Information-Modeling Technology for the Environmental Monitoring - New Ecoinformatics Tools in Environmental Science: Applications and Decision-making - page 102

1.7.6 Global Sulfur Cycle Modeling

Modeling of global sulfur cycle is particularly needed in connection with acid rains.
There are numerous models that are parameterized global sulfur cycle taking into
consideration of different hypotheses and assumptions concerning the chemistry and
transport components. One of the known global models for the sulfur cycle is
STOCHEM-Ed model (Collins et al. 1998). It is 3-D Lagrangian chemistry-transport
model. Stevenson et al. (2003) studied modified STOCHEM-Ed model taking into
consideration of the volcanic component. It was shown that:

volcanic emissions constitute 10 % of the global SO 2 source to the atmosphere,
but from 26 % of the SO 2 burden, and 14 % of the sulfate aerosol burden; and

￿

volcanic SO 2 dominates large regions of the free troposphere, particularly in the
tropics.

￿

The version of the sulfur unit proposed here, in contrast to the known hydro-
dynamic models of the long-distance transport, takes into account the fluxes of

sulfur compounds between the hydrosphere, atmosphere, soil, and biota. The model
does not consider the vertical strati

fl

cation of the atmosphere. The characteristics of

sulfur fluxes averaged vertically are calculated for both the land and ocean (Fasham

2003; Zaikov et al. 1991; Zlatev et al. 1992). The spatial digitization of the bio-
sphere and the World Ocean corresponds to the criterion inherent to the global
model. The elements of the block-scheme of the model of the biogeochemical cycle
of sulfur are described in Tables 1.16 and 1.17 . This scheme is realized in every cell
ʩ ij of the Earth

fl

ʩ ijk of the World Ocean.
Interaction between the cells and compartments is organized through the climate
unit of the global model. Therefore the equations of the sulfur unit lack the terms
re

' s surface and in every compartment

ecting the dynamic patter of the spatial transformation of the sulfur reservoirs.
With notations assumed in Tables 1.16 and 1.17 taken into account, the equations
describing the balance relationships between the reservoirs of sulfur compounds
will be written in the form:

fl

dAH2SL
dt

¼ C 1 þ C 2 þ C 3 C 4 þ C 21 ;

dASO2L
dt

¼ C 4 þ C 5 þ C 6 C 7 C 8 C 9 ;

dASO4L
dt

¼ C 9 þ C 3 þ C 20 C 11 C 12 ;

dS
dt ¼ C 17 C 16 C 19 ;

dSO4L
dt ¼ C 10 þ C 11 þ C 12 þ C 16 C 3 C 13 C 14 ;