The Cloud Microphysical Effects of Ground-based Glaciogenic Seeding of Orographic Clouds: New Observational and Modeling Tools to Study an Old Problem

这是一个被称为ASCII（AgI播种云影响调查）的实地活动，旨在调查冰川播种如何影响冬季地形云的云和降水物理学。 ASCII利用了怀俄明州的一个云播种项目，并将部署一个机载多普勒测云雷达和激光雷达。 该项目将新的经验证的仪器的数据分析与高分辨率的云和气溶胶解析模拟相结合，以评估模型，了解冰核注入如何影响相互竞争的微物理过程，并评估上游条件如何（湿度、温度、稳定性，冰核和云凝结核浓度）影响地面冰川催化对云特性和地面降水的影响。 它还研究了两个过程，可能是重要的降水形成的混合相地形云，即边界层湍流和表面引起的冰initiation.Intellectual优点：验证降水增强已被证明是极其困难的，部分原因是高水平的“噪音”在自然降水云系统相比，信号的大小。 然而，在过去的二十年中，新的工具已经开发出来，以更有效地研究云催化的影响，特别是基于地面的地形云的冰川催化。 一方面，有新的观测工具，特别是机载测云雷达和激光雷达，可以详细观察复杂地形上方的过程，大多数水凝物的自然生长都发生在那里。 另一方面，气溶胶和云过程数值模拟的巨大进步现在使模拟冰核播种过程成为可能。可以处理模型输出，以便模拟可以直接与复合雷达和激光雷达数据进行比较。 这项研究不仅与通过冰川云催化增雨的实际问题有关，而且与云活跃气溶胶的浓度如何影响云的降水效率，从而影响气候系统的潜热和辐射热强迫的更广泛的问题有关。 后一个问题非常复杂，因此可以通过相对受控的实验（如冰川云催化）有效地解决。更广泛的影响：云催化是最广泛使用的人工影响天气方法，主要目的是增加降水。 值得注意的是，尽管进行了一系列有针对性的实地活动，而且与处理自然云和降水过程的实地工作相比，实验控制更强，但播云在增加降水方面的有效性仍然不确定。尽管如此，播云以增加降水仍然是一项蓬勃发展的商业活动，考虑到水资源有限地区的水成本，这只是指出了潜在的高效益。 我们相信，该项目将为地形云中的冰核注入如何影响云的特性和地表降水提供新的线索。 实地工作将对几名研究生进行大气测量技术方面的培训。

This is a field campaign, referred to as ASCII (AgI Seeding of Clouds Impact Investigation), to investigate how glaciogenic seeding affects the cloud and precipitation physics of winter orographic clouds. ASCII takes advantage of an operational cloud seeding project in Wyoming and will deploy an airborne Doppler profiling cloud radar and lidar. This project combines the analysis of data from new yet proven instruments with high-resolution cloud- and aerosol-resolving simulations, in order to evaluate the model, to understand how competing microphysical processes are affected by the injection of ice nuclei, and to assess how upstream conditions (moisture, temperature, stability, ice nuclei and cloud condensation nuclei concentrations) influence the impact of ground-based glaciogenic seeding on cloud properties and surface precipitation. It also examines two processes that may be important in precipitation formation in mixed-phase orographic clouds, i.e. boundary-layer turbulence and surface-induced ice initiation.Intellectual merit: Verification of precipitation enhancement has proven to be extremely difficult, in part because of a high level of "noise" in naturally precipitating cloud systems, compared to the magnitude of the signal. Yet in the past two decades new tools have been developed to more effectively study the impact of cloud seeding, in particular ground-based glaciogenic seeding of orographic clouds. On the one hand, there are new observational tools, in particular airborne cloud radars and lidars, allowing a detailed view of processes just above the complex terrain, where most of the natural hydrometeor growth occurs. On the other hand, dramatic advances in the numerical modeling of aerosol and cloud processes now enable the simulation of the ice nuclei seeding process. Model output can be processed such that simulations can be compared directly with composite radar and lidar data. This study is relevant not only to the practical question of efficacy of precipitation enhancement by means of glaciogenic cloud seeding, but also to the much broader question about how the concentration of cloud-active aerosol affects the precipitation efficiency of clouds, thereby affecting the latent and the radiative heat forcing of the climate system. The latter question is very complex, and thus can be productively addressed by means of relatively controlled experiments such as glaciogenic cloud seeding.Broader Impacts: Cloud seeding has been the most widely practiced method of advertent weather modification, mainly with the purpose of enhancing precipitation. It is remarkable that notwithstanding a series of targeted field campaigns and the stronger experimental control than in field work dealing with natural cloud and precipitation processes, the effectiveness of cloud seeding in enhancing precipitation remains uncertain. Nonetheless, seeding clouds to enhance precipitation remains a thriving commercial activity, which simply points to the high potential benefit, given the cost of water in water-limited regions. We are confident that the project will shed new light into how the injection of ice nuclei in orographic clouds affects cloud properties and surface precipitation. The field work will train several graduate students in atmospheric measurement techniques.