Sensor development for in-situ measurements of charge in non-thunderstorm clouds using small UAVs and free balloons

云是大气科学中最难以理解的现象之一。这部分是由于所涉及的微物理过程的复杂性，但也由于缺乏具有很高观测难度的原位测量的可靠数据。以往的研究表明，电荷存在于大多数云类型中，但其位置、大小和产生机制尚未得到很好的表征。目前的理论预测了电荷在非雷暴云中潜在的重要作用，它对云滴相互作用的影响，因此对大尺度云的性质，如高度、寿命甚至降雨的影响。然而，到目前为止，缺乏原位电荷和云测量阻碍了对这一问题的研究。因此，该项目旨在通过开发新型机载平台的新观测技术，通过产生新的电荷和云微物理测量数据集，研究电荷在非雷暴云中的作用。云微物理观测目前是在有人驾驶飞机上进行的，这种观测成本高，可实现的空间采样有限，而且受到人的生命危险因素的限制。为了获得现场云和电荷测量，该项目将利用无人机和自由气球的替代平台，这为更频繁的采样提供了机会，这是为了充分表征非雷暴云的可变性所必需的。由于此类平台的尺寸和重量限制，需要设计，集成和测试新的电荷和云传感器，该项目将开发。由于目前大气科学界缺乏这种仪器，研究结果可能会彻底改变云内测量的可用性，特别是在电测量方面。这项工作有可能对提高对云微物理过程的理解的能力产生强烈的积极影响，从而使更准确的天气和气候模式成为可能。研究的主要步骤是(a)研究适合云内电测量的小型无人机平台的设计要求（高空飞行、高有效载荷能力、低电噪声注入、远程自主）。(b)开发有效载荷传感器包（很可能是电场磨，云滴光谱表征的光学技术和热力学考虑的温度和湿度传感器）。(c)调查机载平台对电测量的影响，并提出减轻传感器干扰的建议。(d)利用已开发的传感器制作新的现场非雷暴电荷和云微物理数据集，并将结果与以前的地面和空中测量结果进行比较。

Clouds are some of the least well understood phenomena in atmospheric science. This is in part due to the complexity of microphysical processes involved, but also due to the lack of robust data from in-situ measurements which have a high observational difficulty. Previous research has shown that charge is present in most cloud types, but the location, magnitude and generation mechanisms are not well characterized. Current theory predicts a potentially important role for charge in non-thunderstorm clouds in terms of its effects on cloud droplet interactions, and therefore large scale cloud properties such as height, lifetime and even rainfall. However, lack of in-situ charge and cloud measurements have hampered investigation of this problem so far. This project therefore seeks to investigate the role of charge in non thunderstorm clouds by producing new data sets of charge and cloud microphysical measurements through the development of new observational techniques from novel airborne platforms.Cloud microphysical observations are currently performed from manned aircraft which are costly, limited in terms of spatial sampling achievable and are limited by human life risk factors. In order to obtain the in-situ cloud and charge measurements, this project will utilise the alternative platforms of UAVs and free balloons, which provide opportunities for much more frequent sampling, which is required in order to fully characterise the variability of non-thunderstorm clouds. Due to the limited size and weight constraints of such platforms, design, integration and testing of new charge and cloud sensors is required, which this project will develop. Due to the current lack of such instrumentation in the atmospheric science community the outcome of the research could revolutionize the availability of in-cloud measurements, particularly in respect to the electrical measurements. The work has potential for strong positive impact on the ability to improve the understanding of cloud microphysical processes and thus to allow for more accurate weather and climate modelling. The main steps of the research are (a) to investigate the design requirements for a suitable small UAV platform for in-cloud electrical measurements (high altitude flight, high payload capacity, low electric noise injections, long range autonomy). (b) development of payload sensor package (most probably an electric field mill, optical techniques for cloud droplet spectra characterization and temperature and humidity sensors for thermodynamic considerations). (c) investigate the effect of the airborne platforms on the electrical measurements and propose mitigation for sensor interference. (d) produce new data sets of in-situ non-thunderstorm charge and cloud microphysical data using the developed sensors and compare results with previous ground based and airborne measurements.