Physical Meanings of "Cave Channel" in Strong Convective Storm with Its Application

Xu Huanbin; Tian Liqing

Vol.19, NO.3, 2008

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Xu Huanbin, Tian Liqing. Physical meanings of 'cave channel' in strong convective storm with its application. J Appl Meteor Sci, 2008, 19(3): 372-379.

Citation:

Xu Huanbin, Tian Liqing. Physical meanings of "cave channel" in strong convective storm with its application. J Appl Meteor Sci, 2008, 19(3): 372-379.

Xu Huanbin, Tian Liqing. Physical meanings of 'cave channel' in strong convective storm with its application. J Appl Meteor Sci, 2008, 19(3): 372-379.

Citation:

Xu Huanbin, Tian Liqing. Physical meanings of "cave channel" in strong convective storm with its application. J Appl Meteor Sci, 2008, 19(3): 372-379.

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Physical Meanings of "Cave Channel" in Strong Convective Storm with Its Application

Xu Huanbin^1,2,
Tian Liqing²

1.
Beijing Institute of Applied Meteorology, Beijing 100029
2.
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029

Received Date: 2007-03-06
Rev Recd Date: 2008-01-28
Publish Date: 2008-06-30

Abstract

Abstract

Since the "cave channel"(CC) or "zero region"(ZR) structure is suggested, several papers are published on this title. The understanding of the physical meanings of CC or ZR is deepened by these papers, but in principle and application there are questions to answer or clear up, such as the conditions of formation of CC or ZR in strong storm, the analogous CC in rain-storm, why previous studies do not indicate the existence of CC, how to find CC structure in practical application etc. These questions are answered and the meanings are further understood by observation facts and numerical simulations. It is shown explicitly as the following. The CC or ZR structure is the results of the interaction between cloud's macro-flow field and cloud's micro-particle terminal velocities in nature. Some special structure of radar echo is BWER (bounded weak echo region), WER (weak echo region) or OE (overhang echo), it is the product of the interaction too. The interaction can play very important role only when the terminal velocity of particles is equivalent to the velocity of airflow. If the terminal velocity of particles relatively is too small or too large the effects of this interaction are very weak. The study of this interaction can deepen the understanding of the dynamical and physical meanings of the radar products, it is much necessary to find the characteristic criteria for now-casting of high-impact weather and in weather modification.
- interaction between the cloud's macro-dynamics and the cloud microphysics;
- now-casting;
- high-impact weather;
- weather modification;
- numerical simulation

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References(18)

Figures and Tables

图 1 “穴道”示意图 (a), 3个长成冰雹的粒子循环运行增长轨迹 (b), 1个长成冰雹并向“穴道”集中的大粒子循环运行增长轨迹的二维图 (垂直于剖面的格点坐标:y=22;*表示粒子出发位置; 虚线是上升气流速度等值线)(c), “零域”中上升气流速度及粒子平衡或平均位置 (d)

Fig. 1 (a) Schematic of "cave channal"(CC), (b) the 3D growth-travel trajectories of three large hailstones growing up, (c) the 2D growth-travel trajectories of a large hailstones concentrated to the "CC"(projection to the vertical cross section, y=22;* represents the starting loation; dashed lines present trajectories projected to the section), (d) the profile of verticle wind speed and particles at the equilibrium state with their terminal velocities respectively

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图 2 添加了相对水平风速为零的“零线”后Fleming雹暴垂直剖面图^[9]

Fig. 2 Vertical section showing features of the visual cloud boundaries of the Fleming storm^[9] with " zero line" of horizontal wind (ZLHW) analyzed by the author

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图 3 添加了悬挂回波轴线雹暴的反射率因子和估算的各种水凝物粒子群在云中分布的垂直剖面图^[10]

Fig. 3 Vertical section showing features of the reflectivity factor and the particles distribution of a hailstorm^[10]

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图 4 强对流云旋转对流流型的优选演化示意图

(a) 纯辐合, (b) 纯旋转, (c) 理想的强辐合和强旋转, (d) 实际和最优的强辐合和强旋转

Fig. 4 The evolution schematic of a strong convective and rotary airflow pattern which is optimal for the formation and maintenance of hailstorm

(a) full convergence, (b) full rotation, (c) strong convection and rotation in ideal, (d) strong convection and rotation in natural and in optimal

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图 5 冰雹云中长大成雹的340个粒子运行轨迹在模拟区间 (y=22~23) 粒子群运行增长轨迹分布 (a) 及三维运行增长轨迹 (b)

Fig. 5 Vertical cross sections through the main updraft and near CC, showing growth-travel trajectories of 340 hailstones growing up (y=22-23)(a), the 3D growth-travel trajectories near CC and through the main updraft (b)

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图 6 粒子末速比原有末速减少一半时的模拟, 在y=22~23区间内, 340个长成大粒子的增长运行轨迹在区间内的轨迹线段分布

Fig. 6 Same as in Fig.5a, but for the terminal velocities of partices equal the half as much as normal terminal velocity

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图 7 粒子群有末速时, “零域”邻区内的粒子群的平均尺寸 (a) 和粒子总数 (b) 随时步的变化

(m=n×30, n是积分时间步数, t=nΔT, ΔT=5 s)

Fig. 7 The evolution with time of the average diameter (a) and total number (b) of particles those locate within the volume of adjacent " CC"

(m=n×30, n is steps of integration, t=nΔT, ΔT=5 s)

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图 8 当粒子末速比原有末速减少一半时, “零域”邻区内的粒子群的平均尺寸 (a) 和粒子群总数 (b) 随时步的变化 (其他说明同图 7)

Fig. 8 Same as in Fig. 7, but for the terminal velocities of partices equal the half as much as normal terminal velocity

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