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

东南太平洋被世界上最大的亚热带层积云覆盖，很少有人观测到。气候模型对这些云的模拟很差，这对全球气候敏感性以及对大气颗粒物如何影响气候的模拟产生了影响。虽然模型模拟正在改进，但由于对云、气溶胶和毛毛雨相互作用的理解存在差距，因此对云和粒子的更好的模型处理受到限制。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）来解决这些差距。（VAMOS是一个国际科学项目，美国季风系统的变化）。这项研究是VOCALS雷克斯的核心项目，将于2008年10月至11月在东南太平洋进行。将从飞机、船只和陆地上进行密集观测。这些数据将被用来解决组织成两个主题的假设：气溶胶-云-降水之间的相互作用，在海洋边界层和上层海洋，陆地和大气之间的化学和物理耦合，这个项目的重点是从NSF C-130飞机收集的数据，以测试有关的假设气溶胶，云和降水之间的相互作用在东南太平洋的层积云。来自C-130和其他平台的数据将被综合，以了解决定从低云落下的降水量的过程，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、云结构和光学特性的机制，C-130飞机的取样策略涉及两种不同类型的飞行：横截面飞行任务将涉及从智利北方海岸沿沿着20度南纬飞行横截面，穿过粒子浓度和云特性的强烈梯度，到达西经85度左右的层积云覆盖的气候最大值。这些飞行任务将建立一幅海洋边界层云和降水特性的平均值和变化率以及该层内外气溶胶物理和化学特性的图像。POC-Drift任务将研究开放单元（POCs）口袋中发生的微物理和动力学状态和过程，并将其与周围的阴天层积云进行对比。飞行将与其他参与飞机和NOAA研究船罗纳德H布朗协调。POC-漂移飞行模式进行多次飞行（可能是多架飞机）研究，跟踪单个POC，以观察比单次飞行更长的时间内的气溶胶和云的演变。将进行大涡模拟（LES），以建立观测分析。气溶胶-云-毛毛雨相互作用将被纳入LES框架使用一个简化的气溶胶源-汇收支方程，这将被用来，连同C-130的观测，以测试假设的气溶胶，云和降水之间的反馈超过SEP。更广泛的影响，这个项目是在形成两个博士论文的基础。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。作为VOCALS-REx的一部分生成的观测数据集将在GEWEX（全球能量和水循环实验）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，项目执行员将为双语教育推广方案“通向宇宙的窗口”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.