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

海洋层积云普遍存在于凉爽的沿海上升流地区，被认为对地球气候系统具有相当重要的意义，是2008年POST（层积云顶部物理学）实验的重点。POST涉及海军研究生院CIRPAS双水獭飞机（2008年7月至8月在加利福尼亚中部海岸作业）的重点数据收集和支持数值模拟研究的结合。目前的工作将继续对POST原位机载测量进行分析，重点是根据多次飞行期间收集的数据计算夹带速度，并将采用层积云顶部附近“云洞”的有条件采样，并估计这些抑制区域的耗尽总水通量。夹带速度也将由沉降和层积云顶部生长的测量独立估计。先前发表的夹带“规则”将被重新审视，着眼于它们的批判性评估和潜在的改进，并关注剪切的作用和层积云顶部夹带界面层（EIL）内独特的物理特性。另一项独立但同时进行的工作将扩展一项基于模型的探索，探索2004-05年在加勒比海进行的RICO（海洋积云中的雨）项目观测到的信风积云中毛毛雨的形成。在这里，基于海盐的超巨型核（UGN）光谱在地面风速和海况的范围内以及伴随的云内液滴光谱将支持聚结和凝聚增长的计算，以估计这些积云基础之上的降水率。POST相关工作的智力价值集中在证明POST携带率测量精度的提高和云模式参数化的后续改进，而继续RICO建模工作将支持降水率对亚热带常见小积云中UGN浓度敏感性的定量表达（相对于更多二进制开关）的发展。通过与犹他大学的一名学生合作，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。

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.