Lagrangian Studies of Stratospheric Transport Barriers

9714384首席调查员Eluszkiewicz试图了解平流层中微量物种跨越对流层顶和热带与温带边界等内部障碍的物理过程。跨越这些边界的传输率对于确定包括平流层水蒸气以及较低平流层和对流层臭氧在内的主要组成气体的预算非常重要，并在评估超音速和亚音速飞机等向大气排放的微量气体的化学和气候影响方面发挥关键作用。尽管认识到这种输送的重要性，但由于有关的空间尺度往往小于航天器观测或使用欧拉平流方案计算得出的结果，在了解这种输送方面的进展受到了阻碍。在该项目下，PI将使用专门开发的拉格朗日轨迹包来模拟大尺度和小尺度输送的全球影响，该轨迹包并入地球物理流体动力学实验室SKYHI大气环流模式(GCM)。拉格朗日方法将用于探讨以下问题：(使用欧拉和拉格朗日方法计算的痕量气体分布的差异，以及这些差异对GCM计算的平流层空气平均年龄的影响(温带外平流层-对流层交换的性质和模式中模拟的穿过对流层顶的质量通量所揭示的季节模式)。从这项研究中获得的见解将有助于其他全球模式和/或同化模式的轨迹技术的一般发展。特别是，这项研究将研究在轨迹计算中使用的风数据对垂直坐标选择和采样频率的敏感性，包括在线执行计算的选项，即在风力发电模型的每个积分时间步长上进行计算。因此，这些研究将有助于更好地理解拉格朗日方法作为三维高分辨率平流方案和可视化工具的作用。

9714384 Eluszkiewicz The principal investigator seeks to understand the physical processes responsible for transport of trace species in the stratosphere across internal barriers such as the tropopause and the boundary between the tropics and extratropics. The transport rates across these boundaries are important in determining the budgets of key constituent gases, including stratospheric water vapor and lower stratospheric and tropospheric ozone, and play a crucial role in the assessment of the chemical and climatic impact of trace gases emitted to the atmosphere, for example by supersonic and subsonic aircraft. Despite its recognized importance, progress in understanding this transport has been impeded by the fact that the relevant spatial scales are often smaller than can be resolved by spacecraft observations or computed using Eulerian advection schemes. Under this project the PI will simulate the global effects of both large and small scale transport using a specially developed Lagrangian trajectory package incorporated into the Geophysical Fluid Dynamics Laboratory SKYHI general circulation model (GCM). The Lagrangian technique will be used to explore the following: ( The difference in the trace gas distributions computed using Eulerian and Lagrangian approaches and the impact of these differences on the mean age of stratospheric air as computed in a GCM ( The nature of stratosphere-troposphere exchange in the extratropics and the seasonal patterns as revealed by the mass fluxes across the tropopause simulated in the model. Insights gained from this research will be useful in the general development of trajectory techniques for other GCMs and/or assimilation models. In particular, this research will study the sensitivity to the choice of vertical coordinate and to the sampling frequency of the wind data used in the trajectory calculations, including the option of performing the calculations on-line, i.e., on each integration time step of the wind-generating model. These studies will thus contribute to a better understanding of the Lagrangian approach both as a three-dimensional high-resolution advection scheme and as a visualization tool.