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

地形云地面冰川形成播种的云微物理效应：研究老问题的新观测和建模工具

• 批准号: 1058426
• 负责人: Bart Geerts
• 金额: $ 49.33万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1058426&HistoricalAwards=false
• 关键词: Cloud; Microphysical; Effects; Ground; based

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.

这是一项实地活动，被称为ASCII(AGI播撒云影响调查)，旨在调查冰川成因播撒如何影响冬季地形云的云和降水物理。ASCII利用怀俄明州的一个可操作的云播撒项目，并将部署一台机载多普勒剖面云雷达和激光雷达。这个项目将来自新的但得到证实的仪器的数据分析与高分辨率的云和气溶胶分辨率模拟结合在一起，以评价模型，了解注入冰核如何影响相互竞争的微物理过程，并评估上游条件(湿度、温度、稳定性、冰核和云凝结核浓度)如何影响地面冰川成因播撒对云特性和地面降水的影响。它还研究了在混合相地形云中可能对降水的形成起重要作用的两个过程，即边界层湍流和地表诱导的冰启动。智力上的优点：证实降水增加是极其困难的，部分原因是与信号的大小相比，自然降水云系中存在高水平的“噪声”。然而，在过去的二十年里，已经开发出新的工具来更有效地研究云播撒的影响，特别是地面地形云的冰川播撒。一方面，有了新的观测工具，特别是机载云雷达和激光雷达，使人们能够详细查看复杂地形上方的过程，那里是大多数自然水流星增长发生的地方。另一方面，气溶胶和云过程数值模拟的巨大进步现在使冰核播撒过程的模拟成为可能。可以对模型输出进行处理，以便模拟可以直接与复合雷达和激光雷达数据进行比较。这项研究不仅涉及冰生云增雨效果的实际问题，而且还涉及更广泛的问题，即云活动气溶胶浓度如何影响云的降水效率，从而影响气候系统的潜热强迫和辐射热强迫。后一个问题非常复杂，因此可以通过相对可控的实验来解决，例如引发冰川的云播撒。广泛的影响：播云一直是最广泛使用的有意影响天气的方法，主要目的是增加降水。值得注意的是，尽管开展了一系列有针对性的实地活动，并对处理自然云和降水过程的实地工作进行了更强有力的实验控制，但播云在增加降水方面的有效性仍然不确定。尽管如此，播撒云层以增加降雨量仍然是一项蓬勃发展的商业活动，这只是指出了考虑到缺水地区的用水成本，这一点具有很高的潜在效益。我们相信，该项目将为地形云中注入冰核如何影响云特性和地面降水提供新的线索。这项实地工作将培训几名研究生掌握大气测量技术。