Currents of the Mediterranean sea
The Mediterranean sea stretches from West to East from 5.5° W D. to 36° e and is located between the Parallels of 30 and 45° N. lat. Its southern coast belongs to the African continent, and the Western, Northern and Eastern Eurasia. This is the most secluded pool of the World ocean (Fig. 2.15). It belongs to the Atlantic ocean, but connected with it only by the narrow Strait of Gibraltar with depths of from 280 to 320 m In the North-East through Dardanely, the Marmara sea and the Bosphorus. where the depth reaches only 50-60 and 30-40 m respectively, it communicates with the Black sea. It is believed that the limited water exchange with other basins of the World ocean is one of the main reasons for the formation of the special hydrological regime. This understanding is based on the decisive role of the thermohaline circulations in the dynamics of the sea.
The Mediterranean sea is composed of many separate parts. Tyrrhenian sea, the Algerian-Provencal basin, the Alborán sea, Balearic (Iberian) sea, Gulf of lion, Ligurian sea, the Central basin (between the Sicilian Straits and the Cretan-African channel), Adriatic sea, Levantine Sea, Aegean sea (has a lot of Islands, and complex bottom topography). The Aegean sea are divided into 3 pools. Athos in the North, Chios in the middle part and most glubokinsky pool.
Fig. 2.15. Scheme long-term average circulation of the surface waters of the Mediterranean sea. (Ovchinnikov I. M. and others 1976).
Scheme long-term average circulation of surface waters is presented in (Fig. 2.15). Shows that, in General, in every part of the Mediterranean sea shows a cyclonic circulation.
It is of interest to see the result of the impact of tide-generating forces on the water mass of each part. According to the theory of Erie in each of the parts should occur rotational movement of the inclined surface of the sea around a fixed point. Such movement is shown to the East of the Tunisian Strait and in the Adriatic sea (Fig. 2.16).
But we must admit that these results are obtained by the calculation method. It would be interesting to show these alleged movements on measurements of variability. In accordance with the theory of Erie, each separate pool shall be observed the rotational motion of the inclined surface of the sea around a fixed point, which most likely generates the observed cyclonic circulation.
Fig. 2.16. The nature of the tides, the propagation of tidal waves and amplitude
siniging tide (Ovchinnikov and others 1976).
Fig. 2.17. The bathymetry of the area and the location of the Autonomous buoy stations
A, B, C, D, E, F. (Tsimplis M. N. and others . 2007).
Measurement of the variability of current velocities was carried out in 6 Greek arc Straits (Fig. 2.17) on three horizons at points A. B. C. D. E. F. ( Tsimplis M. N. and others 2007).
In Fig. 2.18 presents the variation of the velocity components across the Strait at 6 stations (1 – 6) on three horizons. For us it is important to note that the variability of flows has a periodic nature with an average period of about 4 days. We can assume that in the Greek pool ( Greatan Basin ) has its own cyclonic circulation in the form of a long-period wave currents with the characteristic wave period. In the Levantine basin ( Levantine Basin ) the periods of wave currents will be different. Therefore, in the Straits the current changes direction, oscillates mainly around the equilibrium position.
Fig. 2.18. The variability (component across the Strait). Positive rate means the flow of water in Greek pool. ( Tsimplis M. N. and others 2007).
Measure of variability of current velocities and wind were carried out along the continental shelf of the South-Eastern corner of the Mediterranean sea (Levantine sea) (Fig. 2.19) in the continuation of 10 years ( Zvi Rosentraub. Stephen Brenner 2007). The devices were installed in 10 locations along the coast of Israel (Fig. 2.19). In the data analysis used data from 3 weather stations on the shore.
The measurement results show that average monthly flows in the course of the year were largely directed to the North. Currents were strong during the storms of winter, decreased in spring, and reached up to scratch or had the direction of the South in the first two months of autumn. The authors attribute the observed changes in the velocities with the varying speed and wind direction. Wind effects explain the formation of upwelling .
The analysis of vector diagrams of velocities (Fig. 2.20) shows that in the area of location of the southern stations the direction of the current varies with an average period of 2-3 days, and a visual analysis shows that the flow oscillates about the equilibrium position, the constant component is small. It can be assumed that protekanie occurs in circular orbits (as in the South-Eastern part of the Black sea (Fig. 2.5, 2.7).
Fig. 2.19. The location of instruments, gauges currents, and weather stations along the coast.
In the area of the Northern stations (T3) in the middle of the shelf within basically the direction to the North (Fig. 2.19). The period of variability of current speed for about 3-4 days. For all horizons is updated synchronously. Confirmed by the cyclonic character of the circulation.
Fig. 2.20. Vector diagrams of wind and speed of currents at the two southern stations. ( Zvi Rosentraub. Stephen Brenner 2007).
Consider the results of studies ( Tsimplis M. N. and others 2007; Zvi Rosentraub. Stephen Brenner 2007) from the perspective of our understanding of the formation and existence of currents. The measurement data is small, compared to the number of separate pools. In Fig. 2.15 shows mainly cyclonic circulation in each basin (Ovchinnikov and others 1976). Measurement data ( Tsimplis M. N. and others 2007; Zvi Rosentraub. Stephen Brenner 2007) show that this circulation is the movement of long-period wave currents.