Monday, 10 January 2000: 5:14 PM
During the last decade, a number of large-scale numerical regional models
with varying degree of complexity have been developed for the transport
and transformation of mercury in the atmosphere. However mercury unlike
other heavy metals has been identified to have a long residence time of
the order of one year, which makes it a global pollutant. This is due to
the fact that the most significant form of mercury in the atmosphere,
namely elemental mercury exists in gaseous form, it is chemically least
reactive, has low solubility in water and takes part in volatilization
process at the earth surface. Therefore, although very useful in
analyzing episodic situations, the regional scale models developed thus
far are limited in their capability in providing insights into mercury
budgets, long term trends, trans-boundary exchanges and polar mercury
pollution because they have to depend on prescribed background
concentrations and lateral boundary fluxes of mercury. For the reasons
mentioned above, global atmospheric mercury model is a more appropriate
tool to address the question of mercury cycle in the atmosphere. The
primary purpose of this paper is to describe development of a global
mercury model with a variable-resolution grid structure which could be
used to construct a regional high-resolution window for a desired region
on the global domain.
The mercury transport model being developed is an Eulerian model embedded in the Canadian meteorological centre's 'global environmental multiscale model', which is the operational weather forecasting model. This has an advantage of availability of advanced parameterizations of physical processes such as cloud related processes in the model for the modeling of physio-chemical processes of mercury.
The model will be integrated in a data assimilation mode where the meteorological data is reinitialized to observed fields once a day. Multi-year simulations of mercury transport in the atmosphere will be performed. Description of the model and preliminary evaluation of results will be presented at the conference.
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