VOCALS: C-130 Observations and Numerical Modeling of Marine Boundary Layer Clouds during the VOCALS Regional Experiment (REx)

很少观测到的东南太平洋被世界上最大的亚热带层积云覆盖。气候模式无法很好地模拟这些云，从而对全球气候敏感性和它们对大气粒子如何影响气候的模拟产生影响。虽然模式模拟正在改进，但由于对云、气溶胶和毛毛雨之间相互作用的理解不足，对云和粒子的更好模式处理受到了限制。该项目是建模和观测综合的结合，将使用VOCALS-REx （VAMOS海洋-云-大气-陆地研究区域实验）来解决这些空白。（VAMOS是一个国际科学项目，即美国季风系统的变异性）。这项研究是VOCALS REx的核心项目，该项目将于2008年10月至11月在东南太平洋进行。将从飞机、船只和陆地站点进行密集观测。这些数据将用于解决以下两个主题的假设：海洋边界层中的气溶胶-云-降水相互作用以及上层海洋、陆地和大气之间的化学和物理耦合。这个项目的重点是从美国国家科学基金会C-130飞机收集的数据，以测试东南太平洋上的层积云中气溶胶、云和降水之间相互作用的假设。来自C-130和其他平台的数据将被综合，以了解决定低云降水数量的过程，包括气溶胶的影响，以及毛毛雨影响近地面大气动力学和热力学、云结构和光学性质以及气溶胶微物理的机制。C-130飞机的抽样策略包括两种不同类型的飞行：横断面任务将包括沿南纬20度的智利北部海岸飞行横断面，跨越颗粒浓度和云性质的强烈梯度，到达西经85度左右层积云覆盖的气候最大值。这些任务将建立海洋边界层云和降水特性的平均和变化的图像，以及该层内和以上的气溶胶物理和化学特性。POC-Drift任务将研究开放细胞口袋（POCs）中的微物理和动态状态及其过程，并将其与周围的阴天层积云进行对比。飞行将与其他参与的飞机以及美国国家海洋和大气管理局的罗纳德·H·布朗号研究船协调。POC-Drift飞行模式对单个poc进行多飞行（可能是多飞机）研究，以观察比单次飞行更长的时间内气溶胶和云的演变。大涡模拟（LES）将在观测分析的基础上进行。气溶胶-云-细雨的相互作用将被纳入LES框架，使用简化的气溶胶源-汇预算方程，并将与C-130观测一起使用，以测试关于气溶胶，云和降水之间反馈的假设。该项目的更广泛影响将形成两篇博士论文的基础。该项目是VOCALS区域实验的核心组成部分，PI是该实验的首席科学家。VOCALS-REx生成的观测数据集将在GEWEX（全球能源和水循环实验）云系统研究边界层云工作组进行的模式比对中发挥重要作用。此外，pi还将为双语教育推广项目“通往宇宙之窗”（Windows to the Universe）制作材料。

The sparsely observed Southeast Pacific Ocean is covered by the world's largest subtropical sheet of stratocumulus clouds. Climate models poorly simulate these clouds with consequences for the global climate sensitivity and for their simulations of how atmospheric particles affect the climate. While model simulations are improving, better model treatments of clouds and particles are limited by gaps in the understanding of the interactions of clouds, aerosols, and drizzle. This project is a combination of modeling and observational syntheses that will use VOCALS-REx (the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment) to address these gaps. (VAMOS is an international science project, the Variability of the American Monsoon System).This study is a core project in VOCALS REx, which will take place over the Southeast Pacific Ocean during Oct-Nov 2008. Intensive observations will be made from aircraft, ships, and land sites. These data will be used to address hypotheses organized into two themes: aerosol-cloud-precipitation interactions in the marine boundary layer and chemical and physical couplings between the upper ocean, the land, and the atmosphere.The focus of this project is on data collected from the NSF C-130 aircraft to test hypotheses related to the interactions between aerosols, clouds and precipitation in stratocumulus clouds over the Southeast Pacific. Data from the C-130 and other platforms will be synthesized to understand the processes that determine the quantity of precipitation falling from low clouds, including the impact of aerosols, and mechanisms by which drizzle influences the dynamics and thermodynamics of the near-surface atmosphere, cloud structural and optical properties, and aerosol microphysics.The sampling strategy for the C-130 aircraft involves two distinct types of flights:. Cross-Section missions will involve flying cross-sections along 20 degrees South from the Northern Chilean coast out, across strong gradients in particle concentrations and cloud properties, to the climatological maximum in stratocumulus cloud cover at approximately 85 degrees West. These missions will build up a picture of the mean and variability in cloud and precipitation properties in the marine boundary layer, and aerosol physical and chemical properties both in and above that layer.. POC-Drift missions will study the microphysical and dynamical state and processes occurring in pockets of open cells (POCs) and contrast them with surrounding overcast stratocumulus. Flights will be coordinated with other participating aircraft and with the NOAA research vessel Ronald H Brown. The POC-Drift flight pattern conduct multi-flight (and possibly multi-aircraft) studies following individual POCs to observe aerosol and cloud evolution over a period longer than a single flight.Large eddy simulations (LES) will be conducted to build upon the observational analysis. Aerosol-cloud-drizzle interactions will be incorporated into in the LES framework using a simplified aerosol source-sink budget equation, and this will be used, together with the C-130 observations, to test hypotheses concerning the feedbacks between aerosols, clouds and precipitation over the SEP.Broader impacts of this project are in forming the foundation of two doctoral theses. This project is a central component of the VOCALS Regional Experiment, for which the PI is the lead scientist. The observational datasets generated as part of the VOCALS-REx will play an important role in model intercomparisons carried out by the GEWEX (Global Energy and Water Cycle Experiment) Cloud System Study boundary-layer cloud working group. In addition, the PIs will produce materials for Windows to the Universe, a bilingual educational outreach program.