Turbulent transport of trace gases from the planetary boundary layer (PBL) to the free troposphere is believed to be an important process limiting reactions of short-lived chemical species in the free troposphere. Using the GISS/Harvard/UCI Chemistry Transport Model (CTM), several well-known local and non-local "closure" methods for parameterizing turbulent transport in global models are studied for their effects on trace gas simulations. Meteorological data from the CTM are used to initialize temperature, moisture, and wind profiles within a nested one-dimensional grid in the model PBL, and trace gas profiles are determined from the CTM's second-order moments advection scheme. Application of the selected closure method provides turbulent fluxes and a resultant trace gas profile which is passed back to the CTM using the second-order moments. The use of different closure methods leads to significant differences in free-tropospheric concentrations of inert and short-lived reactive chemical species, demonstrating the necessity of including an accurate simulation of PBL turbulence in studies of tropospheric chemistry
Symposium on Interdisciplinary Issues in Atmospheric Chemistry