Overview on the Chemistry-Climate Model Validation Activity for SPARC (CCMVal)

Kurzfassung

A new Chemistry-Climate Model Validation Activity for SPARC (CCMVal) has been established, based on experiences within the GCM-Reality Intercomparison Project for SPARC (GRIPS) and on the concept that was developed in a SPARC workshop on process-oriented CCM validation, held in Grainau, Germany in November 2003. As more climate models include chemical components, the time has arrived for formal comparisons of these coupled chemistry-climate models (CCMs). Within SPARC, this new activity will be one of the supporting “pillars” of the integrated themes. The goal of the new activity is to improve understanding of CCMs and their underlying GCMs (General Circulation Models) through process-oriented validation. One outcome of this effort is expected to be improvements in how well CCMs represent physical, chemical, and dynamical processes. In addition, this effort will focus on understanding the ability of CCMs to reproduce past trends and variability and providing predictions from ensembles of long model runs. Achieving these goals will involve comparing CCM constituent distributions with (robust) relationships between constituent variables as found in observations. At the Grainau workshop, a table of key diagnostics was defined in the four areas of radiation, dynamics, transport, and stratospheric chemistry and microphysics. The plan is that with the table defined, modelers will decide (based on their own priorities and resources) which diagnostics to examine in any particular application. In this way, the CCM community can provide the maximum amount of useful scientific information for upcoming WMO/UNEP and IPCC assessments.