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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Horizontal structure of the electric field in the stratiform region of an Oklahoma mesoscale convective system - art. no. 4225
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Horizontal structure of the electric field in the stratiform region of an Oklahoma mesoscale convective system - art. no. 4225

机译：俄克拉何马州中尺度对流系统的层状区域中电场的水平结构-艺术。没有。 4225

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1] This analysis combines vertical electric field components E-z observed by two research aircraft flying horizontally at two levels, with vertical soundings of thermodynamic parameters and E-z made by five balloons, to produce a quasi-three-dimensional view of the space charge distribution in the trailing stratiform cloud region behind a mesoscale convective system (MCS) that developed in central Oklahoma late in the afternoon of 2 June 1991. The balloons were launched serially at one-hour intervals from two sites separated by 80 km along a north-south line as the MCS moved eastward, yielding two east-west time-height cross-sections of the E-z structure within the quasi-steady state trailing stratiform region behind the MCS. The balloon measurements are consistent with a vertical stack of five rearward- and downward-sloping horizontal sheets of charge of alternating polarity, beginning at the bottom with a negative charge layer below the 0degreesC level and a positive layer near the 0degreesC level. This structure persisted for more than 2 hours. The two aircraft flew back and forth along a north-south line through the balloon launch sites during the balloon launch period. Aircraft measurements demonstrated that the vertical electric field (E-z) at constant altitude varied in the north-south direction. The peak magnitudes of E-z deduced from the airborne instrument systems agreed with the magnitudes deduced from the balloon measurements at the aircraft altitudes of 4.5 km and 5.8 km AGL. Rapid reversals in polarity of E-z with peak magnitude >50 kV m(-1) observed by the aircraft at 4.5 km, just above the 0degreesC level, confirms the thin concentrated positive charge layer observed there by balloons and suggests that this charge layer is undulating above and below 4.5 km altitude, at least in the north-south direction. Microphysically, this layer contained large aggregates and pockets of low cloud liquid water concentration. At the 5.8 km level, the polarity of E-z was always positive but the magnitude varied from zero to 25 kV m(-1). Aircraft-observed E-z at both altitudes varied on horizontal scales of similar to10 km or greater at both levels, suggesting that the charge density derived using the one-dimensional infinite-layer Gauss's law approximation applied to the balloon soundings of E-z is valid in this study. These observations show that layers of charge can persist for hours as they advect rearward in a storm-relative sense, possibly due to continuing in situ charge separation, and/or due to weak dispersion, slow recombination and slow settling of charge attached to low mobility low terminal velocity ice hydrometeors. [References: 18
机译：1]该分析结合了两架水平飞行的两架研究飞机观察到的垂直电场分量Ez，热力学参数的垂直测深和五个气球的Ez值，从而得出了空间电荷分布的准三维视图。 1991年6月2日下午在俄克拉荷马州中部发展的中尺度对流系统（MCS）后面的层状云区域。气球从北向南沿80公里的两个站点以一个小时的间隔连续发射MCS向东移动，在MCS后面的准稳态尾随层状区域内产生了Ez结构的两个东西时高剖面。气球测量结果与垂直堆叠的5个交替交替向后倾斜和向下倾斜的水平电荷片垂直堆叠，该电荷片的底部始于0℃以下的负电荷层和0℃附近的正电荷层。这种结构持续了两个多小时。在气球发射期间，两架飞机沿着南北线来回穿过气球发射场。飞机测量结果表明，恒定高度的垂直电场（E-z）在南北方向上变化。从机载仪器系统推导出的E-z峰值幅度与在航空器高度为4.5 km和5.8 km AGL的气球测量值推导出的幅度一致。飞机在4.5 km处观测到的Ez极性迅速反转，峰值幅度> 50 kV m（-1），刚好高于0°C水平，证实了气球在那里观察到的薄而集中的正电荷层，表明该电荷层是起伏的至少在南北方向上高于和低于4.5 km。从微观上讲，该层包含大的聚集体和低云状液态水浓度的囊袋。在5.8 km的水平上，E-z的极性始终为正，但幅度从零到25 kV m（-1）不等。在两个高度上飞机观测到的Ez在两个水平上的水平尺度上变化都相似于10 km或更大，这表明使用一维无限层高斯定律近似法得出的Ez气球测深得出的电荷密度在本研究中是有效的。这些观察结果表明，电荷层在向风暴相对的方向向后平移时可以持续数小时，这可能是由于持续的原位电荷分离和/或由于弱迁移，弱迁移，缓慢的重组和缓慢的电荷沉降所造成的。低终速度冰水凝结物。 [参考：18

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