The stratosphere is increasingly recognized as an important component of the climate system. Observational and modeling studies show that stratospheric conditions may be able to influence both weather and climate. Under previous National Science Foundation support, the researcher has worked on several fronts to elucidate the influences of the stratosphere on the tropospheric circulation. In this project, the research will further investigate the stratospheric impacts on weather and climate by focusing on idealized modeling studies.
These studies are intended to complement work done with state-of-the art climate models. Idealized climate models differ from comprehensive climate models in that the physical parameterizations have been highly simplified; this permits explorations of parameter space sensitivities and establishes the numerical robustness of the computed results. These idealized models will be used to study the impact of stratospheric ozone and greenhouse gases on the circulation of the coupled stratosphere-troposphere system, including their effects on the Brewer-Dobson circulation, and to investigate the dynamics and predictability of stratospheric sudden warmings and their impacts on the tropospheric circulation and weather forecasts.
The broader impacts of this project include contributions to the important task of attributing climate change, specifically, the stratospheric role, the possible improvement of extended-range weather forecasts from using knowledge of stratospheric conditions, contributions to the development and improvement of comprehensive climate models, links to international research efforts, and the training of postdoctoral scientists and graduate and undergraduate students.
This award was used to study several aspects of the atmospheric circulation and climate. Specifically, these questions were carefully explored, and each resulted in several peer-reviewed publications in the scientific literature. 1. Do the winds in the stratosphere affect surface weather, and would our forecasts be improved if stratospheric conditions where incorporated into current forecast models? The answer is yes, and was obtained with a simplified modeling exercise that allows for great clarity. It was also confirmed with more complex models, that represent the atmosphere and the climate system in all its complexity. 2. Has the formation of the ozone hole affected surface climate? The answer is a most definite yes. In fact, our work suggest that, for the Southern Hemisphere in the summertime, the formation of the ozone hole has been more important than increasing greenhouse gases in producing a clear trend in the position of the jet and the width of the subtropical dry zones. 3. Will the implementation of the Montreal Protocol, which will lead to a closing of the ozone hole in the next 50 years, have an impact on surface climate? Again, the answer is a clear yes. The vast majority of climate models show that, in the the next several decades, the closing of the ozone hole will oppose the effects of increasing greenhouse gases and, in fact, produce a substantial mitigation of climate change in the Southern Hemisphere.
