Chemistry-Climate Model Simulations of Twenty-First Century Stratospheric Climate and Circulation Changes
Abstract
The response of stratospheric climate and circulation to increasing amounts of greenhouse gases (GHGs) and ozone recovery in the twenty-first century is analyzed in simulations of 11 chemistry climate models using near-identical forcings and experimental setup. In addition to an overall global cooling of the stratosphere in the simulations (0.59 +/- 6 0.07 K decade(exp -1) at 10 hPa), ozone recovery causes a warming of the Southern Hemisphere polar lower stratosphere in summer with enhanced cooling above. The rate of warming correlates with the rate of ozone recovery projected by the models and, on average, changes from 0.8 to 0.48 Kdecade(exp -1) at 100 hPa as the rate of recovery declines from the first to the second half of the century. In the winter northern polar lower stratosphere the increased radiative cooling from the growing abundance of GHGs is, in most models, balanced by adiabatic warming from stronger polar downwelling. In the Antarctic lower stratosphere the models simulate an increase in low temperature extremes required for polar stratospheric cloud (PSC) formation, but the positive trend is decreasing over the twenty-first century in all models. In the Arctic, none of the models simulates a statistically significant increase in Arctic PSCs throughout the twenty-first century. The subtropical jets accelerate in response to climate change and the ozone recovery produces awestward acceleration of the lower-stratospheric wind over the Antarcticuring summer, though this response is sensitive to the rate of recovery projected by the models. There is a strengthening of the Brewer Dobson circulation throughout the depth of the stratosphere, which reduces the mean age of air nearly everywhere at a rate of about 0.05 yr decade(exp -1) in those models with this diagnostic.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 15, 2010
- Accession Number
- ADA558889
Entities
People
- C. Bruehl
- D. W. Waugh
- E. Cordero
- H. Akiyoshi
- I. Cionni
- Joanna M. Austin
- M. P. Chipperfield
- Neal Butchart
- T. G. Shepherd
- V. Eyring
Organizations
- Johns Hopkins University