Collaborative Research: Cloud System Evolution in the Trades

这项研究的目的是利用NSF/NCAR湾流V(HIAPER)的观测资料，了解北太平洋信风中边界层云、气溶胶和热力结构的演变。这项工作包括描述层积云(SC)和北太平洋副热带东风内的晴天积云(Cu)制度中的云、降水和气溶胶的场，并使用大涡模拟(LES)模式来模拟云沿采样轨迹的演变。智力优势：这些轨迹特征将有助于我们理解和模拟两个对流系统之间的过渡--这是气候系统中的一个关键因素。LES模式已经成为拉格朗日模拟副热带云量转换的有力工具，但很少有好的数据集来全面检验这些模拟。特别是，对这种过渡期间气溶胶、云滴数密度和降水的耦合演变缺乏足够的观测。因此，观测战略将是从北太平洋过渡区的上风向采样气溶胶、云、降水和边界层特性，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由于对流层低层水平平流引起的大范围强迫的不确定性，因为气团从较冷的海洋表面温度移动到较暖的海洋表面温度，从而促进模式模拟并隔离关键的物理过程。观测系统的两个关键部件将是新开发的HIAPER云雷达(HCR)和HIAPER高光谱分辨率激光雷达(HSRL)。HCR将用于提供云和降水特征。当观测非云量时，HSRL将提供云的边界和气溶胶特征。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。在加利福尼亚州西海岸和夏威夷之间的航班上将有两种运营模式。其中一项将包括从SC到铜过渡区上游和下游的边界层上方的飞行高度对云和边界层进行遥感(测绘)。另一项是在过渡带上游和下游选定的两到三个地区的云下和云层中进行详细的廓线，以对气溶胶、云、降水和湍流进行详细的现场测量。在测量支路上，将使用滴落探测仪获得边界层及其上方的热力结构和风结构。计划在2015年6月至7月期间进行几次飞行。在这些航班上进行的观测将被用于评估湿度、干静态能量和质量收支，方法是估计在一次飞行中采样的上游SC区和在后续飞行中采样的下游Cu区之间的这些参数的变化。观测结果的综合将为LES研究提供一个观测框架，这将更好地淡化云系在交易中的演变。更广泛的影响：该项目将制定观测和分析技术和战略，以促进未来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估卫星检索技术以及评估适用于各种尺度--微物理、中尺度、区域和全球尺度--的模型和模型参数。该项目的教育部分将包括对研究生和本科生进行关于数据收集过程的技术方面的培训、飞行操作以及随后的数据分析，以解决关键的科学问题。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与学模块。

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.