STRATOSPHERIC TRACE CONSTITUENTS SIMULATED BY A 3-DIMENSIONAL GENERAL-CIRCULATION MODEL - COMPARISON WITH UARS DATA

Constituent distributions are presented from the NASA Langley three-dimensional general circulation model, incorporating a comprehensive chemistry scheme. A 7-year, gas phase model simulation was performed to investigate long-term model stability, In addition, a 1-year simulation was made using parameterized polar heterogeneous processes and reactions occurring on sulfate aerosols. The results of these simulations are compared with species climatologies and with satellite data sets in order to characterize and evaluate model performance and identify aspects of the chemical scheme requiring improvement. The agreement between the modeled seasonal variation of total ozone and the measurement climatologies is satisfactory but with some differences with respect to the depth and persistence of the southern springtime ozone depletion. Comparisons of the model simulation with observations made from UARS were performed. There is good accord between the microwave limb sounder observations of ozone and the model. Areas of agreement and disagreement are revealed between the model and the cryogenic array etalon spectrometer measurements of HNO3 and ClONO2, suggesting the need for a more detailed representation of sulfate aerosol processes in the model. The comparison between the modeled and the measured partitioning of odd chlorine species is improved in the upper stratosphere by the inclusion of an additional pathway to HCl from the reaction of ClO + OH.