6 The Gulf of Finland
185
Fig. 6.1 Scheme of the Gulf of Finland. Graphics by M. Viška
6.2 General Features of the Gulf of Finland Affecting
the Circulation Dynamics: The Forcing
6.2.1 Topography
The elongated, narrow and relatively shallow Gulf of Finland is the easternmost
basin in the Baltic Sea, surrounded by Finland, Russia and Estonia (Fig. 6.1). The
gulf lies between 59°11 N, 22°50 E and 60°46 N, 30°20 E (Alenius et al. 1998;
Leppäranta and Myrberg 2009). Even in the Baltic Sea scales, it is a relatively small
basin. Its length is about 400 km and the width varies from 48 km between Tallinn
and Porkkala to 135 km between Narva Bay and Kotka. Its volume and surface
area (1,103 km 3 and 29,948 km 2 , respectively) are about 5 % of the volume and
about 7.5 % of the surface of the whole Baltic Sea. The gulf nevertheless provides
relatively large impact to the Baltic Sea through its drainage area (420,990 km 2 , i.e.,
about 20 % of the total drainage area of the Baltic Sea) and associated voluminous
river runoff.
The Gulf of Finland has no sill towards the Gotland Sea (Fig. 6.2). Topographically, the gulf is a direct continuation of the Northern Gotland Basin and just becomes shallower toward its eastern end. Its western boundary has been defined
historically (Witting 1910) as the line between Estonia and Finland: Põõsaspea–
Osmussaar–Hanko town. The deepest areas (80–100 m) are located in the western
and southern parts, the maximum depth (Paldiski Deep, the unofficial name of a
gap located just outside the town of Paldiski, Estonia) being 123 m (Leppäranta and
Myrberg 2009). The central part of the gulf is quite deep (over 60 m) until longitude 28° E and has uninterrupted deep-water connection with the northern Gotland
Sea. The complicated shape of deeper areas (Andrejev et al. 2010) enhances the
challenge to adequately replicate the dynamics of water masses in this basin.
Various parts of the gulf have very different geometric and bathymetric properties. The Finnish nearshore is a typical example of a skären-type coast. Its ex-
185
Fig. 6.1 Scheme of the Gulf of Finland. Graphics by M. Viška
6.2 General Features of the Gulf of Finland Affecting
the Circulation Dynamics: The Forcing
6.2.1 Topography
The elongated, narrow and relatively shallow Gulf of Finland is the easternmost
basin in the Baltic Sea, surrounded by Finland, Russia and Estonia (Fig. 6.1). The
gulf lies between 59°11 N, 22°50 E and 60°46 N, 30°20 E (Alenius et al. 1998;
Leppäranta and Myrberg 2009). Even in the Baltic Sea scales, it is a relatively small
basin. Its length is about 400 km and the width varies from 48 km between Tallinn
and Porkkala to 135 km between Narva Bay and Kotka. Its volume and surface
area (1,103 km 3 and 29,948 km 2 , respectively) are about 5 % of the volume and
about 7.5 % of the surface of the whole Baltic Sea. The gulf nevertheless provides
relatively large impact to the Baltic Sea through its drainage area (420,990 km 2 , i.e.,
about 20 % of the total drainage area of the Baltic Sea) and associated voluminous
river runoff.
The Gulf of Finland has no sill towards the Gotland Sea (Fig. 6.2). Topographically, the gulf is a direct continuation of the Northern Gotland Basin and just becomes shallower toward its eastern end. Its western boundary has been defined
historically (Witting 1910) as the line between Estonia and Finland: Põõsaspea–
Osmussaar–Hanko town. The deepest areas (80–100 m) are located in the western
and southern parts, the maximum depth (Paldiski Deep, the unofficial name of a
gap located just outside the town of Paldiski, Estonia) being 123 m (Leppäranta and
Myrberg 2009). The central part of the gulf is quite deep (over 60 m) until longitude 28° E and has uninterrupted deep-water connection with the northern Gotland
Sea. The complicated shape of deeper areas (Andrejev et al. 2010) enhances the
challenge to adequately replicate the dynamics of water masses in this basin.
Various parts of the gulf have very different geometric and bathymetric properties. The Finnish nearshore is a typical example of a skären-type coast. Its ex-