著者

CUI Ye RUAN Zheng WEI Ming LI Feng GE Runsheng

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-028, (Released:2020-02-24)

被引用文献数

3

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Data from the continuous observations of 4 shallow snow events (echo top < 8 km) and 2 deep events (> 10 km) were obtained by the C-band vertically pointing radar with frequency modulation continuous wave technology (VPR-CFMCW) with extremely high resolution during the winter of 2015-2016 in middle latitudes of China. Generating cells (GCs) were found near the cloud top in each event. Reflectivity (Z), radial velocity (Vr), the vertical gradient of Z (dZ/dh, h is the vertical distance) and Vr (dVr/dh) showed different vertical distribution characteristics between the upper GC and lower stratiform (St) regions. The fall streaks (FSs) associated with GCs were embedded in the St regions. In the deep events, the proportions of GC regions were slightly larger, but the average contributions to the growth of Z (33 %) were lower than those in the shallow events (42 %). The average dZ/dh were usually 2-3 times larger inside GCs and FSs compared to outside. Bimodal Doppler spectra were used to establish the relationships between the Z and the reflectivity-weighted particle fall speed (Vz) for the 2 regions. The vertical air velocity (Wa) and Vz were then retrieved. The results show that both updraft and downdraft were alternately observed in GC regions. GC locations usually accompanied strong upward air motions, with average speeds mostly distributed around 1.2 m s−1, while downward air motions often appeared between GCs. In the St regions, the speeds of Wa were mainly within 0.5 m s−1. The upper areas of the St regions consisted primarily of weak upward motions, while weak downward motions dominated the lower areas. There was no apparent difference in Wa inside and outside the FSs. The average Vz was slightly larger inside GCs and FSs compared to outside, with the differences of 0.1-0.3 m s−1 and 0.2-0.4 m s−1 respectively.

著者

CUI Ye RUAN Zheng WEI Ming LI Feng GE Runsheng HUANG Yong

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-032, (Released:2021-01-21)

被引用文献数

1

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This study applied the C-band vertically pointing radar with frequency-modulation continuous-wave technology to obtain the continuous observation data of four shallow and two deep snow events during the winter of 2015-2016 in the midlatitudes of China. Generating cells (GCs) were found near the echo tops in every event. The ice particle number concentration (N), ice water content (IWC), and median mass diameter (Dm) retrieved from radar Doppler spectra were used to analyze the microphysical properties in the snow clouds. The clouds were divided into upper GC and lower stratiform (St) regions according to their vertical structure. The fall streaks (FSs) associated with GCs were embedded in the St regions. In the GC regions, the N values in shallow events were smaller compared with deep events, while Dm and IWC were larger. In the St regions, N decreased compared with the GC regions, while the Dm and IWC increased, implying the existence of aggregation and deposition growth. The growth of particle size and mass mainly occurred in the St regions. The increases of N were usually observed near −5°C accompanied by bimodal Doppler spectra, which might be caused by ice multiplication. The average ratios of the median N, Dm, and IWC inside GCs to those outside GCs are 2, 1.3, and 2.5 respectively for shallow events, with 1.7, 1.2, and 2.3 respectively for deep events. These values were basically the same as those for the FSs, implying the importance of GCs to the enhanced ice growth subsequently found in FSs. The larger values of N, Dm, and IWC inside GCs could be related to the upward air motions inside GCs. The first Ze–IWC relationship suitable for snow clouds in the midlatitudes of China was also established.