Science. 1975 Jun 20;188(4194):1171-7. doi: 10.1126/science.188.4194.1171.
Relatively simple atmospheric electrical instrumentation carried on a small aircraft constitutes a flexible and sensitive system for detecting organized convection. Data can be obtained close to the sea surface, and low-velocity flight enhances the spatial resolution. With a slow-flying airplane or powered glider, it may be possible to trace the circulation of individual convection cells and to investigate the trajectory of air which forms cumulus clouds, one of the major unsolved problems in tropical meteorology. Since space charge near the ocean surface was found on some days to be organized on a horizontal scale equivalent to the cumulus cloud scale, this suggests that some of the air which forms maritime cumulus clouds may come from within a few meters of the ocean and that atmospheric electrical instrumentation may have the potential for tracing air from the sea surface to the clouds. Although the atmospheric electrical instrumentation technique described here cannot be used for direct measurement of air velocity, it may be possible to develop model that can be used to calculate air velocities from electric field data. Even though with the technique described here it is not possible to make direct measurements of wind velocity, airborne electric field records can provide useful information about convection by delineating patterns in the wind field and structural features of thermals (rising bodies of relatively warm air) and by making possible the remote detection of thermals (29). Future plans include attempting to trace interfaces between adjacent roll vortices from the sea surface through the depth of the mixed layer (i) by flying the aircraft parallel to the wind so as to nullify the horizontal electric field (measured between wing-tip probes) while ascending and descending along the interface between adjacent roll vortices and (ii) by measuring vertical and horizontal potential gradient variations at different flight levels (30). The sensitivity of atmospheric electrical instrumentation to the top of the mixed layer and structure within it can be used to explore another important problem in boundary layer convection-why convective cloud cover and oceanic rainfall are greater at night than during the day(31). Workers in atmospheric electricity have long recognized that their domain is strongly controlled by turbulence in the lower atmosphere, and many have believed that the most effective use of atmospheric electrical techniques to assist meteorological research would be in studying exchange processes. Reiter [see (8)] effectively extended atmospheric electrical studies of boundary layer phenomena through a height range by mounting instruments on cable cars traveling between the valley floor and mountain tops in the Alps. The airborne measurements described here extend this approach. Relating the electrical structure of the atmosphere to its dynamic structure poses an interesting problem which may contribute to our understanding of the atmosphere.
相对简单的大气电学仪器安装在小型飞机上，构成了一个灵活而敏感的系统，用于探测有组织的对流。可以在靠近海面的地方获取数据，低速飞行可以提高空间分辨率。使用低速飞行的飞机或动力滑翔机，可能可以追踪单个对流单元的循环，并研究形成积云的空气的轨迹，这是热带气象学中的一个主要未解决问题。由于在某些日子里发现海洋表面附近的空间电荷在水平尺度上与积云尺度相当有组织，这表明形成海洋积云的一些空气可能来自海面几米以内，大气电学仪器可能有潜力从海面追踪到云层。尽管这里描述的大气电学仪器技术不能用于直接测量空气速度，但有可能开发出一种可以从电场数据计算空气速度的模型。尽管这里描述的技术不可能直接测量风速，但机载电场记录可以通过描绘风场模式和热（相对温暖空气的上升体）的结构特征来提供有关对流的有用信息，并通过远程检测热来提供有用信息（29）。未来的计划包括尝试从海面通过混合层的深度追踪相邻滚流涡旋之间的界面（i）通过使飞机与风向平行飞行，从而消除水平电场（在翼尖探头之间测量），同时沿着相邻滚流涡旋之间的界面上升和下降，以及（ii）通过在不同飞行高度测量垂直和水平位势梯度变化（30）。大气电学仪器对混合层顶部及其内部结构的敏感性可用于探索边界层对流中的另一个重要问题——为什么夜间对流云覆盖率和海洋降雨量比白天大（31）。大气电学工作者早就认识到，他们的领域受到低层大气湍流的强烈控制，许多人认为，最有效地利用大气电学技术来协助气象研究将是研究交换过程。赖特[见（8）]通过在阿尔卑斯山的山谷底部和山顶之间运行的缆车安装仪器，有效地扩展了大气电学对边界层现象的研究范围。这里描述的机载测量扩展了这种方法。将大气的电结构与动力结构联系起来提出了一个有趣的问题，这可能有助于我们对大气的理解。
