenuation (PIA), partial beam blockage (PBB), and wet radome (WR) issues, the bias of reflectivity ( $Z_{\textrm {H}}$ ) is corrected for X-band gap-filling radars. The ${K}_{\text {DP}}$ – $Z_{\textrm {H}}$ relationship established using the raindrop size distribution (DSD) data collected by local disdrometers is considered in the correction procedure. The practical performance of this correction procedure is extensively evaluated during a severe rainfall event. The results show that: 1) this correction methodology can simultaneously address the PIA, PBB, and WR effects on $Z_{\textrm {H}}$ measurements at X-band frequency, and the corrected $Z_{\textrm {H}}$ at the X-band agrees very well with DSD-derived $Z_{\textrm {H}}$ and its C- and S-band counterparts and 2) radar quantitative precipitation estimates (QPEs) based on $Z_{\textrm {H}}$ are significantly improved after the correction in both the PBB-affected and PBB-unaffected areas. The applications of corrected $Z_{\textrm {H}}$ and the improved radar QPE can improve the gap-filling capability of X-band radars for surrounding C- and S-band radar observations.