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

很少被观测到的东南太平洋被世界上最大的亚热带层积云覆盖。气候模型对这些云的模拟很差，对全球气候敏感性和对大气颗粒物如何影响气候的模拟都有影响。虽然模式模拟正在改进，但对云和粒子的更好的模式处理受到对云、气溶胶和毛毛雨相互作用理解上的差距的限制。该项目是模拟和观测综合的结合，将使用Voals-Rex(瓦莫斯海洋-云-大气-陆地研究区域实验)来解决这些差距。(VAMOS是一个国际科学项目，美洲季风系统的可变性)。这项研究是人声雷克斯的核心项目，将于2008年10月至11月在东南太平洋上空进行。将从飞机、船只和陆地现场进行密集观测。这些数据将被用来处理两个主题的假设：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。该项目的重点是从NSF C-130飞机收集的数据，以检验与东南太平洋平流层积云中气溶胶、云和降水之间的相互作用的假设。来自C-130和其他平台的数据将被综合起来，以了解决定从低云落下的降雨量的过程，包括气溶胶的影响，以及毛毛雨影响近地表大气的动力学和热力学、云的结构和光学特性以及气溶胶微物理的机制。C-130飞机的抽样战略涉及两种不同类型的飞行：横断面飞行任务将涉及沿南纬20度的横断面从智利北部海岸向外飞行，跨越颗粒浓度和云性质的强烈梯度，直至西经约85度的层积云的气候最大值。这些飞行任务将建立海洋边界层中云和降水特性以及该层及其上方的气溶胶物理和化学特性的平均和变率的图景。POC-漂移任务将研究开放单体(POC)口袋中发生的微物理和动力学状态和过程，并将它们与周围阴沉的层积云进行对比。飞行将与其他参与飞机和NOAA科考船罗纳德·H·布朗协调。POC-漂移飞行模式在单个POC之后进行多次飞行(也可能是多架飞机)研究，以观测比单次飞行更长时间的气溶胶和云的演变。将在观测分析的基础上进行大涡模拟(LES)。气溶胶-云-毛毛雨相互作用将被纳入LES框架中，使用一个简化的气溶胶源-汇预算方程，这将与C-130观测一起被用来检验关于SEP上气溶胶、云和降水之间的反馈的假设。该项目的广泛影响构成了两篇博士论文的基础。该项目是声乐区域实验的核心组成部分，国际声乐协会是该实验的首席科学家。作为VOALS-REX的一部分产生的观测数据集将在全球能源和水循环实验(Gewex)云系统研究边界层云工作组进行的模型相互比较中发挥重要作用。此外，PIS还将为双语教育外展项目“宇宙之窗”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.