Collaborative Research: Physics of Stratocumulus Top (POST)

合作研究：层积云顶部物理学（POST）

• 批准号: 0736072
• 负责人: Qing Wang
• 金额: $ 5.01万
• 依托单位: Naval Postgraduate School
• 依托单位国家: 美国
• 项目类别: Interagency Agreement
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0736072&HistoricalAwards=false
• 关键词: Collaborative; Research; Physics; Stratocumulus; Top

Stratocumulus clouds (Sc) off the west coast of California will be studied using a combination of aircraft measurements and modeling. The objective is to improve the understanding of the physical processes that occur near Sc top, and that influence the cloud-top entrainment process and overall boundary-layer evolution. These processes include wind shear, entrainment rate, CTEI (cloud-top entrainment instability), solar and infrared radiation, hydrometeor and CCN (cloud condensation nuclei) effects, and the formation and role played by the EIL (entrainment interface layer). The study is a combination of field measurements and modeling. For the former, the CIRPAS Twin Otter research aircraft will be deployed out of Monterey for ~20 flights in Sc. It will carry a full complement of sensors to produce measurements related to these physical processes. Sensors include the UFT (ultra-fast temperature probe), PVM (fast particulate volume monitor), fast Lyman-Alpha hygrometer, PDI (phased Doppler interferometry probe), other droplet probes, gust probe, solar and infrared radiometers, and the standard set of Twin-Otter probes recording meteorology and aircraft operating properties. The aircraft will be deployed primarily in fields of unbroken Sc with an emphasis on porpoising maneuvers vertically above, through, and below the Sc top level to detect fine-scale changes in conditions. Boundary layer profiles and near-surface horizontal legs will be flown to deduce flux profiles through the sub-cloud boundary layer. NexSat and CloudSat products will be compared to aircraft measurements in real-time and used to help vector the aircraft to fields of Sc. The analysis phase of the field study includes comparisons between the measured physical processes and the calculated cloud-top entrainment velocities with the purpose of clarifying the influence of various processes on the entrainment velocities. The modeling phase of the study will cover a wide range of scales associated with these physical processes. The LEM (linear eddy model) looks at the finest scales associated with droplet size changes. New fine-scale LES (large-eddy simulation) will be applied with grid resolution comparable to the several-meters scale associated the expected typical entrained parcel size. A mesoscale model (COAMPS) will be used to study the larger-scale behavior of the Sc and the boundary layer, and also will be used in real-time to provide predictions for deploying the aircraft. Parameterizations of the cloud top entrainment velocity will be evaluated and improved. The intellectual merit of the project will be improved prediction of the behavior and evolution of Sc found over large areas of the sub-tropical oceans. This has proved to be difficult because of the imperfect understanding of the physical processes involved and the inability to measure them accurately. High on the priority list for better understanding is the entrainment process. The literature shows a lack of measurement success and predictive capability for this important process that affects Sc lifetime. This study uses a unique combination of aircraft measurements and modeling to focus on this deficiency. For the first time co-located high-rate microphysical, thermodynamic, and turbulence probes are used on a fixed-wing aircraft deployed for unraveling the physical interactions near Sc top. Broader impacts derive from this improved understanding of Sc behavior and evolution will be the ability to predict the behavior of low-level stratocumulus found over large ocean areas. This is needed given their major contribution to the planetary albedo that affects the planetary radiation balance and thus global warming.

将使用飞机测量和建模的组合研究加利福尼亚西海岸的层状云（SC）。目的是提高对SC TOP附近物理过程的理解，并影响云顶的夹带过程和整体边界层进化。这些过程包括风剪，夹带率，CTEI（云顶夹带不稳定性），太阳和红外辐射，水电和CCN（云凝结核）效应以及EIL（夹带界面层）所起的形成和作用。该研究是现场测量和建模的组合。对于前者来说，Cirpas Twin Otter Research飞机将在SC中以约20次飞行方式部署在蒙特雷。它将携带完整的传感器补充，以产生与这些物理过程有关的测量。传感器包括UFT（超快速温度探针），PVM（快速颗粒体积显示器），快速的Lyman-Alpha湿度计，PDI（PHASED POPPLER干涉探针），其他液滴探针，阵风探针，太阳能，太阳能和红外辐射仪以及双探测器记录的Twin-otter probers录制的twin-otter procs reaker twin-otter recordes reaker twin-otter reagres reagres reagres reagres reagries twin-otters录制的乘坐静物和乘坐乘坐的经营物业。该飞机将主要部署在不间断的SC领域，重点是在SC顶级上方，通过和下方垂直上方和下方进行操作，以检测条件的细微尺度变化。边界层轮廓和近地面水平腿将被飞行以通过子云边界层推断磁通剖面。 Nexsat和Cloudsat产品将与飞机实时测量进行比较，并用于帮助将飞机载入SC领域。现场研究的分析阶段包括测量的物理过程与计算出的云顶夹带速度之间的比较，目的是阐明各种过程对夹带速度的影响。该研究的建模阶段将涵盖与这些物理过程相关的广泛尺度。 LEM（线性涡流模型）着眼于与液滴尺寸变化相关的最佳尺度。新的细尺度LES（大涡模拟）将使用可与几米尺度相媲美的网格分辨率进行应用。中尺度模型（COAMP）将用于研究SC和边界层的较大规模行为，还将实时使用用于部署飞机的预测。将评估和改进云顶部夹带速度的参数化。该项目的智力优点将改善对亚热带海洋大区域的行为和演变的预测。事实证明，这很困难，因为对所涉及的物理过程以及无法准确衡量它们的物理过程的理解不深。优先列表中的高度理解是夹带过程。文献表明，对于影响SC寿命的这一重要过程中缺乏测量成功和预测能力。 这项研究使用了飞机测量和建模的独特组合，以关注这种缺陷。首次在部署的固定翼飞机上使用了共同定位的高速微物理，热力学和湍流探针，以揭示SC TOP附近的物理相互作用。从这种对SC行为和进化的改善的理解中产生的更广泛的影响将是预测在大海洋地区发现的低水平层流的行为。鉴于它们对影响行星辐射平衡并因此全球变暖的行星反照率做出了重大贡献。