Abstract
Winds and convective mixing from a general circulation model of the atmosphere have been applied in a chemical tracer model (CTM) to simulate the global distribution and temporal variability of chlorofluorocarbons (CFCs). The seasonal cycle in moist convection, with maximum activity over continents in summer, leads to an annual cycle in the surface concentration of CFCs. Emissions are retained in the lowest levels of the atmosphere during winter, and surface concentrations peak near sources. In this season, CFCs from European sources are carried by low‐level winds into the Arctic. During summer, vertical exchange is more efficient, and pollutants are transported more rapidly to the middle atmosphere. Consequently, concentrations of CFCs during summer are relatively low near the surface and elevated in the middle troposphere. Time series analysis of data from Adrigole, Ireland, indicates that the model accurately simulates long‐range transport of air pollution. The model reproduces global distributions and trends for CFC‐11 and CFC‐12 observed by the ALE experiment; however, subgrid diffusion must be introduced into the model in order to reproduce the observed interhemispheric gradient. Interhemispheric exchange occurs mainly in the upper tropical troposphere, producing a profile which increases with altitude in the southern hemisphere, in agreement with observations. The distribution of CFCs is such that it is necessary to apply important corrections to observations at surface stations in order to derive global distributions.
Highlights
Models based on numerical solution of the equations describingconservationof mass,momentum, and energy have contributed in an essential fashion to our evolving understandingof atmosphericcirculationsincethe early studiesby Charney et al [1950] and Phillips [1956-]
The recent study by Golombekand Prinn [1986] was the first to examine the AtmosphericLifetime Experiment (ALE) data set with a three-dimensional model, focusing on stratosphericdistributionsand globallifetimesof CFCs; their model has insufficient vertical and horizontal resolution in the troposphere to simulate in detail the observedtroposphericconcentrations
The distributionsof in providing a globally self-consistentset of winds, conver- CFC-11 and CFC-12 were initialized in model year 1976
Summary
Models based on numerical solution of the equations describingconservationof mass,momentum, and energy have contributed in an essential fashion to our evolving understandingof atmosphericcirculationsincethe early studiesby Charney et al [1950] and Phillips [1956-]. Space Studies to calculate structure and wind fields for the the general circulation These CFC simulations provide a atmosphere and to describe the vertical exchange of air by quantitative evaluation of the impact of subgrid, mesoscale convection [Hansen et al, 1983]. The model was formulated mixing on global tracer transport and place upper limits on its initially for efficient simulation of climate. Elsewhere,it is shown that this empirical apallow ready investigationof the effectof spatial resolutionand proach gives good agreement for the latitudinal distrito study schemesfor parameterization of processesoperating butionof SSKr[Jacobet al., thisissue].We are continuingto on small scales involving the boundary layer and cumulus assessthe importance of subgriddiffusion for other chemical convection.In the presentseriesof studiesthe GCM is usedto tracers and for the circulation itself, through direct inclusion provide a set of wind fields and other variables which are in the GCM.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
