Lagrangian Studies of Stratospheric Transport Barriers

点击翻译按钮获取中文摘要

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.