Helicopter-borne measurements of small-scale processes in shallow cumulus convection over Barbados

本研究旨在研究大气气溶胶粒子、小尺度云动力学、粒子数大小分布和信风积云的辐射特性之间的复杂相互作用。直升机载平台“ACTOS”将用于测量巴巴多斯的气象参数和气溶胶和云的特性。测量将在云内外进行，具有高空间分辨率。ACTOS将首次携带小型CCNc（云凝结核计数器）和新开发的气溶胶表征快速仪器。与飞机测量相比，高空间和时间分辨率，加上直升机飞行的低速度，将能够详细检查单个小型信风积云及其夹带区域。由于这些区域不断混合，它们对云的发展（液滴大小分布）以及对气溶胶的改变（云处理，例如颗粒吸湿性的变化）都很重要。这也会影响云层及其周围环境的光学特性，为了捕捉到这一点，将利用直升机下方的仪器进行辐射测量。通过结合不同的方面，特别是通过研究不同大气气溶胶的影响，我们的目标是更好地描述信风积云的早期阶段，从而能够在数值（气候）模式中更详细地描述这种云类型。这些拟议的活动被纳入一项长期测量计划，该计划将持续两年，并由MPI汉堡公司实现（包括HALO飞机上的遥感和测量）。

The project proposed here aims at examining the complex interactions between atmospheric aerosol particles, small scale cloud dynamics, particle number size distributions, and radiative properties of trade wind cumulus clouds. The helicopter borne platform ’ACTOS’ will be used to measure meteorological parameters and properties of aerosol and clouds at Barbados. Measurements will be done in- and outside of clouds, with a high spatial resolution. For the first time, ACTOS will carry an adapted small CCNc (Cloud Condensation Nuclei counter) and newly developed fast instrumentation for aerosol characterization. Compared to aircraft measurements, the high spatial and temporal resolution, together with the low speed at which a helicopter flies, will enable a detailed examination of individual small trade wind cumuli and of their entrainment regions. Due to the ongoing mixing in these regions, they are important for the development of the cloud (droplet size distribution) as well as for modifying the aerosol (cloud processing, e.g. a change in particle hygroscopicity). This then also influences the optical properties of the cloud and its surroundings, and to capture this, radiation measurements will be done with instruments being positioned beneath the helicopter. By combining the different aspects, and particularly by examining the influence of different atmospheric aerosols, we aim at obtaining a better description of the early stages of trade wind cumuli, enabling a more detailed description of this cloud type in numerical (climate-) models. These proposed activities are embedded into a long term measurement program that will last for two years and that is realized by the MPI Hamburg (including remote sensing and measurements on the HALO aircraft).