Abstract
Abstract. Ozone depletion is caused by the anthropogenic increase of halogen-containing species in the atmosphere, which results in the enhancement of the concentration of reactive chlorine and bromine in the stratosphere. To reduce the influence of anthropogenic ozone-depleting substances (ODS), the Montreal Protocol was agreed by Governments in 1987, with several Amendments and Adjustments adopted later. In order to assess the benefits of the Montreal Protocol and its Amendments and Adjustments (MPA) on ozone and UV radiation, two different runs of the chemistry-climate model (CCM) SOCOL have been carried out. The first run was driven by the emission of ozone depleting substances (ODS) prescribed according to the restrictions of the MPA. For the second run we allow the ODS to grow by 3% annually. We find that the MPA would have saved up to 80% of the global annual total ozone by the end of the 21st century. Our calculations also show substantial changes of the stratospheric circulation pattern as well as in surface temperature and precipitations that could occur in the world without MPA implementations. To illustrate the changes in UV radiation at the surface and to emphasise certain features, which can only be seen for some particular regions if the influence of the cloud cover changes is accounted for, we calculate geographical distribution of the erythemally weighted irradiance (Eery). For the no Montreal Protocol simulation Eery increases by factor of 4 to 16 between the 1970s and 2100. For the scenario including the Montreal Protocol it is found that UV radiation starts to decrease in 2000, with continuous decline of 5% to 10% at middle latitudes in the both Northern and Southern Hemispheres.
Highlights
(ODS), the Montreal Protocol was agreed by Governments led to the promulgation of the Montreal Protocol
The ozone decrease in the troposphere is slightly smaller than it obtained by Morgenstern el al. (2008) due to additional tropospheric ozone production by the increased level of UV radiation, which was not included in their model
We evaluate the usefulness of international agreements such as the Montreal Protocol on the basis of numerical experiments carried out with the modern chemistryclimate model SOCOL in the framework of the Chemistry-Climate Model Validation Activity (CCMVal) campaign
Summary
CCM SOCOL is a three-dimensional global chemistryclimate model. It was developed at the PhysicalMeteorological Observatory (Davos, Switzerland) in collaboration with ETH (Zurich, Switzerland) and Voeikov Main Geophysical Observatory The CTM MEZON calculates the distributions of concentrations of 45 trace gases from the major atmospheric groups, which are determined by 118 gas phase reactions, 33 photolytic reactions, and 16 heterogeneous reactions. The model parts of the CCM SOCOL (MEZON and MAECHAM4) exchange data on the fields of major dynamical variables and radiatively active gases every 2 h. A number of model deficiencies in describing the global transport of chemical species and heterogeneous processes in the Polar region have been found (Eyring et al, 2007). The new model version more correctly describes the distribution, transport and transformation of the atmospheric halogen-containing species and ozone in the middle and high latitudes in the stratosphere of both hemispheres (Schraner et al, 2008). The improved model version (SOCOL 2.0), with eleven other modern CCMs, has been tested in the analysis of the simulation of Southern Hemisphere ozone evolution in the last 25 yr of the 20th century (Karpechko et al, 2010)
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