A Z(DR) Column Detection Algorithm to Examine Convective Storm Updrafts

作者：Snyder Jeffrey C^*; Ryzhkov Alexander V; Kumjian Matthew R; Khain Alexander P; Picca Joseph

来源：Weather and Forecasting, 2015, 30(6): 1819-1844.

DOI：10.1175/WAF-D-15-0068.1

Observations and recent high-resolution numerical model simulations indicate that liquid water and partially frozen hydrometeors can be lofted considerably above the environmental 0 degrees C level in the updrafts of convective storms owing to the warm thermal perturbation from latent heating within the updraft and to the noninstantaneous nature of drop freezing. Consequently, upward extensions of positive differential reflectivity (i.e., Z(DR) >= 1 dB)-called Z(DR) columns-may be a useful proxy for detecting the initiation of new convective storms and examining the evolution of convective storm updrafts. High-resolution numerical simulations with spectral bin microphysics and a polarimetric forward operator reveal a strong spatial association between updrafts and Z(DR) columns and show the utility of examining the structure and evolution of Z(DR) columns for assessing updraft evolution. This paper introduces an automated Z(DR) column algorithm designed to provide additional diagnostic and prognostic information pertinent to convective storm nowcasting. Although suboptimal vertical resolution above the 0 degrees C level and limitations imposed by commonly used scanning strategies in the operational WSR-88D network can complicate Z(DR) column detection, examples provided herein show that the algorithm can provide operational and research-focused meteorologists with valuable information about the evolution of convective storms.

• 出版日期2015-12