Summertime Transport Pathways and Dynamics from Northern India and Tibetan Plateau to the Lower Stratosphere: Insights from Idealized Tracer Experiments

It is important to study the transport dynamics from the surface to the stratosphere since it plays a critical role in determining the concentration and distribution of chemical species in the stratosphere in addition to emission and chemistry. We use the idealized tracer experiments and investigate the sensitivity of the transport and its associated timescale to the surface emission region during Northern Hemisphere summer. We find that tracers emitted from the surface region of northern India and Tibetan Plateau travel to the Northern Hemisphere lower stratosphere in an overall shorter timescale, compared to tracers that are emitted from the surrounding regions. Analysis of the tracer budget reveals that the tracer is transported to the tropical lower stratosphere rapidly in the first 5 days due to vertical eddy transport and afterward in a month or two advection associated with the Brewer-Dobson circulation. Meanwhile the tracer is also transported to the northern extratropical lower stratosphere in the first 3 months due to horizontal eddy mixing. The results highlight the uniqueness of the northern India region in the summertime transport to the lower stratosphere and implications for the transport of short-lived chemical species in the destruction of stratospheric ozone.