MICROphysicS of COnvective PrEcipitation (MICROSCOPE)

该项目将通过解决对流云中降水的微物理问题来改进对强对流降雨的预报。作为对流降水实验(COPE)的一部分，对微物理的研究第一次被嵌入到一个项目中，该项目包括对流云更大尺度的动力学。COPE将把这项微物理研究与英国严重对流天气事件的系统尺度动力学联系起来。COPE还将提供一个天气系统模拟方案，这将使人们更好地了解天气系统、流域尺度上的降雨预报。天气预报模型目前的分辨率为1.5公里，这有助于改进对流地点和时间的预报。然而，正如博斯卡斯尔事件(Golding等人，2005年)所强调的那样，定量降水预报仍然很差。这在一定程度上是由于缺乏关于对流云中冰粒成核、暖雨过程以及二次冰粒的产生速度和随后的降水粒子增长的知识。然而，高的局部积累是降水强度(降水的微物理)和持续时间(汇聚线上细胞的组织和相互作用)的结果。后一个问题和更大范围的问题将在COPE的其他部分解决。显微镜有两个关键部分。第一个问题涉及一个基本问题：冰核(IN)是如何在云中形成冰粒的，特别是在高温下？第二个问题是降水：降水粒子是如何形成的？产生和发展的速度是多少？显微镜将通过以下方式解决解释积云中初级冰粒产生的挑战。*我们将使用FAAM 146飞机在地面和边界层测量气溶胶粒子的性质，特别是土壤和生物材料。*将测量液滴尺寸分布的演变，可能存在过冷雨滴，以及第一批冰粒的形成，飞机已经配备了新的仪器，可以明确地探测和表征小冰粒(SID，2DS，CAS-DPOL)。多普勒雷达将提供第一次降水回波的位置和时间、空气运动和粒子类型的测量。为了解释降水的产生和发展，过程模式和NWP模式的结果将与夹带过程、暖雨过程的发展、冰粒通过扩散生长成长为降水粒子、雨滴冻结成颗粒、二次生产过程的繁殖和结圈的观测结果进行比较。比较将通过在不断增加的高度进行多次穿透来实现，测量粒子在空间和时间上的分布以及云的热力学和动力学，并通过获得关于粒子的信息和来自双极化雷达的反射率回波的增加速率来实现。由英国气象局领导的显微镜的最后一步是将新的信息纳入到数值天气预报模型中，并与项目期间收集的数据进行测试。

This project will improve predictions of severe convective rainfall by addressing the problem of the microphysicsof precipitation in convective clouds. For the first time, study of the microphysics is embedded in aproject that includes the larger-scale dynamics of convective clouds, as part of the COnvective PrecipitationExperiment (COPE). COPE will connect this microphysical study with the system-scale dynamics of severeconvective UK weather events. COPE will also provide a programme of weather-system modelling, which willbring the microphysical understanding through to the improved prediction of rainfall at the weather-system, orcatchment scale.Weather forecast models are now run at resolutions of 1.5 km, which has helped to improve the predictionof the location and timing of convection. However, quantitative precipitation forecasts are still often poor ashighlighted in the Boscastle event (Golding et al., 2005). This is due in part to the lack of knowledge about thenucleation of ice particles in convective clouds, the warm rain process, and the rates of production of secondaryice particles and the subsequent growth of precipitation particles. However, high local accumulations were theresult of both intensity (microphysics of precipitation) and duration (organisation of and interaction between cellsalong the convergence line) of precipitation. The latter issue and wider-scale problem will be addressed in otherparts of COPE.There are two key parts to MICROSCOPE. The first concerns a fundamental problem: how do ice particlesform in clouds as a result of ice nuclei (IN), particularly at high temperatures? The second concerns precipitation:how do precipitation particles form and what are the rates of production and development? MICROSCOPE willaddress the challenge of explaining the production of primary ice particles in cumulus clouds, in the followingways.* We will make measurements of the properties of the aerosol particles, particularly soils and biologicalmaterial, on the ground and in the boundary-layer with the FAAM 146 aircraft.* Measurements will be made of the evolution of the droplet size distribution, the possible presence ofsupercooled raindrops and the formation of the first ice particles with carefully-guided penetrations of theaircraft that has been equipped with new instruments that can detect and characterise small ice particlesunambiguously (SID, 2DS, CAS-DPOL).* The dual-polarisation, Doppler radars will provide measurements of the location and time of the first precipitationechoes, the air motions and the types of particles.In order to explain the production and development of precipitation, process model and NWP model resultswill be compared to observations of the entrainment process, the development of the warm rain process, thegrowth of ice particles into precipitation particles by diffusional growth, the freezing of raindrops into graupelparticles, multiplication by secondary production processes, and riming. The comparisons will be achieved bymaking multiple penetrations at increasing altitudes measuring the particle size distributions in space and timeas well as the thermodynamics and dynamics of the cloud, and by obtaining information about the particles andthe rate of increase of the reflectivity echo from the dual-polarisation radar.The final step of MICROSCOPE, that will be led by the Met Office, is to incorporate the new information intoNWP models and to test against the data gathered during the project.