Evolution of microphysical structure of a subtropical squall line observed by a polarimetric radar and a disdrometer during OPACC in Eastern China

Abstract

The evolution of the microphysical structures of a subtropical squall line observed during the Observation, Prediction and Analysis of Severe Convection of China (OPACC) field campaign in Eastern China is documented in this paper. The data collected from a C‐band, polarimetric Doppler radar (reflectivity Z, differential reflectivity ZDR, and specific differential phase KDP) and a disdrometer are used to investigate the variations of microphysical characteristics within the convective region during the formative, intensifying, and mature stages of the squall line. The microphysical characteristics of the squall line are noticeably different among these three stages. When the squall line develops from the formative stage to the mature stage, its radar‐derived drop size distribution (DSD) in the convective region evolves from continental‐like convection to more maritime‐like convection. Contrary to previous studies, the DSD characteristics of a convective line may not be simply locked to a geographical location but varied extensively throughout its life cycle. The polarimetric radar‐derived liquid water content below the freezing level in the convective region is 3 times higher than the ice water content above the freezing level. This, in conjunction with a low cloud base (~0.68 km) and a high freezing level (~5 km), indicates a deep warm cloud layer and the dominance of the warm rain process within this squall line.

VDRAS and Polarimetric Radar Investigation of a Bow Echo Formation After a Squall Line Merged With a Preline Convective Cell

“…K DP is mainly influenced by the presence of liquid water over snow or ice; hence, it could be considered as a good indicator of the amount of liquid water within a radar sample volume (Bringi & Chandrasekar, 2001). Based on the characteristics of these polarimetric variables, microphysical processes could be inferred (e.g., Balakrishnan & Zrnic, 1989; Bringi et al, 1984; Wen et al, 2017; Zhang et al, 2006). These polarimetric variables will be used in conjunction with the VDRAS analysis to interpret the microphysical processes of this MFBE event.…”

“…The National Center for Atmospheric Research (NCAR) four‐dimensional variational Doppler radar analysis system (VDRAS) (Sun & Crook, 2001) has been used by researchers to analyze severe weather events to alleviate the limitations inherited in the radar observations (e.g., Sun & Zhang, 2008; Sun et al, 2010; Z He et al, 2018). In addition, polarimetric radar has recently been widely used to investigate microphysical characteristics of mesoscale convective systems (e.g., Chang et al, 2014; Homeyer & Kumjian, 2014; Wen et al, 2017). This study is the first to use VDRAS analysis in conjunction with polarimetric radar data to investigate the formation and evolution of a MFBE before and after a SL merged with a preline convective cell (CC) in China.…”

Statistical Characteristics of Raindrop Size Distribution in the Monsoon Season Observed in Southern China

“…what is more, it should be noted that there are other empirical µ-Λ relationships proposed based on the disdrometer observations of DSD due to the variabilities of µ-Λ relationship across different location and climatic regimes [44][45][46][47]. Therefore, the Z-R relationship should be localized in southern China.…”

Rain Microstructure Parameters Vary with Large-Scale Weather Conditions in Lausanne, Switzerland

“…For example, topography influences the interaction between rain forming processes in orographic rain [27][28][29]. In addition, rain DSD varies within the stages of squall lines [16,30]. It also varies in convective versus stratiform rain, continental versus maritime rain, and warm versus cold rain [24,31,32].…”