Collaborative Research: Cloud System Evolution in the Trades

本研究的目的是了解边界层云，气溶胶和热力结构的演变沿着轨迹内的北太平洋信风使用的观测从NSF/NCAR湾流V（HIAPER）。这项工作包括表征云，降水和气溶胶领域的层积云（Sc）和晴天积云（Cu）制度内的副热带东风在北方太平洋和使用大涡模拟（LES）模式来模拟云的演变沿着轨迹采样。智力优点：这些表征沿着轨迹将被设计来帮助我们理解和模拟两个对流制度之间的过渡-气候系统中的一个关键因素。LES模式已经成为一个强大的工具，拉格朗日模拟的副热带云量转换，但很少有好的数据集，全面测试这些模拟。特别是，缺乏足够的观测耦合演变的气溶胶，云滴数浓度和降水在这种转变。因此，观测战略将是从北太平洋上空的过渡区逆风处对气溶胶、云、降水和边界层特性进行采样，并在两天和四天后对这些地区进行重新采样。这种拉格朗日方法的目的是最大限度地减少不确定性的大尺度强迫由于在对流层低层的水平平流的空气质量从较冷到温暖的海面温度，从而促进模型模拟和隔离关键的物理过程。观测系统的两个关键要素将是新开发的HIAPER云雷达和HIAPER高光谱分辨率激光雷达。HCR将用于提供云和降水特征。HSRL将提供云边界和气溶胶特性时，查看非多云量。飞机上的全套探测器将用于现场测量气溶胶、云、降水和湍流特性。加州西海岸和夏威夷之间的航班将采用两种操作模式。其中一项将包括从Sc到Cu过渡区上游和下游边界层上方的飞行高度对云和边界层进行遥感（制图）。另一个将涉及过渡区上游和下游两个或三个选定地区的云下和云层的详细剖面，以便对气溶胶、云、降水和湍流进行详细的现场测量。在测量腿上，将使用下投式探空仪获得边界层内和边界层上方的热力学和风结构。计划在2015年6月至7月的时间范围内进行几次飞行序列。在这些飞行中进行的观察将用于评估水分，干静态能量和质量预算，通过估计这些参数之间的变化，上游Sc区域采样的一个飞行和下游Cu区域采样的后续飞行。观测结果的综合将为LES研究提供一个观测框架，从而更好地了解行业中的云系统演变。更广泛的影响：该项目将开发观测和分析技术及战略，以促进今后旨在研究其他观测平台不易到达的偏远地区边界层云的飞行任务的发展。所开发的数据集将有助于评价卫星检索技术，并有助于评价应用于微物理、中尺度、区域和全球等各种尺度的模型和模型参数化。该项目的教育部分将包括对研究生和本科生进行数据收集过程、飞行操作和随后分析数据以解决关键科学问题的技术方面的培训。此外，还将开发将该项目的观察结果纳入可在本科生和研究生一级使用的教学和学习模块的方法。

This study aims to understand the evolution of the boundary layer cloud, aerosol and thermodynamic structures along trajectories within the north-Pacific trade-winds using observations from the NSF/NCAR Gulfstream V (HIAPER). This effort includes characterization of the cloud, precipitation and aerosol fields in the stratocumulus (Sc) and the fair-weather cumulus (Cu) regimes within the subtropical easterlies over the northern Pacific and the use of Large Eddy Simulation (LES) models to simulate the cloud evolution along the trajectories sampled. Intellectual merit: These characterizations along trajectories will be designed to aid in our understanding and simulation of the transition between the two convective regimes - a critical factor in the climate system. LES models have become a robust tool for Lagrangian simulations of subtropical cloudiness transitions, but there are few good datasets for comprehensively testing these simulations. In particular, adequate observations of the coupled evolution of aerosol, cloud droplet number concentration and precipitation during such transitions are lacked. Thus, the observing strategy will be to sample aerosol, cloud, precipitation, and boundary layer properties upwind from the transition zone over the North Pacific and to resample these areas two and four days later. This Lagrangian approach is designed to minimize uncertainties in the large-scale forcing due to horizontal advection in the lower troposphere as air masses move from colder to warmer sea surface temperatures and thus facilitate model simulations and isolate critical physical processes. Two key elements of the observing system will be a newly developed HIAPER Cloud Radar (HCR) and the HIAPER High Spectral Resolution Lidar (HSRL). The HCR will be used to provide cloud and precipitation characteristics. The HSRL will provide cloud boundaries and aerosol characteristics when viewing non-cloudy volumes. A full suite of probes on the aircraft will be used for in situ measurements of aerosol, cloud, precipitation, and turbulence properties. Two modes of operations will be made on flights between the west coast of California and Hawaii. One will include remote sensing (mapping) of the clouds and boundary layer from flight levels above the boundary layer made upstream and downstream from the Sc to Cu transition zone. The other will involve detailed profiling in the subcloud and cloud layer in two or three selected areas upstream and downstream from the transition zone to make detailed in situ measurements of aerosols, clouds, precipitation, and turbulence. On the surveying legs dropsondes will be used to obtain the thermodynamic and wind structure in and above the boundary layer. Several flight sequences are planned for the June-July 2015 timeframe. The observations made on these flights will be used to evaluate the moisture, dry static energy and mass budgets by estimating the changes in these parameters between the upstream Sc region sampled on one flight and the downstream Cu region sampled on the subsequent flights. The synthesis of the observations will provide an observational framework for LES studies that will provide a better understating of cloud system evolution in the trades. Broader impacts: The project will develop observing and analysis techniques and strategies that will facilitate the development of future missions aimed at studying boundary layer clouds in remote areas that are not easily reached by other observing platforms. The data sets developed will be useful for evaluating satellite retrieval techniques and for evaluating models and model parameterizations applied to a wide range of scales--microphysical, mesoscale, regional, and global. The educational components of this project will include the training of graduate and undergraduate students on the technical aspects of the data collection processes, flight operations, and the subsequent analysis of data to address key science questions. Further, integration of observations from the project into teaching and learning modules that can be used at both the undergraduate and the graduate level will be developed.