Polarimetric and dual-Doppler observations of Kelvin-Helmholtz waves during a winter storm

Abstract: Kelvin-Helmholtz waves were observed in the displays of a variety of radar platforms including the S-band WSR-88D KTLX, the polarimetric WSR-88D testbed KOUN, and the X-band, polarimetric CASA radars, during stratiform precipitation occurring in a winter storm in central Oklahoma. The waves were manifest as oscillations in radial velocity, reflectivity, and spectrum width in all radars, and also were apparent in the differential reflectivity and cross-correlation coefficient fields of the polarimetric instruments. The entire life-cycle of the waves was captured in the KTLX and KOUN data and is examined herein. Dual-Doppler analyses synthesized between KOUN and KTLX illuminate the three-dimensional wind field structure and circulations associated with these waves, and clarify how the wind field is related to the radar features. It is hypothesized that microphysical processes associated with ice multiplication and local thermal perturbations are responsible for the polarimetric and reflectivity signatures observed.