VOCALS: Comprehensive Studies of Marine Stratocumulus during VOCALS-REx Using Airborne Radar, Lidar, and In Situ Measurements

现在已经认识到毛毛雨是海洋层积云的一个共同特征，它对云甲板的热、水和气溶胶收支有重要影响。此外，对海洋层积云中尺度组织（通常在5 - 100 km尺度上）的分析表明，毛毛雨是连接中尺度组织和云微物理过程的关键过程。被认为是毛毛雨-气溶胶-云相互作用的结果，开放单体口袋（POCs）的形成导致了云组分和反照率的巨大变化，这对气候具有重要意义。虽然poc的形成是这些联系中最引人注目的例子，但它只是决定层积云特征的毛毛雨-气溶胶-云相互作用的众多表现之一。因此，迫切需要进行观测研究，以提供毛毛雨率和与毛毛雨直接相关的过程（如气溶胶颗粒的去除）的定量估计，并全面描述不同类型中尺度组织中的运动学、热力学和云微物理结构；这些可以用来研究毛毛雨-云的结构联系，并与数值模拟得到的结构进行比较。该项目将通过在VOCALS-REx （VAMOS海洋-云-大气-陆地研究区域实验）期间在NSF C-130飞机上部署一套仪器，为定量和定性需求做出贡献。测量将包括：雷达反射率和多普勒速度的垂直横截面、云底高度、云凝结核（CCN）、气溶胶和水流星大小光谱的测量。来自雷达的反射率横截面和垂直平面速度场将用于识别和表征层积云顶边界层内的中尺度结构，并通过使用条件采样方法，开发中尺度结构的复合描述。雷达横截面也将为NSF C-130上的其他测量提供背景。预期结果包括：定量估计（将纳入VOCLALS-REx综合数据集）：降水率（云底和海面）、云底和云顶高度、云下气溶胶和CCN光谱，以及毛毛雨导致的CCN去除率；利用中尺度结构的复合描述，将评估从未破碎到破碎的海洋层积云转变的可能机制。预计会产生两个更广泛的影响：首先，与其他VOCALS研究人员合作，VOCALS- rex的综合数据集将被汇编并提供给大气科学界。与其他VOCALS-REx研究人员一起，将根据云宏观物理特征开发云微物理过程的参数化。第二，将通过研究生培训发展协同使用雷达、激光雷达和现场观测方面的专门知识。

It is now recognized that drizzle is a common feature of marine stratocumulus clouds and that it has an important impact on the heat, water, and aerosol budgets of cloud decks. Additionally, analyses of mesoscale organization in marine stratocumulus clouds (typically on a scale of 5 - 100 km) show that drizzle is the key process linking mesoscale organization and cloud microphysical processes. The formation of pockets of open cells (POCs), which is believed to result from drizzle-aerosol-cloud interactions, results in large changes in cloud-fraction and albedo - properties of cloud decks that are significant for the climate. While the formation of POCs is the most dramatic example of these linkages, it is only one of many manifestations of drizzle-aerosol-cloud interactions that determine the characteristics of the stratocumulus layer. As such, there is a pressing need for observational studies that provide quantitative estimates of drizzle rates and of processes directly linked to drizzle (such as the removal of aerosol particles) and for a comprehensive depiction of the kinematic, thermodynamic, and cloud-microphysical structure within different types of mesoscale organization; these can be used to investigate drizzle-cloud structure linkages and for comparison with structures obtained from numerical simulations.This project will contribute to the quantitative and qualitative needs by deploying a suite of instruments on the NSF C-130 aircraft during VOCALS-REx (VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment). Measurements that will include: vertical cross-sections of radar reflectivity and Doppler velocity, measurements of cloud-base height, cloud condensation nuclei (CCN), aerosol, and hydrometeor size spectra. Reflectivity cross-sections and vertical-plane velocity fields from the radar will be used to identify and characterize mesoscale structures within the stratocumulus-topped boundary layer and, through the use of a conditional sampling approach, to develop a composite depiction of mesoscale structures. Radar cross-sections will also provide a context for other measurements made onboard the NSF C-130.Expected outcomes include: quantitative estimates, which will be incorporated into integrated VOCLALS-REx datasets, of: precipitation rate (cloud-base and sea surface), cloud-base and cloud-top heights, sub-cloud aerosol and CCN spectra, and the rate of CCN removal due to drizzle; an assessment of probable mechanisms underlying the transition from unbroken to broken marine stratocumulus will be made using the composite depictions of the mesoscale structures.Two broader impacts are expected: First, in collaboration with other VOCALS investigators, integrated datasets from VOCALS-REx will be compiled and made available to the atmospheric science community. In conjunction with other VOCALS-REx investigators, parameterizations of cloud microphysical processes in terms of cloud macrophysical characteristics will be developed. Second, expertise in the synergistic use of radar, lidar and in situ observations will be developed through graduate student training.