Physics Of Stratocumulus Top (POST) and Rain in Cumulus over the Ocean (RICO) Data Analysis

层积云顶部物理 (POST) 和海洋积云降雨 (RICO) 数据分析

• 批准号: 1020445
• 负责人: Hermann Gerber
• 金额: $ 7.47万
• 依托单位: Gerber Scientific Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1020445&HistoricalAwards=false
• 关键词: Physics; Stratocumulus; Top; POST; Rain

Marine stratocumulus, which are ubiquitous over regions of cool coastal upwelling and thought to be of considerable importance to Earth's climate system, were the focus the 2008 POST (Physics Of Stratocumulus Top) experiment. POST involved a combination of focused data collection by the Naval Postgraduate School's CIRPAS Twin Otter aircraft (operating off the coast of central California during July-August 2008) and supporting numerical modeling studies. The current effort will pursue analysis of POST in situ airborne measurements with a focus on calculating the entrainment velocity from data collected during multiple flights, and will employ the conditional sampling of "cloud holes" near stratocumulus top and the estimation of depleted total water flux in these suppressed regions. Entrainment velocities will also be independently estimated from measurements of subsidence and the growth of stratocumulus top. Previously published entrainment "rules" will be revisited with an eye toward their critical evaluation and potential improvement with attention to the role of shear and the unique physics within the entrainment interface layer (EIL) atop stratocumulus clouds. A separate but contemporaneous effort will expand a model-based exploration of drizzle formation in trade-wind cumuli observed during the 2004-05 RICO (Rain in Cumulus over the Ocean) project conducted over the Caribbean Sea. Here, sea-salt based ultra-giant nuclei (UGN) spectra over a range of surface wind speeds and sea states and accompanying in-cloud droplet spectra will support calculations of coalescence and condensational growth to estimate precipitation rates well above the bases of these cumulus clouds.The intellectual merit of the POST-related effort centers on the challenge of demonstrating improved accuracy of POST entrainment rate measurements and follow-on improvements in cloud model parameterizations, while continued RICO modeling efforts will support development of a quantitative expression (vs. more binary switch) for the sensitivity of precipitation rates to concentrations of UGN in small cumulus common to the subtropics.Broader impacts of the proposed work relate to improved understanding of the role of clouds in climate change scenarios, and through collaborations with a student at the University of Utah.

海洋层积云，普遍存在于凉爽的沿海上升流地区，被认为对地球的气候系统相当重要，是2008年POST（层积云顶部物理学）实验的重点。 POST包括由海军研究生院的CIRPAS Twin Otter飞机（2008年7月至8月在加州中部海岸附近运行）收集的集中数据和支持数值模拟研究的组合。 目前的努力将追求分析的POST现场空中测量，重点是计算卷吸速度从多个航班期间收集的数据，并将采用有条件的采样“云洞”附近的层积云顶部和估计耗尽的总水通量在这些抑制区域。 卷吸速度也将根据沉降和层积云顶部生长的测量结果独立估计。 以前发表的夹带“规则”将重新审视他们的关键评价和潜在的改进，注意剪切的作用和独特的物理夹带界面层（EIL）顶部层积云。 一个单独的，但同时的努力将扩大在2004-05年RICO（海洋上的积云雨）项目在加勒比海进行的贸易风积云毛毛雨形成的模式为基础的探索。 在这里，在一定范围的地面风速和海况下的海盐基超巨核（UGN）光谱以及伴随的云内液滴光谱将支持聚结和凝结增长的计算，以估计这些积云底部以上的降水率。与POST相关的工作的智力价值集中在证明POST夹带率测量的改进精度的挑战上，并遵循以下原则：云模型参数化的改进，而继续RICO建模工作将支持定量表达的发展（相对于更多的二元开关）降水率对亚热带常见的小积云中UGN浓度的敏感性。拟议工作的更广泛影响涉及提高对云在气候变化情景中的作用的理解，并通过与犹他州大学的一名学生合作。