Collaborative Research: The Wasatch Hydrometeor Aggregation and Riming Experiment

模拟的风暴寿命和降水产生对降水形成和冷凝水去除的参数化速率非常敏感。先前的大量研究表明，我们提供准确天气预报的能力的致命弱点在于模式如何表示大量微物理参数化（BMPs），特别是当涉及到混合和冰相过程时。这里有两个核心问题：1)对于给定的气象情景，水流星的习性和颗粒直径（或面积）与颗粒质量和下落速度有何关系？2)风暴中水成物的习性、大小、质量和下降速度在聚集和形成过程中是如何演变的？用于天气模式的下一代bmp需要采用新的测量方法，这些方法必须能够详细描述水流星的形式、三维结构和下降速度，并以当地气象环境的详细信息为条件。过去对这些问题的研究受到了挑战，要么是需要在数学上理想化冰晶形状，要么是测量方法不精确，要么是由于需要人类直接参与现场测量而存在主观性因素。知识价值：该项目将通过前所未有的气象和微物理测量相结合，消除以往观测工作中的许多猜测。2011年至2012年冬季，瓦萨奇水文流星聚集和圈定实验（WASHARX）将以新开发的多角度雪花相机（MASC）为核心。这是一种潜在的变革性仪器，因为它将首次提供全自动的20 ìm-resolution多重立体彩色水成物摄影，并同时测量它们的下降速度。在盐湖城附近的瓦萨奇前线（Wasatch Front）的一个高海拔滑雪胜地的范围内，有两个这样的新仪器将被安装在一个陡峭的、受到高度保护的侧峡谷内。两个MASCs将垂直分开410米。这个观测系统还将伴随着沿着760米峡谷深度的气象测量，以及一个云滴大小分布探测器和北卡罗莱纳州立大学垂直指向的1.2厘米微降雨雷达。该项目的预期结果将是一个前所未有的数据集，将用于研究水流星下降速度关系及其由于风暴系统内聚集和边缘过程而产生的垂直演变。更广泛的影响：我们领域的科学进步经常依赖于新工具的广泛可及性。除了为未来天气和气候模型的整合提供新的bmp之外，这项研究还将有助于支持新仪器的科学开发（以及复制品的制造），我们打算为未来的科学实地项目提供这些仪器。事实上，为了科学研究、环境安全应用和公众利益，已经朝着商业化生产这种仪器迈出了初步步骤。该项目还具有广泛的教育成分。在当地滑雪场获得的3D立体图像将通过与Alta滑雪场合作开发的网站实时提供给教室和公众。最后，我们将与当地K-12级教师合作，开发将雪花形态与当地气象联系起来的模块。

Simulated storm lifetime and precipitation production is exquisitely sensitive to the parameterized rate of precipitation formation and condensate removal. Extensive prior research has shown that the achilles heel in our ability to provide accurate weather forecasts lies in how models represent bulk microphysics parameterizations (BMPs), particularly when it comes to mixed and ice phase processes. There are two core questions here:1) For a given meteorological scenario, how is hydrometeor habit and particle diameter (or area) related to particle mass and fallspeed?2) How do the relationships between hydrometeor habit, size, mass and fallspeed in a storm evolve due to aggregation and riming processes?The next generation of BMPs for weather models needs to be informed by new measurement methods that must be capable of detailed characterization of hydrometeor form, three-dimensional structure, and fallspeed, conditioned by detailed information about the local meteorological context. Past research into these problems has been challenged by either a necessity to mathematically idealize ice crystal shapes, imprecise measurement methods, or an element of subjectivity due to a need for direct human participation in field measurement.Intellectual merit:This project will remove much of the guesswork in prior observational efforts with an unprecedented combination of meteorological and microphysical measurements. For the winter of 2011-2012, the Wasatch Hydrometeor Aggregation and Riming Experiment (WASHARX) will have as its centerpiece the newly developed Multi-Angle Snowflake Camera (MASC). This is a potentially transformative instrument since it will provide, for the first time, fully-automated 20 ìm-resolution multiply-stereoscopic color photography of hydrometeors, along with concurrent measurement of their fallspeed. Within the bounds of a high-altitude ski resort along the Wasatch Front near Salt Lake City, two of these new instruments will be installed within a steep, highly protected side canyon. The two MASCs will be vertically separated by 410 m. This observing system will also be accompanied by meteorological measurements along the full canyon depth of 760 m, as well as a cloud droplet size distribution probe and the North Carolina State University's vertically-pointing 1.2 cm MicroRainRadar. The expected outcome of this project will be an unprecedented data set that will be used for studying hydrometeor fallspeed relationships and their vertical evolution due to aggregation and riming processes within a storm system.Broader impacts: Scientific progress in our field has regularly hinged on broad accessibility of new tools. In addition to providing new BMPs for future integration in weather and climate models, this study will help support scientific development of a new instrument (and manufacture of a replica) that we intend to make available for future scientific field programs. Indeed, initial steps have been made toward commercial production of this instrument for scientific research, environmental safety applications and public interest. The project also has a broad educational component. The 3D steroscopic images obtained at the local ski area will be made accessible in real-time to classrooms and the general public through a website developed in cooperation with Alta Ski Area. Finally, we will work with local K-12 level teachers to develop modules for relating snowflake form to local meteorology.