Various Eulerian air quality models are used to understand complex reaction pathways for species transformation and to assess air quality regulations. Those air quality models use in general K-theory concepts to describe the subgrid-scale vertical mixing in the atmospheric boundary layer (ABL). K-theory presents turbulent mixing processes as local and confines turbulent mixing to adjacent layers. More recently, various studies confirmed that during events of increased convection this assumption does not represent appropriate turbulent mixing of chemically active species in the ABL.
This study describes how events of increased turbulent mixing are assessed by two Eulerian photochemical grid models (UAM-V, CAMx). Both models were tested in detailed studies for different regions mainly in the eastern U.S. However, these previous studies did not evaluate, in particular, model simulation during events of increased vertical mixing and their effect on ozone simulation for the surface layer. For this study both models were applied on the OTAG data base D2 of July 10-17, 1995, for periodes of strong vertical mixing. Modeled vertical ozone profiles are compared to measured data obtained during the SOS campaign for the area of Nashville, Tennessee. Finally, this paper recommends vertical mixing schemes which presents turbulent mixing of chemically active species more appropiate
Symposium on Interdisciplinary Issues in Atmospheric Chemistry