The enigma of spurious echoes:Enhancing phase transition height detection in shallow convective precipitation with GPM DPROA

The Global Precipitation Measurement(GPM)core satellite''s Dual-frequency Precipitation Radar(DPR)provides new insights into detecting solid-to-liquid phase transition heights of precipitation particles.However,significant anomalies can be found in the"binMixedPhaseTop"parameter within its official Level 2 data products during shallow convective precipitation events.Statistical analysis of the Yangtze and Huai River Basins from 2014to 2023 reveals that the anomaly rate for shallow convective precipitation is 64.94%,far exceeding those for convective(0.61%)and stratiform(0.48%)precipitation.Further investigation demonstrates that the warm-rain process characteristic of shallow convective systems lacks a distinct solid-to-liquid phase transition layer,leading to algorithmic misinterpretations.An improved identification algorithm for"binMixedPhaseTop"is proposed to address this problem.It incorporates additional checks to ensure that the phase-transition height is only identified when a melting layer is present,thereby preventing misjudgments and redundant computations.The enhanced version is validated against 10-year observations from South China(20142023),demonstrating 91%anomaly suppression through extreme deviation truncation.This study highlights the need for algorithm refinement to accurately detect phase-change heights in different precipitation types,thereby enhancing the reliability of the"binMixedPhaseTop"product for convective precipitation detection.