Macro and micro physical structure characteristics of a low trough cold front cloud system in southern North China based on aircraft detection

doi:10.11755/j.issn.1006-7639(2023)-03-0450

Abstract

Abstract:

In order to carry out the cloud-seeding operation scientifically and accurately, the King-air 350 aircraft (no.3523) equipped with airborne particle measurement systems (PMS) entered the cloud for vertical and horizontal detection, and combined with FY-2F satellite, weather radar and other data, the microphysical structure of a low trough cold front stratified cloud system in southern North China on February 28, 2021 and the rainfall enhancement operation conditions were comprehensively analyzed. The results show that the precipitation cloud system is a medium and low cloud. The cloud top height observed by the aircraft is 6 014 m, the cloud top temperature is -17.7 ℃, the cloud bottom height is less than 582 m, the 0 ℃ layer height in the cloud is 1 300 m, the cloud body thickness is more than 5 400 m, the warm cloud thickness is more than 700 m, and the cold cloud thickness is more than 4 700 m. The cloud top height retrieved by satellite ranged from 5 to 6 km, which is consistent with the aircraft measurement result. The cloud top temperature retrieved by satellite ranged from -40 to -25 ℃, which is lower than the aircraft measurement result. The microphysical structure of the cloud system during the whole detection period is nonuniform. In the cold cloud, the second layer of ice water mixing zone (height ranged from 3 427 to 4 985 m, temperature ranged from -12.4 to -6.3 ℃) and the third layer of ice water mixing zone (height ranged from 5 449 to 6 014 m, temperature ranged from -18.3 to -15.3 ℃) appear large particle number concentration areas detected by cloud drop probe (CDP), the maximum values are 146.80 cm^-3 and 170.75 cm^-3, and the supercooled water content reach 0.12 g·m^-3 and 0.20 g·m^-3, respectively. The microphysical distribution of warm clouds is relatively uniform. The particle number concentration fluctuates at a height of 557-575 m and 844-866 m. The particle number concentration detected by CDP varies relatively large, while the concentration of particles detected by cloud imaging probe (CIP) and by the high volumeprecipitation spectrometer (HVPS) vary relatively small.The microphysical distribution of clouds within cold clouds is not uniform. The number concentration fluctuations of cloud particle within the cold cloud region are significant at a height of 3 603-3 617 m, 5 445-5 542 m, and 5 705-5 847 m, with multiple jumps.The particle spectral widths detected by CIP and HVPS in warm cloud region are narrower than those in cold cloud region, and the cold cloud is mainly composed of solid ice particles. In the early spring, the mixed stratiform clouds are prone to appear in the early stages of precipitation systems of low trough cold front stratiform clouds, and there is a certain amount of supercooled water near the cloud top. It is suitable to identify the rain-increasing timing and the precipitation-increasing location for sowing cold cloud catalysts. Artificial seeding has great potential for catalysis.

Key words: stratiform cloud, cloud microphysical structure, supercooled water, aircraft detection

摘要：

为科学精准地开展人工增雨作业，通过搭载机载粒子测量系统（Particle Measuring Systems， PMS）的空中国王350飞机（编号3523）入云进行垂直和水平探测，并结合FY-2F卫星、天气雷达等资料综合分析2021年2月28日华北南部一次低槽冷锋层状云系的微物理结构和增雨作业条件。结果表明：降水云系为中低云，飞机探测到云顶高度为6 014 m，云顶温度为-17.7 ℃，云底高度低于582 m，云内0 ℃层高度为1 300 m，云体厚度大于5 400 m，暖云厚大于700 m，冷云厚大于4 700 m;卫星反演的云顶高度为5~6 km，与飞机实测值较为一致，卫星反演的云顶温度为-40~-25 ℃，比飞机实测值偏低。整个探测时段云系微物理结构不均匀，冷云内第二层冰水混合区（高度3 427~4 985 m、温度-12.4~-6.3 ℃）和第三层冰水混合区（高度5 449~6 014 m、温度-18.3~-15.3 ℃）出现云滴谱探头（Cloud Droplet Probe， CDP）探测的粒子数浓度大值区，最大值分别为146.80、170.75 cm^-3，且过冷水含量分别达0.12、0.20 g·m^-3。暖云内云微物理分布较均匀，在557~575 m和844~866 m两个高度层粒子数浓度均存在波动，CDP粒子数浓度值变化相对较大，云粒子图像探头（Cloud Imaging Probe，CIP）和高体积降水粒子分光仪（The High Volume Precipitation Spectrometer，HVPS）探测的粒子数浓度变化较小。冷云内云微物理分布不均匀，冷云区内在3 603~3 617 m、5 445~5 542 m和5 705~5 847 m高度层云粒子数浓度起伏变化均较大且存在多次跃增。冷云区多为固态冰相粒子，暖云区CIP和HVPS粒子谱宽均比冷云区粒子谱窄。初春时期低槽冷锋层状云系降水系统前期易出现混合层状云，云顶附近存在一定量的过冷水，找准增雨时机、增雨部位适宜播撒冷云催化剂，人工引晶催化潜力较大。

关键词: 层状云, 云微物理结构, 过冷水, 飞机探测

CLC Number:

P426.51

FU Jiao, WANG Shuyi, DONG Xiaobo, WANG Xiaoqing, YANG Jiashuai, ZHANG Jiannan. Macro and micro physical structure characteristics of a low trough cold front cloud system in southern North China based on aircraft detection[J]. Journal of Arid Meteorology, 2023, 41(3): 450-462.

付娇, 王姝怡, 董晓波, 王晓青, 杨佳帅, 张健南. 基于飞机探测的华北南部低槽冷锋云系宏微物理结构特征[J]. 干旱气象, 2023, 41(3): 450-462.

Figures/Tables 13

Tab.1 Airborne instrumentations and their operational parameters

仪器名称	测量内容	测量范围（通道）	分辨率
CDP	云滴粒子数浓度、尺度谱、云中含水量等	2~50 μm （30通道）	各通道分辨率不同
CIP	大云滴、冰雪晶粒子数浓度、尺度谱、粒子图像等	25~1 550 μm （62通道）	25 μm
HVPS	冰雪晶、雨滴粒子数浓度、尺度谱、粒子图像等	150~19 200 μm （61通道）	各通道分辨率不同
CPI	云与降水粒子图像	10~2 000 μm （—）	2.3 μm
热线含水量仪	液态水含量和总含水量	0.05~3 g·m^-3（—）
AIMMS-20	经纬度
	海拔	0~13.7 km，精度18.3 m（—）	1 m
	温度	-50~50 ℃（—）	0.01 ℃

Tab.2 Flight overview

飞行时间	飞行高度/m（飞行方式）	飞行区域	机上宏观记录
10：20：51—10：30：30	844~866（水平飞行）^①	赵县	赵县高度限制东移
10：32：21—10：34：27	557~575（水平飞行）^②	赵县
10：34：31—11：24：14	582~6 781（盘旋上升）	赵县	因为限制高度，探测点向东偏移，5 942 m高度出云见蓝天
10：54：49—10：57：04	3 603~3 617（水平飞行）^③	赵县
11：09：57—11：17：04	5 445~5 542（水平飞行）^④	赵县、宁晋、柏乡
11：41：14—12：20：07	5 705~5 847（水平飞行）^⑤	高邑、柏乡、临城、赞皇

Fig.1 The time-height cross section of radar combination reflectivity along the flight trajectory （Unit： dBZ）（Numbers ①-⑤ correspond to Tab.2; Dotted boxes a and b stand for vertical detection period， the flying heights are 582-5 451 m and 5 451-6 781 m， respectively）

Fig.2 The 500 hPa geopotential height （the blue solid contours， Unit： dagpm）， temperature （the red dashed isolines， Unit： ℃） and wind field （wind vectors， Unit： m·s-1） at 08：00 on February 28， 2021

Fig.3 Vertical distribution of cloud particle number concentration detected by CDP （a）， CIP （b）， HVPS （c） and water content and temperature （d） over Zhaoxian （The red dotted boxes represent the strong seeding areas）

Fig. 4 The vertical variation of cloud particle spectrum by three types of probe （a） CDP，（b） CIP，（c） HVPS

Fig.5 Cloud top height （a， Unit： km） and cloud top temperature （b， Unit： °C） retrieved by FY-2F satellite at 11：00 on February 28， 2021 （The purple box area shows the position of the cloud observed by aircraft at 11：20）

Fig.6 The particle spectrum detected by three types of probe at different level （a） 5 802m，（b） 5 714 m，（c） 5 541 m，（d） 4 651 m，（e） 4 472 m，（f） 4 206 m，（g） 4 025 m，（h）1 387 m，（i） 1 249 m，（j） 997 m

Fig.7 The results detected by the aircraft at flying horizontally stage at a height of 844-866 m （a） particle number concentration detected by CDP，（b） particle number concentration detected by CIP，（c） particle number concentration detected by HVPS，（d） liquid water content，（e） particle spectrum detected by CDP，（f） particle spectrum detected by CIP，（g） particle spectrum detected by HVPS，（h） particle images detected by CPI

Fig.8 The results detected by the aircraft at flying horizontally stage at a height of 557-575 m （a） particle number concentration detected by CDP，（b） particle number concentration detected by CIP，（c） particle number concentration detected by HVPS，（d） liquid water content，（e） particle spectrum detected by CDP，（f） particle spectrum detected by CIP，（g） particle spectrum detected by HVPS，（h） particle images detected by CPI

Fig.9 The results detected by the aircraft at flying horizontally stage at a height of 3 603-3 617 m （a） particle number concentration detected by CDP，（b） particle number concentration detected by CIP，（c） particle number concentration detected by HVPS，（d） liquid water content，（e） particle spectrum detected by CDP，（f） particle spectrum detected by CIP，（g） particle spectrum detected by HVPS，（h） particle images detected by CPI

Fig.10 The results detected by the aircraft at flying horizontally stage at a height of 5 445-5 542 m （a） particle number concentration detected by CDP，（b） particle number concentration detected by CIP，（c） particle number concentration detected by HVPS，（d） liquid water content，（e） particle spectrum detected by CDP，（f） particle spectrum detected by CIP，（g） particle spectrum detected by HVPS，（h） particle images detected by CPI

Fig.11 The results detected by the aircraft at flying horizontally stage at a height of 5 705-5 847 m （a） particle number concentration detected by CDP，（b） particle number concentration detected by CIP，（c） particle number concentration detected by HVPS，（d） liquid water content，（e） particle spectrum detected by CDP，（f） particle spectrum detected by CIP，（g） particle spectrum detected by HVPS，（h） particle images detected by CPI

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