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E.V. Stanev and X. Lu
The difference, which is the total annual outflow of 473 km 3 /yr, is due to the positive fresh water budget consisting of annual runoff, precipitation and evaporation of
about 436 km 3 , 224 km 3 and 184 km 3 , correspondingly (HELCOM 1986).
Estimates of the river runoff in the Mediterranean Sea (Table 5.1) are in the range
of 250–500 km 3 /yr (Struglia et al. 2004), which is equivalent to 8.1–16 × 10 3 m 3 /s.
Basin-averaged precipitation during the period 1979–1993, as estimated by Mariotti
et al. (2002), shows annual mean values ranging from 331 to 477 mm/yr. Evaporation is in the range of 934–1176 mm/yr. Water loss to the atmosphere exceeds the
river input resulting in a Mediterranean fresh water deficit of about 500 mm/yr,
which for a total area of 2.5 million km 2 gives 1250 km 3 /yr. This number is only
four times larger than the net transport from the Black Sea. Keeping in mind that the
salinity difference between the surface and deep flows in the Bosporus Straits (36
against 18) is much larger than in Gibraltar (38 against 36), one could conclude that
the two straits control the salinity budget in the Mediterranean Sea almost equally.
5.1.2 The Role of Topography
The Black Sea (not including the Azov Sea) and the Baltic Sea (including the Kattegat) are the largest brackish seas in the world with a total area of 436,400 km 2
and 415,000 km 2 , and volumes of 547,000 km 3 and 21,700 km 3 , correspondingly
(Table 5.1). The Mediterranean Sea covers an approximate area of 2.5 million km 2
and has a volume of 3.7 million km 3 . The complex bathymetry and geometry of the
Baltic and Mediterranean Seas largely shape the geophysical flows, making them
strongly dependent on the regional geometries (Fig. 5.2). However, the principal
difference between these two basins is that the Mediterranean Sea is a deep oceantype basin (mean and maximum depth of 1,500 m and 5,267 m, correspondingly),
while the Baltic Sea is very shallow (mean and maximum depth of 55 m and 459 m,
correspondingly, see Chap. 2 for more detailed information). On the contrary, in
the Black Sea, which is also a deep basin, both large-scale topography and coasts
are relatively simple (Fig. 5.2). However, an extreme topographic slope combined
with deep canyons along the southern and eastern coasts, a large shallow shelf in the
north and a mild continental slope in the north-western part make the topographic
controls in the Black Sea rather different from what is known for the Baltic Sea, see
for instance Stanev (2005).
The small depths of the straits exert an important control on the inter-basin exchanges. The latter depend largely on the variations in precipitation and evaporation
over the watersheds. Because the rate between runoff and basin volume is much
larger for the Black and Baltic Seas compared to the one for the Mediterranean Sea,
the water exchange between Black Sea and Mediterranean Sea and Baltic Sea and
Atlantic Ocean are more sensitive to changes in river runoff in their catchment areas. Thus by integrating the variations of global forcing over vast catchment areas
(Fig. 5.1), the Black and Baltic Seas make large-scale climatic signals very clear
(Stanev and Peneva 2002; Hünicke et al. 2010).
E.V. Stanev and X. Lu
The difference, which is the total annual outflow of 473 km 3 /yr, is due to the positive fresh water budget consisting of annual runoff, precipitation and evaporation of
about 436 km 3 , 224 km 3 and 184 km 3 , correspondingly (HELCOM 1986).
Estimates of the river runoff in the Mediterranean Sea (Table 5.1) are in the range
of 250–500 km 3 /yr (Struglia et al. 2004), which is equivalent to 8.1–16 × 10 3 m 3 /s.
Basin-averaged precipitation during the period 1979–1993, as estimated by Mariotti
et al. (2002), shows annual mean values ranging from 331 to 477 mm/yr. Evaporation is in the range of 934–1176 mm/yr. Water loss to the atmosphere exceeds the
river input resulting in a Mediterranean fresh water deficit of about 500 mm/yr,
which for a total area of 2.5 million km 2 gives 1250 km 3 /yr. This number is only
four times larger than the net transport from the Black Sea. Keeping in mind that the
salinity difference between the surface and deep flows in the Bosporus Straits (36
against 18) is much larger than in Gibraltar (38 against 36), one could conclude that
the two straits control the salinity budget in the Mediterranean Sea almost equally.
5.1.2 The Role of Topography
The Black Sea (not including the Azov Sea) and the Baltic Sea (including the Kattegat) are the largest brackish seas in the world with a total area of 436,400 km 2
and 415,000 km 2 , and volumes of 547,000 km 3 and 21,700 km 3 , correspondingly
(Table 5.1). The Mediterranean Sea covers an approximate area of 2.5 million km 2
and has a volume of 3.7 million km 3 . The complex bathymetry and geometry of the
Baltic and Mediterranean Seas largely shape the geophysical flows, making them
strongly dependent on the regional geometries (Fig. 5.2). However, the principal
difference between these two basins is that the Mediterranean Sea is a deep oceantype basin (mean and maximum depth of 1,500 m and 5,267 m, correspondingly),
while the Baltic Sea is very shallow (mean and maximum depth of 55 m and 459 m,
correspondingly, see Chap. 2 for more detailed information). On the contrary, in
the Black Sea, which is also a deep basin, both large-scale topography and coasts
are relatively simple (Fig. 5.2). However, an extreme topographic slope combined
with deep canyons along the southern and eastern coasts, a large shallow shelf in the
north and a mild continental slope in the north-western part make the topographic
controls in the Black Sea rather different from what is known for the Baltic Sea, see
for instance Stanev (2005).
The small depths of the straits exert an important control on the inter-basin exchanges. The latter depend largely on the variations in precipitation and evaporation
over the watersheds. Because the rate between runoff and basin volume is much
larger for the Black and Baltic Seas compared to the one for the Mediterranean Sea,
the water exchange between Black Sea and Mediterranean Sea and Baltic Sea and
Atlantic Ocean are more sensitive to changes in river runoff in their catchment areas. Thus by integrating the variations of global forcing over vast catchment areas
(Fig. 5.1), the Black and Baltic Seas make large-scale climatic signals very clear
(Stanev and Peneva 2002; Hünicke et al. 2010).