Validation of the integrated RAMS-Hg modelling system using wet deposition observations for eastern North America

Using the well-known Regional Atmospheric Modelling System (RAMS) version 4.3 an integrated system able to simulate the atmospheric mercury cycle has been developed. Basic processes of the mercury atmospheric cycle have been incorporated into the atmospheric model. The model deals with elemental Hg (Hg⁰), divalent gaseous Hg (Hg²) and particulate Hg (Hg^P). Wet deposition mechanisms used to describe the removal of Hg² and Hg^P are merged with the detailed cloud microphysical scheme in order to provide better representation of the wet deposition processes. The advantages of this approach have been examined through results intercomparison with simulated Hg wet deposition using CMAQ-Hg from previous work for two evaluation periods: 4 April–2 May 1995, and 20 June–18 July 1995. An attempt to clarify the main parameters that affect wet deposition mechanism of mercury is also made.