Dynamics and Impacts of Mesoscale Gravity Waves in the Moist Baroclinic Jet-Front Systems

本研究探讨重力波的基本动力学及其与湿对流和斜压波的相互作用。它将通过利用理想湿斜压波的高分辨率模拟以及分析实际案例建模和过去野外活动中的飞机观测，来表征湿斜压射流锋面系统中产生的中尺度重力波的来源、动力学和影响。本研究的主要目标如下。(1)研究理想湿斜压波高分辨率模拟中重力波的特征、来源、传播和动力学，研究不同湿对流强度模拟中重力波起爆和传播的异同，了解重力波与小尺度湿对流和大尺度背景斜压波的耦合和相互作用；并评估这些重力波的动量/能量通量及其对大尺度环流的影响。(2)探讨重力波和平衡调节在小尺度对流向大尺度斜压波高阶误差能量传递中的作用，以及在理想实验和实际数据事件下对湿斜压射流锋系统中尺度可预测性的影响。(3)通过分析2008年“平流层-对流层区域运输分析试验”（START08）的高分辨率飞机观测数据和数值模拟，表征了温带对流层上层-平流层下层区域中尺度重力波的来源、传播、动力学和影响，并定量比较了飞机和卫星观测估算的动量和能量通量与模式模拟计算的动量和能量通量。知识价值：引力波在大气中无处不在，在各种大气过程中发挥着重要作用，这些过程对对流层天气、平流层动力学、臭氧化学和大气环流具有重要影响。它们可以传递大量的能量和动量，发起和组织对流，并产生大气湍流。重力波的动量输送和沉积对大气环流有重要的影响。要更好地了解这些过程，就需要完全了解重力波产生的机制，以及它们的特征、分布和变化。本项目的最终目标是在以往NSF支持下重力波干动力学研究取得的进展和成功的基础上，了解对流层斜压射流锋系统产生的中尺度重力波的动力学和影响及其与湿对流的相互作用。更广泛的影响：更好地了解中尺度重力波及其与潮湿过程的相互作用，可能有助于更好地了解动力学，改进对流触发和调节以及相关恶劣天气的预报。更好地理解气流不平衡和中尺度重力波可以为中尺度资料同化和中尺度预报提供指导。对重力波过程的更好理解也有助于更好地参数化非地形和非对流中尺度重力波在对流层和平流层之间的能量和动量输送。该项目将资助和培养两名研究生。它还将促进大学与几家领先研究机构之间的研究合作。

This research explores the fundamental dynamics of gravity waves and their interaction with moist convection and baroclinic waves. It will characterize the source, dynamics and impacts of the mesoscale gravity waves generated in the moist baroclinic jet-front systems through utilizing high-resolution simulations of idealized moist baroclinic waves along with analyzing real-case modeling and aircraft observations during past field campaigns. The major objectives of the research are following. (1) Investigate the characteristics, source, propagation and dynamics of gravity waves simulated in high-resolution simulations of idealized moist baroclinic waves, examine the similarities and differences of wave initiation and propagation between simulations with varying intensity of moist convection, understand the coupling and interactions of gravity waves with small-scale moist convection and large-scale background baroclinic waves, and assess the momentum/energy fluxes from these gravity waves and their impacts on the large-scale circulation. (2) Explore the role of gravity waves and balance adjustment in the upscale error energy transfer from small-scale convection to largescale baroclinic waves and the impacts on mesoscale predictability of moist baroclinic jet-front systems under both idealized experiments and real-data events. (3) Characterize the source, propagation, dynamics and impacts of mesoscale gravity waves in the extratropical uppertropospheric lower-stratospheric region through analyzing high-resolution aircraft measurements and numerical simulations during the 2008 Stratosphere-Troposphere Analyses of Regional Transport Experiment (START08), and quantitatively compare the momentum and energy fluxes estimated from aircraft and satellite observations with those calculated from model simulations.Intellectual Merit: Gravity waves are ubiquitous in the atmosphere and play a fundamental role in a wide variety of atmospheric processes that have important implications for tropospheric weather, stratospheric dynamics, ozone chemistry and the general circulation. They can transfer significant amounts of energy and momentum, initiate and organize convection, and produce atmospheric turbulence. The momentum transport and deposition by gravity waves have significant impacts on the general circulation of the atmosphere. A better knowledge of these processes demands a complete understanding of the mechanisms by which the gravity waves are generated, together with their characteristics, distribution and variability. Building on the progress and success on dry dynamics of gravity waves achieved under previous NSF supports, the ultimate goal of this project is to understand the dynamics and impacts of the mesoscale gravity waves generated by the tropospheric baroclinic jet-front systems and their interactions with moist convection.Broader Impacts: Better understanding of mesoscale gravity waves and their interaction with moist processes may lead to better understanding of the dynamics and improved forecasts of convective triggers and modulation as well as the associated severe weather. Better understanding of flow imbalance and mesoscale gravity waves may provide guidance on mesoscale data assimilation and mesoscale predictability. Better understanding of gravity wave processes may also lead to better parameterization of the energy and momentum transport between the troposphere and stratosphere by non-topographic and non-convective mesoscale gravity waves. This project will fund and train two graduate students. It will also foster research collaborations between the university and several leading research institutions.