EXAMINATION OF TRACER TRANSPORT IN THE NCAR CCM2 BY COMPARISON OF CFCL(3) SIMULATIONS WITH ALE GAGE OBSERVATIONS/

The latest version of the National Center for Atmospheric Research com munity climate model (CCM2) contains a semi-Lagrangian tracer transpor t scheme for the purpose of advecting water vapor and for including ch emistry in the climate model. One way to diagnose the CCM2 transport i s to simulate CFCl3 in the CCM2 since it has a well-known industry-bas ed source distribution and a photochemical sink and to compare the mod el results to Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment observations around the globe. In this paper we focus on t his comparison and discuss the synoptic scale issues of tracer transpo rt where appropriate. We compare the model and observations on both 12 -hour and monthly timescales. The higher-frequency events allow us to diagnose the synoptic scale transport in the CCM2 associated with the observational sites and to determine uncertainties in our high-resolut ion source distribution. We find that the CCM2 does simulate many of t he key features such as pollution events and some seasonal transports, but there are still some dynamical features of tracer transport such as the storm track dynamics and cross-equatorial flow that merit furth er study in both the model and the real atmosphere.