A one-dimensional photochemical model of the troposphere with a trade-wind boundary-layer parameterization

Refinement of the vertical transport parameterization in a one-dimensional photochemical model of the troposphere by incorporating results from a model of boundary layer dynamics representative of a remote tropical environment is presented. The photochemical model is then used to compute tropospheric profiles of selected trace constituents to advance our understanding of how vertical transport processes affect the distributions and budgets of trace gases in the troposphere.

The boundary layer model used in this study simulated the multi-layer structure that characterizes the divergent trade-wind regions of the earth. The vertical transport parameterization includes the stuctural and mass-flow characteristics of a layer of shallow, dispersed cumulus. Vertical mass fluxes of trace constituents were calculated with reference to the better-known flux of water vapor. Model-derived vertical profiles of key trace constituents are compared with profiles from the photochemical model with conventional flux parameterizations and to the available measured data for the remote marine troposphere. The experiment simulates the observed vertical structure of tropospheric ozone in marine tradewind environments reasonably well. In addition, this study indicates that the abundance of reactive nitrogen species found in remote tropical regions of the world cannot be supported by the estimated magnitude of local sources, implying that long-range transport from higher latitudes may account for a sizeable input of reactive nitrogen to remote tropical regimes.