Stratospheric Chemistry Models

The JHU atmospheric sciences group is involved with several different activities using multi-dimensional coupled chemical - physical models to understand past changes and predict future changes in stratospheric composition and global climate.

NASA GSFC Coupled Chemistry Climate Model
We are collaborating with scientists at NASA Goddard Space Flight Center (GSFC) on a ``Chemistry-Climate Studies Using General Circulation Models" project. This project involves the development and assessment of an integrated chemistry-climate model (CCM), and the use of this CCM to investigate the interactions between atmospheric composition and climate dynamics. The specific scientific goals of this proposal are to quantify the impact of dynamics on stratospheric ozone recovery, the role of stratospheric and tropospheric ozone in climate change, and the overall influence of atmospheric chemistry and aerosols on climate change. For more detail see NASA GSFC web page .

Early versions of the GSFC models have been used to examine several different issues relevant to the above project. For example, a multi-decadal simulations was used to examine the role of extratropical wave driving in Interannual variability of stratospheric trace gases .

CCM Validation Activity (CCMVal)
The CCM Validation Activity for SPARC (CCMVal) is an international project aimed at process-oriented validation of coupled chemistry-climate models (CCMs).

The initial stages of this project have involved the identification of the key chemical, dynamical, transport, and radiative processes in the troposphere-stratosphere system, and development of observationally-based diagnostics of these processes. These diagnostics are being applied to a large number of CCMs from around the world to assess how well these processes are simulated. The majority of these CCMs are performing simulations of the past and future evolution of stratospheric ozone that are being used in the WMO/UNEP 2006 Ozone Assessment.

For more information see the CCMVal web site .

Stratospheric Age of Air
Correctly simulating the transport within the atmosphere is a critical for accurate simulations of ozone and other trace gases. An important aspect of the transport are the distributions of transit times ("age spectra"). A major research focus in recent years has been to quantify these transport times from measurements of trace gases and to use these observations to assess the transport models. More details are here.