Airborne Studies in the North Dakota Thunderstorm Project

在深度对流风暴中如何产生冰雹已经研究了好几年，但仍然存在许多问题。众所周知，冰雹是在小冰粒周围开始生长的，这些小冰粒被称为冰雹胚胎。过去十年的研究结果引起了人们对强风暴中一个被称为“馈线细胞”的区域的关注。这些是在主风暴单体附近形成的小型对流云，最终被主对流单体吸收（“馈入”）。据推测，至少在某些类型的冰雹中，这些喂养细胞是最终长成大冰雹的胚胎的主要生产者。美国国家科学基金会将与国家海洋和大气管理局合作，参与一项研究冰雹的实地计划。这个项目被称为北达科他州雷暴项目，将在1989年夏天举行。作为这项研究工作的一部分，首席研究员打算研究胚胎产生的两个方面。首先，使用原位飞机测量，将研究馈线细胞的微物理特性。这将包括在饲养细胞中植入人工冰核的实验，以研究过早成核对微物理过程的影响。第二个研究领域将集中在被称为细尺度反射率模式的现象上。这些是雷达回波增强的区域，被认为是冰雹胚胎的来源。通过直接感知，校长计划调查这样一个假设，即这些确实是胚胎高度集中的地区，这些胚胎经常进入产生大冰雹的风暴区域。//

How hail is produced in deep convective storms has been studied for several years, but many questions still remain. It is well-known that hailstones begin their growth around small ice particles which are referred to as hailstone embryos. Results over the last decade have drawn attention to an area in severe storms known as feeder cells. These are small convective clouds that form near the main storm cell and eventually are absorbed ("feed") into the main convective cell. It is speculated that, at least in some types of hailstorms, these feeder cells are the main producers of the embryos that eventually grow into large hail. In conjunction with the National Oceanic and Atmospheric Administration, the National Science Foundation will participate in a field program to study hailstorms. This project, known as the North Dakota Thunderstorm Project, will be held during the Summer of 1989. As part of this research effort, the Principal Investigator intends to study two aspects of embryo production. First, using in situ aircraft measurements, the microphysical characteristics of feeder cells will be investigated. This will include experimental seeding with artificial ice nuclei in the feeder cells to investigate the effects of premature nucleation on microphysical processes. The second area of investigation will focus on a phenomenon known as fine scale reflectivity patterns. These are areas of enhanced radar echo return and have been thought to be a source of hailstone embryos. Through direct sensing, the Principal plans to investigate the hypothesis that these are indeed areas of high concentration of embryos and that these embryos often find their way into the regions of the storm where large hail is produced. //