Collaborative Research: Data Assimilation Analysis of the Boundary Layer and Convection Initiation During International H2O Project (IHOP)

国际H2O项目（IHOP_2002）的野外阶段提供了广泛的中尺度气象观测，以帮助提高对大气边界层（ABL）、对流起爆（CI）和定量降水预报（QPF）的尺度和影响过程的认识。以往的研究主要集中在目标移动场观测数据的收集和分析、对流前边界层结构和演化分析、积云形成和对流抑制/起生过程等方面。本研究的目的是通过首次将先进的数据同化工具应用于额外的IHOP案例，为边界层环流动力学以及导致积云形成和CI的相关过程提供新的认识。智力优势：主要研究人员将继续分析三维雷达导出的边界层气流，并从移动中网、测深、飞机和其他目标移动和固定IHOP平台进行风和热力学参数的现场测量。边界层气流与绝对湿度和虚拟温度的现场测量相结合，提供了记录边界层中调节可降水量和迫使二次环流和云或风暴发展的动力和输送过程的唯一手段。因此，对IHOP观测的新分析对于继续评估有关水汽供应和气流演变对不同中尺度环境中边界形成和CI影响的所有假设至关重要。详细的IHOP观测将以几种不同的方式进行分析。将产生主观分析和可视化，将所有可用的数据纳入CI的相关尺度。观测密度将利用在先前拨款下开发的拉格朗日分析来提高，该分析基于多多普勒风合成，沿拉格朗日轨迹分布几乎守恒的变量。最后，将评估使用集合卡尔曼滤波方法将这些增强观测直接同化到云/中尺度模式的潜力，以确定控制局域边界层和对流层低层环流发展的动力强迫过程，这些过程促进或阻止CI。因此，该研究将大大增加和补充其他正在进行的关于风暴和中尺度对流系统的数据同化研究，并为影响风暴形成和演变以及风暴数值预报的所有尺度的中尺度数据同化提供更无缝的端到端方法。更广泛的影响：这项工作将推动对前所未有的数据集的持续分析。拟议的工作涉及研究生——从而有助于培养下一代研究人员——同时促进合作机构之间的研究伙伴关系。结合以往和正在进行的分析，将对低层边界附近非均质对流边界层中发生的过程有新的认识，并将这些过程与雷暴的形成联系起来。所获得的知识将有助于在数据同化和定量降水预报方面取得新的进展，包括数值上的和主观上的进展，提高预报对流是否、何时、何地发展的能力。

The field phase of the International H2O Project (IHOP_2002) provided a wide range of mesoscale meteorological observations to help improve understanding of the scales of, and processes influencing, the atmospheric boundary layer (ABL), convection initiation (CI) and quantitative precipitation forecasting (QPF). Previous research focused on the collection and analysis of targeted mobile field observations, the analysis of the preconvective boundary layer structure and evolution, and the cumulus formation and convection inhibition/initiation processes. The goal of this research is to provide new understanding of the dynamics of boundary layer circulations and the related processes leading to cumulus formation and CI by applying advanced data assimilation tools for the first time to additional IHOP cases. Intellectual Merit: The Principal Investigators will continue analysis of 3-D radar-derived boundary layer airflow and in-situ measurements of winds and thermodynamic parameters from mobile mesonets, soundings, aircraft, and other targeted mobile and fixed IHOP platforms. The combination of boundary layer airflow with in-situ measurements of absolute humidity and virtual temperature provide the only means of documenting the dynamical and transportive processes acting in the boundary layer to regulate precipitable water and force the development of secondary circulations and clouds or storms. Thus, new analyses of IHOP observations are essential to continue evaluating all hypotheses concerning the impact of water vapor supply and airflow evolution on boundary formation and CI in different mesoscale environments. Detailed IHOP observations will be analyzed in several different ways. Subjective analyses and visualizations will be produced incorporating all available data on the relevant scales for CI. Observation density will be enhanced utilizing a Lagrangian analysis developed under the previous grant that distributes nearly conserved variables along Lagrangian trajectories based on multiple-Doppler wind syntheses. Finally, the potential of assimilating these enhanced observations directly into a cloud/mesoscale model using the Ensemble Kalman Filter method will be assessed to determine the dynamical forcing processes controlling the development of localized boundary layer and lower tropospheric circulations that either promote or prevent CI. Thus, the research will substantially augment and complement other ongoing data assimilation studies of storms and mesoscale convective systems and contribute to a more seamless, end-to-end methodology for mesoscale data assimilation at all scales affecting storm formation and evolution and numerical forecasting of storms. Broader Impacts: This effort will advance the ongoing analysis of an unprecedented data set at previously unobserved scales. The proposed work involves graduate students - thus contributing to the training of the next generation of researchers - while promoting research partnerships between the collaborating institutions. Through the combination of the previous and ongoing analyses, new understanding will emerge regarding the processes occurring in the heterogeneous convective boundary layer near low-level boundaries and relate those processes to the formation of thunderstorms. The knowledge gained will be useful for developing new advances, both numerical and subjective, in data assimilation and quantitative precipitation forecasting by improving the ability to forecast if, when, and where convection will develop.