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强对流降雨的预测。作为对流降水实验（COPE）的一部分，微物理研究首次被嵌入到一个项目中，该项目包括对流云的更大规模动力学。COPE将把这一微物理研究与英国几个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建模项目，该项目将把对微物理的理解转化为对天气系统或集水区尺度上的降雨的改进预测。天气预报模型现在以1.5公里的分辨率运行，这有助于改善对流的位置和时间的预测。然而，定量降水预报仍然很差，这在波士顿事件中尤为突出（Golding et al., 2005）。这在一定程度上是由于对对流云中冰粒的成核、暖雨过程、二次冰粒的产生速度和随后降水颗粒的增长缺乏了解。然而，高局地累积是降水强度（降水微物理）和持续时间（辐合线上单体的组织和相互作用）共同作用的结果。后一个问题和更大范围的问题将在会议的其他部分讨论。显微镜有两个关键部分。第一个问题涉及到一个基本问题：特别是在高温下，冰核是如何在云中形成冰粒的？第二个问题涉及降水：降水颗粒是如何形成的，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子产生的挑战。*我们会用FAAM 146飞机在地面和边界层测量气溶胶颗粒的性质，特别是土壤和生物物质。*将对液滴大小分布的演变、可能存在的过冷雨滴和第一个冰粒的形成进行测量，飞机配备了新的仪器，可以明确地探测和表征小冰粒（SID, 2DS, CAS-DPOL）。*双偏振多普勒雷达将提供首次回波的位置和时间、空气运动和粒子类型的测量数据。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颗粒、雨滴冻结成霰颗粒、二次生产过程的倍增和雾凇的观测结果进行比较。通过在增加的高度进行多次穿透，测量颗粒大小在空间和时间上的分布以及云的热力学和动力学，并通过双偏振雷达获得有关颗粒和反射率回波增加率的信息，可以实现比较。由英国气象局领导的“显微镜”项目的最后一步是整合intoNWP模型的新信息，并对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.