A Polarimetric Analysis of Ice Microphysical Processes in Snow, using Quasi-Vertial Profiles

This study implements a new QVP methodology to investigate the microphysical evolution and significance of intriguing winter polarimetric signatures and their statistical correlations. QVPs of transitional stratiform and pure snow precipitation are analyzed using WSR-88D S-band data, alongside their corresponding environmental thermodynamic HRRR model analyses. QVPs of K_DP and Z_DR are implemented to demonstrate their value in interpreting elevated ice processes. Several fascinating and repetitive signatures are observed in the Z_DR and K_DP QVPs, in the DGL and at the tops of clouds. The most striking feature is maximum Z_DR (up to 6 dB) in the DGL occurring near the -10 dBZ Z_H contour within low K_DP and during shallower and warmer cloud tops. Conversely, maximum K_DP (up to 0.3° km^-1) in the DGL occurs within low Z_DR and during taller and colder cloud tops. Essentially, Z_DR and K_DP in the DGL are anti-correlated and strongly depend on cloud top temperature. Analyses also show correlations indicating larger Z_DR within lower Z_H in the DGL, and larger K_DP within greater Z_H in the DGL. The high Z_DR regions are likely dominated by growth of a mixture of highly oblate dendrites and/or hexagonal plates, or prolate needles. Regions of high K_DP are expected to be overwhelmed with snow aggregates and crystals with irregular or nearly spherical shapes, seeded at cloud tops. Furthermore, QVP indications of hexagonal plate crystals within the DGL are verified using in-situ microphysical measurements, demonstrating the reliability of QVPs in evaluating ice microphysics in upper regions of winter clouds.