Assessing and understanding the impact of stratospheric dynamics and variability on the earth system

The Modelling the Dynamics and Variability of the Stratosphere-Troposphere System (DynVar) activity of the World Climate Research Programme's (WCRP) Stratospheric Processes and their Role in Climate (SPARC) project is a multidisciplinary research forum focused on the impact of stratospheric dynamics and variability. The stratosphere plays an important role in determining the climate response to volcanic and solar forcing. An early numerical study by Boville and Baumhefner (1990) explored the impact of the stratosphere on tropospheric predictability, finding that tropospheric error growth rates increased when the stratosphere of their model was degraded. In a complementary study, Jung and Barkmeijer (2006) find that forcing perturbations applied only in the stratosphere can impact the troposphere in just a few days, demonstrating the potential for model error in the stratosphere to corrupt a surface forecast. A number of NWP centers now include a better representation of the stratosphere to improve short-range forecasts. 119