10 Applications of the Inverse Problem of Pollution Propagation
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radius (usually about 2–4 km) (Alenius et al. 2003) and enhanced buoyancy-driven
currents.
These features favour intricate spatio-temporal patterns in salinity and density,
and support a complicated interplay of the basin-scale cyclonic circulation, the exchange of water masses with the Baltic Proper, and the system of mesoscale (synoptic) eddies (Andrejev et al. 2004a, 2004b). In addition, these patterns become even
more complicated due to substantial seasonal variations in the wind field and the
incoming solar radiation, and to the possible presence of an ice cover (Myrberg and
Andrejev 2003; Andrejev et al. 2004a, 2004b; Myrberg et al. 2010b). Consequently,
the requirements for circulation modelling for the Gulf of Finland are as high as
for the SW Baltic Sea. The common circulation models with a grid step of 2–3 nm
(Myrberg et al. 2010b) apparently overlook a part of its dynamics, especially the
contribution by synoptic eddies to circulation and mixing.
10.4 Circulation and Trajectory Models
The quality of the circulation models is crucial for the success of the entire technology. Three different ocean models have been used to simulate the 3D dynamics of
the Baltic Sea and in the test areas for the applications of the technique developed
in 2009–2012 in the framework of the BONUS BalticWay cooperation.
10.4.1 The Rossby Centre Ocean Model RCO
A set of velocity fields was calculated by the Swedish Meteorological and Hydrological Institute using the Rossby Centre Ocean circulation model (RCO) for the entire
Baltic Sea (Chap. 4). The model details, set-up and extensive validation efforts are
described in a number of publications (Meier 2001, 2007; Meier et al. 2003, among
others). The bathymetric information is based on the data set of Seifert et al. (2001).
The RCO model is a further development of the Ocean Circulation and Climate Advanced Model (OCCAM) primitive-equation free-surface circulation model (based
on the Bryan–Cox–Semtner model, Webb et al. 1997) in z-coordinates. It covers the
entire Baltic Sea with a horizontal resolution of 2 nm and vertical resolution from
3 m in the uppermost layer down to 12 m in the deeper areas (for a total of 41 levels). This horizontal resolution is usually sufficient for eddy-resolving runs in the
Baltic Proper (Lehmann 1995) but is barely eddy-permitting in the Gulf of Finland
(cf. Albretsen and Røed 2010).
The model contains several parameterizations with a special importance for the
Baltic Sea, such as a two-equation turbulence closure scheme of the k–ε type to parameterize subgrid-scale mixing, open boundary conditions in the northern Kattegat
(in the sea area to the west of southern Sweden in Fig. 10.1), a sea-ice model and a
parameterization of the effect of breaking surface gravity waves. The time-splitting
329
radius (usually about 2–4 km) (Alenius et al. 2003) and enhanced buoyancy-driven
currents.
These features favour intricate spatio-temporal patterns in salinity and density,
and support a complicated interplay of the basin-scale cyclonic circulation, the exchange of water masses with the Baltic Proper, and the system of mesoscale (synoptic) eddies (Andrejev et al. 2004a, 2004b). In addition, these patterns become even
more complicated due to substantial seasonal variations in the wind field and the
incoming solar radiation, and to the possible presence of an ice cover (Myrberg and
Andrejev 2003; Andrejev et al. 2004a, 2004b; Myrberg et al. 2010b). Consequently,
the requirements for circulation modelling for the Gulf of Finland are as high as
for the SW Baltic Sea. The common circulation models with a grid step of 2–3 nm
(Myrberg et al. 2010b) apparently overlook a part of its dynamics, especially the
contribution by synoptic eddies to circulation and mixing.
10.4 Circulation and Trajectory Models
The quality of the circulation models is crucial for the success of the entire technology. Three different ocean models have been used to simulate the 3D dynamics of
the Baltic Sea and in the test areas for the applications of the technique developed
in 2009–2012 in the framework of the BONUS BalticWay cooperation.
10.4.1 The Rossby Centre Ocean Model RCO
A set of velocity fields was calculated by the Swedish Meteorological and Hydrological Institute using the Rossby Centre Ocean circulation model (RCO) for the entire
Baltic Sea (Chap. 4). The model details, set-up and extensive validation efforts are
described in a number of publications (Meier 2001, 2007; Meier et al. 2003, among
others). The bathymetric information is based on the data set of Seifert et al. (2001).
The RCO model is a further development of the Ocean Circulation and Climate Advanced Model (OCCAM) primitive-equation free-surface circulation model (based
on the Bryan–Cox–Semtner model, Webb et al. 1997) in z-coordinates. It covers the
entire Baltic Sea with a horizontal resolution of 2 nm and vertical resolution from
3 m in the uppermost layer down to 12 m in the deeper areas (for a total of 41 levels). This horizontal resolution is usually sufficient for eddy-resolving runs in the
Baltic Proper (Lehmann 1995) but is barely eddy-permitting in the Gulf of Finland
(cf. Albretsen and Røed 2010).
The model contains several parameterizations with a special importance for the
Baltic Sea, such as a two-equation turbulence closure scheme of the k–ε type to parameterize subgrid-scale mixing, open boundary conditions in the northern Kattegat
(in the sea area to the west of southern Sweden in Fig. 10.1), a sea-ice model and a
parameterization of the effect of breaking surface gravity waves. The time-splitting