1 Towards Mitigation of Environmental Risks
21
The entire technology thus combines a number of components into one entity.
Its corner stone is a high-resolution 3D circulation model that adequately resolves
the majority of mesoscale features in the sea area of interest. The model output provides the entire technology with (Eulerian) velocities at certain grid points and with
a certain temporal resolution. This data set makes it possible to evaluate Lagrangian
trajectories of single particles. For simplicity, we only consider the particular case
when these trajectories are locked to the uppermost layer and thus reflect the behaviour of the lighter fractions of oil pollution.
A proper statistical analysis of the trajectories leads to 2D maps of various quantities characterizing the damaging potential of different offshore sites in case of a
release of oil spill. Among those, the probability of hitting vulnerable areas and
the time it takes until the hit evidently have the largest value for decision-making.
The final step of the sequence of operations is decision-making. This is relatively
simple if a location of a single site is to be defined but may be highly nontrivial
when an optimal fairway must be constructed.
1.14 From Classical Physical Oceanography to Environmental
Management
The entire method essentially relies on the state-of-the-art knowledge of the physical
oceanography, meteorological factors driving the currents and processes on the sea
surface and the finest circulation model. A fundamental precondition of receiving a
certain benefit is the presence of (semi-)persistent patterns of currents or winds that
modify the otherwise homogeneous and isotropic statistics of surface-layer transport. As the nature of internal dynamics and the properties of such patterns vary
largely in different seas and oceans, it is natural to assume that the parameters of
the used models as well as the outcome of the entire technology are extremely sitespecific.
For the wide variety of seas surrounding Europe and suffering from extensive
anthropogenic impact (such as the Black Sea, Sea of Marmara, Adriatic Sea, North
Sea, Norwegian Sea, or Barents Sea), the situation is the most desperate in the Baltic
Sea. In the Baltic Sea (incl. the Kattegat) about 76 ports handle more than 1 million
tonnes of cargo per year. On the one hand, it is a relatively small brackish subbasin of the Atlantic Ocean with an extremely sensitive ecosystem (Leppäranta and
Myrberg 2009). This feature has been legally recognized by including this sea on
the list of particularly sensitive sea areas by the IMO (Lefebvre-Chalain 2007). On
the other hand, its extremely rich internal dynamics (incl. the absence of quasistationary current systems) makes it a perfect test area of the method for highlighting
the impact of usually concealed semi-persistent current patterns. On top of that,
the Baltic Sea is subject to enormous anthropogenic pressure. The number of ship
operations (voyages, excluding ferry traffic) in the Baltic Sea is estimated at 150,000
per year (Gollasch and Leppäkoski 2007), and it is assumed to increase considerably
in the future.
21
The entire technology thus combines a number of components into one entity.
Its corner stone is a high-resolution 3D circulation model that adequately resolves
the majority of mesoscale features in the sea area of interest. The model output provides the entire technology with (Eulerian) velocities at certain grid points and with
a certain temporal resolution. This data set makes it possible to evaluate Lagrangian
trajectories of single particles. For simplicity, we only consider the particular case
when these trajectories are locked to the uppermost layer and thus reflect the behaviour of the lighter fractions of oil pollution.
A proper statistical analysis of the trajectories leads to 2D maps of various quantities characterizing the damaging potential of different offshore sites in case of a
release of oil spill. Among those, the probability of hitting vulnerable areas and
the time it takes until the hit evidently have the largest value for decision-making.
The final step of the sequence of operations is decision-making. This is relatively
simple if a location of a single site is to be defined but may be highly nontrivial
when an optimal fairway must be constructed.
1.14 From Classical Physical Oceanography to Environmental
Management
The entire method essentially relies on the state-of-the-art knowledge of the physical
oceanography, meteorological factors driving the currents and processes on the sea
surface and the finest circulation model. A fundamental precondition of receiving a
certain benefit is the presence of (semi-)persistent patterns of currents or winds that
modify the otherwise homogeneous and isotropic statistics of surface-layer transport. As the nature of internal dynamics and the properties of such patterns vary
largely in different seas and oceans, it is natural to assume that the parameters of
the used models as well as the outcome of the entire technology are extremely sitespecific.
For the wide variety of seas surrounding Europe and suffering from extensive
anthropogenic impact (such as the Black Sea, Sea of Marmara, Adriatic Sea, North
Sea, Norwegian Sea, or Barents Sea), the situation is the most desperate in the Baltic
Sea. In the Baltic Sea (incl. the Kattegat) about 76 ports handle more than 1 million
tonnes of cargo per year. On the one hand, it is a relatively small brackish subbasin of the Atlantic Ocean with an extremely sensitive ecosystem (Leppäranta and
Myrberg 2009). This feature has been legally recognized by including this sea on
the list of particularly sensitive sea areas by the IMO (Lefebvre-Chalain 2007). On
the other hand, its extremely rich internal dynamics (incl. the absence of quasistationary current systems) makes it a perfect test area of the method for highlighting
the impact of usually concealed semi-persistent current patterns. On top of that,
the Baltic Sea is subject to enormous anthropogenic pressure. The number of ship
operations (voyages, excluding ferry traffic) in the Baltic Sea is estimated at 150,000
per year (Gollasch and Leppäkoski 2007), and it is assumed to increase considerably
in the future.