Stratospheric variability and trends in IPCC model simulations

Output from a series of general circulation model experiments for the The Intergovemental Panel on Climate Change (IPCC) Fourth Assessment Report are analyzed to evaluate the sensitivity of the stratosphere to CO2 forcing using both 20th and 21st century model output. Model simulations of the 20th century are compared with observed temperatures and winds to better understand model variability and the role of the top boundary location on stratospheric simulations. The analysis then focuses on examining the evolution and variability of the polar vortex for different scenarios of the 21st century. The influence of stratospheric change on the troposphere will also be discussed.