Hemispheric Differences in the Transport of Chemical Tracers in the Tropical Lower Stratosphere

The distributions of ozone, water vapor and other chemical tracers in the tropical lower stratosphere are strongly influenced by transport processes such as vertical advection (upwelling) and quasi-horizontal mixing. Previous studies quantified the relative role of these processes based on tropics-wide average characteristics under common assumption of well mixed tropics. Very recently, multiple instruments provided us with evidence that show significant differences in trace gas distributions and transport between the northern and southern tropics (NT and ST respectively). Thus, latitudinal variations within the tropics have to be considered in order to understand the balance between upwelling and quasi-horizontal mixing in the tropical lower stratosphere. In this study we investigate the differences in transport of chemical tracers in the Southern (0-20S) and Northern (0-20N) tropical lower stratosphere using historical runs from Goddard Earth Observing System Chemistry Climate Model (GEOSCCM-v5 ). Tracer budgets in the model are analyzed based on the Transformed Eulerian Mean (TEM) framework. This approach allows to quantify the relative importance of transport processes on tracer concentration. We also examine zonal and interannual variations (QBO variations) in the NT and ST ozone cycles and determine the role of upwelling and quasi-horizontal mixing in the tropical lower stratosphere.