Collaborative Research: Measurement and Analysis of the Preconvective Boundary Layer and Convection Initiation during International H2O Project (IHOP)

俄克拉荷马大学和宾夕法尼亚州立大学的这个合作项目是国际H2O项目(IHOP)的一部分。IHOP是一个大型的多机构、多研究人员的项目，重点是测量水蒸气和水蒸气的可变性。该项目的目标是增进对对流启动的了解，提高短期降水预报技能，并测试各种仪器测量水汽四维特征的能力。IHOP的现场阶段将于2002年春夏进行，将为研究提供广泛的中尺度气象观测，以更好地了解水汽可变性的尺度和影响过程。这项假设驱动的研究的目的是增进对导致深层潮湿积云对流开始的过程的理解。虽然一些研究已经研究了边界层结构的某些方面，但对引起对流启动的原因知之甚少。IHOP将提供开始评估和修订关于对流启动过程和边界层水蒸气作用的假设所需的综合数据集。首席调查员将获取和分析雷达获取的三维边界层气流，以及从流动设施现场测量的风和热力学参数。边界层气流与绝对湿度和虚拟温度的现场测量相结合，提供了记录作用于边界层的动力和输送过程的唯一手段，以调节可降水量并推动二次环流的发展。因此，这些观测对于评估有关水蒸气供应和气流演变对边界形成和对流启动的影响的假设至关重要。详细的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，纳入有关对流启动尺度的所有可用数据。利用一种先进的时空转换方案，通过基于多多普勒风合成沿拉格朗日轨迹分布几乎保守的变量，将提高观测密度。最后，这些增强的观测将被同化为中尺度模式，以确定控制局地边界层环流发展的动力强迫过程，这些局地边界层环流促进或阻止对流启动。这一努力将导致在以前没有观测到的尺度上收集和分析史无前例的数据集。通过这项工作，将对低层边界附近发生的过程以及这些过程如何调节雷暴的形成有一个全新的理解。这些知识将有助于通过提高预测对流是否、何时和在哪里发展的能力，在定量降水预报中发展新的数字和主观方面的进展。

This collaborative project between the University of Oklahoma and the Pennsylvania State University is part of the International H2O Project (IHOP). The IHOP is a large multi-agency, multi-investigator project that focuses on the measurement of water vapor and water vapor variability. The goal of this project is to improve understanding of convective initiation, increase short-term precipitation forecast skills and test the capabilities of various instruments to measure the four dimensional characteristics of water vapor. The field phase of the IHOP will be conducted during the Spring and Summer of 2002 and will provide a wide range of mesoscale meteorological observations for studies to gain a better understanding of the scales of, and processes influencing, water vapor variability.The goal of this hypothesis-driven research is to improve understanding of the processes leading to the initiation of deep, moist cumulus convection. Though several studies have examined certain aspects of boundary layer structure little is known about what causes convective initiation. IHOP will provide the comprehensive data sets needed to begin evaluating and revising hypotheses concerning convection initiation processes and the role of boundary layer water vapor. The Principal Investigators will acquire and analyze three dimensional radar-derived boundary layer airflow and in-situ measurements of winds and thermodynamic parameters from mobile facilities. The combination of boundary layer airflow with in-situ measurements of absolute humidity and virtual temperature provides the only means of documenting the dynamical and transport processes acting in the boundary layer to regulate precipitable water and force the development of secondary circulations. Thus these observations are essential for evaluating hypotheses concerning the impact of water vapor supply and airflow evolution on boundary formation and convection initiation.Detailed observations will be analyzed in several different ways. Subjective analyses and visualizations will be produced incorporating all available data on relevant scales for convection initiation. Observation density will be enhanced utilizing an advanced time-to-space conversion scheme by distributing nearly conservative variables along Lagrangian trajectories based on multi-Doppler wind syntheses. Finally, these enhanced observations will be assimilated into mesoscale models to determine the dynamical forcing processes controlling the development of localized boundary layer circulations that either promote or prevent convection initiation.This effort will result in the collection and analysis of an unprecedented data set at scales previously not observed. Through this work, a completely new understanding will emerge regarding the processes occurring near low-level boundaries and how these processes regulate the formation of thunderstorms. The knowledge will be useful for developing new advances, both numerical and subjective, in quantitative precipitation forecasting by improving the ability to forecast if, when, and where convection will develop.