UK ICE-D

本研究的目的是确定沙漠沙尘如何影响对流云和层云中冰粒的成核以及云的降水和冰川作用的后续发展。灰尘被认为是地球系统中一个关键的气溶胶颗粒，主要是因为灰尘颗粒本身，以及从它们的来源运输时经过化学和可能的生物修饰的颗粒，被认为是全球意义上最重要的冰核，而且因为灰尘颗粒被运输到地球的许多地方。从气溶胶粒子的分布来预测云中冰粒子的大小分布的开始和随后的演变是大气科学中最重要的问题之一。它是NERC高级战略目标“了解和预测我们的地球如何运行”的基础，因为缺乏对这些过程的了解导致全球模式在处理辐射与冰和混合相云的相互作用以及降水发展的方式上存在不确定性。它们还导致数值天气预报（NWP）模式的不确定性，而数值天气预报与NERC战略目标“对环境危害的恢复力”有关。拟议中的研究旨在通过测量世界上最大的沙漠沙尘来源之一附近的气溶胶和云粒子来解决这个问题。测量很难进行，这就是为什么以前从未在该地区进行过如此详细的测量。现在有可能做到这一点，因为仪器能够确定气溶胶颗粒的化学和物理性质，飞机云物理仪器可以检测小冰粒，并且有一个移动双偏振雷达。英国云中冰-尘埃实验（UK Ice - d）是美英飞机和地面项目的一部分，该项目位于非洲塞内加尔海岸的佛得角，将于2015年（主要是英国）和2016年（主要是美国）举行。将在云周围的环境中进行测量，以描述气溶胶颗粒及其作为冰核和云凝结核的能力，并在云内进行测量，以确定颗粒对云特性的影响。对流云将被优先测量，但层云也将成为目标。在适当的海拔高度有高浓度尘埃和几乎没有尘埃存在的情况下进行观测。美国和英国飞机的可用性无意中提供了一个独特的机会，可以最大限度地对云进行抽样统计。地点和时间是从气候学研究中选择的，因为灰尘浓度通常很大，对流和层云也经常出现。此外，该地区的对流云非常重要，因为它们可以形成集群，导致热带大西洋的风暴和飓风。具体而言，英国ICE-D将在有和没有灰尘的日子里测量以下情况：*使用佛得角气溶胶容器中的仪器和bae146飞机测量地面上的气溶胶颗粒；*云滴、过冷雨滴、第一冰粒子和随着飞机发展的冰和降水粒子；*利用雷达测得过冷雨滴的高度、第一次降水回波的位置和时间，以及径向空气运动；*云的热力学和动力学及其与飞机的环境，在某种程度上也与雷达有关。模型结果将与起始温度和生长发育速率的观测结果进行比较。一系列模式，从气候模式到区域预报模式，再到明确的基于云物理过程的模式，将被用作预报工具和解释数据以及发展或改进参数化的工具。

The goal of this research is to determine how desert dust affects the nucleation of ice particles in convective and layer clouds and the subsequent development of precipitation and glaciation of the clouds. Dust is believed to be a critical aerosol particle in the Earth system mainly because the dust particles themselves, and particles that are chemically and possibly biologically modified as they are transported from their source, are believed to be the most important ice nuclei in a global sense and because dust particles are transported to many parts of the globe. Predicting the initiation and subsequent evolution of thesize distribution of ice particles in clouds from a distribution of aerosol particles is one of the most important problems in atmospheric science. It is fundamental to the NERC high-level strategy objective ``Understand and predict how our planet works'', because the lack of understanding of the processes causes uncertainty in the way global models treat the interaction of radiation with ice and mixed-phase clouds and the development of precipitation. They also cause uncertainty in Numerical Weather Prediction (NWP) models, which is concerned with the NERC strategy objective ``Resilience to environmentalhazards''. The proposed research aims to tackle this problem by making measurements of aerosols and cloud particles close to one of the largest sources of desert dust in the world. The measurements are difficult to make, which is why such detailed measurements have never been made in this region before. It is possible to do this now because the instruments are capable of determining the chemical and physical properties of aerosol particles, the aircraft cloud physics instruments can detect small ice particles, and there is a mobile dual-polarisation radar. The UK Ice in Clouds Experiment -- Dust (UK ICE-D) is part of the US-UK aircraft and ground-based project based in Cape Verde off the coast of Senegal, Africa to be held in 2015 (mainly UK) and 2016 (mainly US). Measurements will be made in the environment around the clouds to characterise the aerosol particles and their ability to act as ice nuclei and cloud condensation nuclei, and within the clouds to determine the influence of the particles on the cloud properties. Convective clouds will be measured as a priority, but layer clouds will also be targeted. Observations will be made when dust is present in high concentrations at appropriate altitudes and when almost no dust ispresent. The availability of the US and UK aircraft has inadvertently provided a unique opportunity to maximise the sampling statistics of the clouds. The location and time was selected from climatology studies because dust concentrations are often large and convective and layer clouds also occur frequently. In addition, the convective clouds in the region are known to be important since they can form clusters that lead to storms and hurricanes in the Tropical Atlantic.Specifically, UK ICE-D will make measurements on days with and without the presence of dust of the following:* Aerosol particles on the ground with the instruments in the aerosol container at Cape Verde and with the BAe 146 aircraft;* Cloud droplets, supercooled raindrops, the first ice particles and development of ice and precipitation particles with the aircraft;* The altitudes of the supercooled raindrops, the location and time of the first precipitation echoes, and the radial air motions using the radar;* The thermodynamics and dynamics of the clouds and their environment with the aircraft and to some extent the radar.Model results will be compared with the observations of the initiation temperatures and rates of growth and development. A spectrum of models ranging from climate through regional forecast models to explicit cloud physics process-based models, will be used as forecasting tools and as tools to interpret the data and to develop or improve parametrizations.