The structure of the tropopause and the transport and mixing of mass and chemical species between the stratosphere and troposphere both affect the role of the stratosphere in climate. Dynamical aspects of stratosphere-troposphere exchange. The tropopause is shown by the thick line.
Thin lines are isentropic or constant potential temperature surfaces labelled in Kelvins.
The broad arrows show transport by the global-scale circulation which is driven by the extratropical pump. NATO Advanced Research Workshop on stratosphere-troposphere exchange, Cambridge, 1993.