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T. Soomere
neighbours on different coasts may serve as politically correct options. More comprehensive solutions can be found by globally minimizing the probability of pollution or by maximizing the time in question. All demonstrated solutions can be
applied for the optimization of (climatologically or seasonally valid) stationary locations as well as for the optimization of risks associated with moving sources
of danger. The presented approaches have used the nearshore as an example of
vulnerable areas and ship traffic as a source of danger. A generalization of the
technique to virtually any set of vulnerable areas and their values is straightforward.
The presence of semi-persistent current patterns as discussed in Chap. 9 is a
strong argument for the feasibility for this approach. The presented analysis provides a hint for a more general criterion based on the ability of certain introduced
measures to characterize the internal dynamics of surface currents. First of all, a
combination of the asymptotic values for the cumulative probability of coastal hits
and particle age (equivalently, the residence time of oil at sea in Chap. 11) with their
(spatial) standard deviation deserves attention as all these are virtually independent
of the ocean model resolution. Although these measures obviously depend on the
size of the water body, they implicitly characterize certain properties of currentdriven surface transport that cannot be extracted directly from classical Eulerian
velocity fields. The listed properties evidently differ considerably, for example, for
tide-dominated and microtidal basins of similar size. It is also natural to expect that
basins hosting mostly jet-like currents differ in this sense from regions with predominantly eddy-like dynamics. Most probably, relatively low-resolution (but at least
eddy-permitting) hydrodynamic models may be used for checking whether or not a
substantial decrease in environmental risks is possible from the discussed technique
in a particular region.
The importance of the model resolution becomes evident in attempts to construct
practical tools for decision-making. The presented material confirms that the derived
solutions can only be reliable if the model is eddy-resolving. The resulting optimum
locations for potentially dangerous activities depend, not surprisingly, substantially
on the specific target. The optimum solutions show also highly nontrivial dependence on the seasonal forcing patterns (in the Gulf of Finland, Chap. 11) or on the
overall flow regime in the transition zone between the Baltic Sea and the North
Sea (Chap. 10) It is now evident that simple heuristic solutions based on qualitative
arguments (e.g., a uniform shift of the entire fairway towards a less dangerous position) do not work. Instead, a largely meandering fairway may lead to a substantial
decrease in environmental risks.
An obvious measure of the overall potential of environmental benefit is the minimum value of the probability of a coastal hit, equivalently, the maximum particle
age. The areas hosting the extreme values are natural candidates for activities with
potentially large environmental consequences. It might be beneficial, for example,
to relocate to such an area a leaking vessel that cannot be brought into a harbour
because of rough weather or tough ice conditions. There might exist several minima
for the relevant distributions and thus also multiple options to minimize the consequences of accidents. A similar decision-making process can also be used when a
T. Soomere
neighbours on different coasts may serve as politically correct options. More comprehensive solutions can be found by globally minimizing the probability of pollution or by maximizing the time in question. All demonstrated solutions can be
applied for the optimization of (climatologically or seasonally valid) stationary locations as well as for the optimization of risks associated with moving sources
of danger. The presented approaches have used the nearshore as an example of
vulnerable areas and ship traffic as a source of danger. A generalization of the
technique to virtually any set of vulnerable areas and their values is straightforward.
The presence of semi-persistent current patterns as discussed in Chap. 9 is a
strong argument for the feasibility for this approach. The presented analysis provides a hint for a more general criterion based on the ability of certain introduced
measures to characterize the internal dynamics of surface currents. First of all, a
combination of the asymptotic values for the cumulative probability of coastal hits
and particle age (equivalently, the residence time of oil at sea in Chap. 11) with their
(spatial) standard deviation deserves attention as all these are virtually independent
of the ocean model resolution. Although these measures obviously depend on the
size of the water body, they implicitly characterize certain properties of currentdriven surface transport that cannot be extracted directly from classical Eulerian
velocity fields. The listed properties evidently differ considerably, for example, for
tide-dominated and microtidal basins of similar size. It is also natural to expect that
basins hosting mostly jet-like currents differ in this sense from regions with predominantly eddy-like dynamics. Most probably, relatively low-resolution (but at least
eddy-permitting) hydrodynamic models may be used for checking whether or not a
substantial decrease in environmental risks is possible from the discussed technique
in a particular region.
The importance of the model resolution becomes evident in attempts to construct
practical tools for decision-making. The presented material confirms that the derived
solutions can only be reliable if the model is eddy-resolving. The resulting optimum
locations for potentially dangerous activities depend, not surprisingly, substantially
on the specific target. The optimum solutions show also highly nontrivial dependence on the seasonal forcing patterns (in the Gulf of Finland, Chap. 11) or on the
overall flow regime in the transition zone between the Baltic Sea and the North
Sea (Chap. 10) It is now evident that simple heuristic solutions based on qualitative
arguments (e.g., a uniform shift of the entire fairway towards a less dangerous position) do not work. Instead, a largely meandering fairway may lead to a substantial
decrease in environmental risks.
An obvious measure of the overall potential of environmental benefit is the minimum value of the probability of a coastal hit, equivalently, the maximum particle
age. The areas hosting the extreme values are natural candidates for activities with
potentially large environmental consequences. It might be beneficial, for example,
to relocate to such an area a leaking vessel that cannot be brought into a harbour
because of rough weather or tough ice conditions. There might exist several minima
for the relevant distributions and thus also multiple options to minimize the consequences of accidents. A similar decision-making process can also be used when a