What currents are there in the Black Sea? Hydrographic map of the Black Sea Map of sea currents Crimea

Greetings, friends!

Crimea and the Black Sea are two inseparable and familiar concepts.

Do you know how many global rebirths and metamorphoses have happened to it over millions of years, what secrets fill its essence and how many different names the ancestors bestowed on its rebellious waters.

No? Then I ask for the article.

Today we will talk not only about its past and present, but also touch upon aspects that are important for tourists. I will also give 10 fascinating facts about the Black Sea.

The name “black” was firmly established only in the Middle Ages. The most ancient name known to us - Temarinda (dark abyss) was given by the Tauri. The ancient Greeks first christened it Pont Aksinsky (inhospitable sea), and when business got better - Pont Evskinsky (hospitable).

It bore other names, completely different from today’s name: Khazar, Polovtsian, Turkish, Eastern, Surozh, Tsargradskoe, Bolshoye and even Russian.

Its waters were plied by travelers of all stripes and nationalities: Strabo, Marco Polo, Afanasy Nikitin and others.

Our sea is mentioned in ancient Iranian texts as “Akhshaina”, in Turkish “Kara Deniz” and in German “Schwarze Mee”.

Creation of the Black Sea basin

As the Black Sea merged with the waters of other seas and oceans, was divided and torn apart by underwater ridges rising from the depths of the sea, nature was wondering whether to leave it as a fresh lake or create a salty water area.

As a result of the last global earthquake more than 7.5 thousand years ago, huge masses of salty water from the world's oceans poured into the almost fresh basin of our sea, thus thoroughly determining its status.

So even today the Black Sea is a branch of the Mediterranean and the easternmost sea of ​​the Atlantic basin. In addition, at one time the Black Sea was connected to the Caspian Sea several times.

During this time, a lot of water has flowed under the bridge - literally and figuratively, and the Black Sea, the most desirable and gentle for us in the heat, in the past, more than once showed all its power and merciless force, washing away ancient settlements rooted on the coasts from the face of the earth.

Such transformations could not but affect the flora and fauna of the underwater kingdom. The inevitable death of many species of freshwater inhabitants of the seabed and their subsequent decomposition resulted in the formation of large amounts of hydrogen sulfide.

The deepest sea in Europe

Today, the Black Sea is the deepest in Europe. Remains alive in the upper layers at a depth of 100-150m and dead in the lowest.

Surely, you all know what an important role the Black Sea plays in relation to our peninsula. This is, first of all, transport, military, strategic, and, of course, recreational significance.

Almost the entire Crimean coast is occupied by resort areas, washed by the Black Sea from the south and west. The incredible (pebble, sandy, wild, nudist) will always find its tourist.

But you need to know about the character and mood of its waters depending on the season and a little about its features.

The fullness of the Black Sea water area is clearly demonstrated by the map of depths and currents.

Thus, the shallowest sea is in the southwestern part, off the coast of Evpatoria and further along the northwestern coast. And the deepest place is the Yalta depression, almost in the central part of the basin.

Duration of the holiday season

The Black Sea is a unique natural body of water, with a changing landscape along the entire coastline.

There are mountain ranges with picturesque rocks, underwater grottoes and mysterious caves. There are endless steppes, practically devoid of vegetation, and plains with garden and park areas.

The sea temperature, thanks to the Mediterranean climate, allows the holiday season to last from mid-May to the end of October. But, depending on the month and atmospheric phenomena, it is prone to changes.

Water temperature by month

By the way, did you know that for almost 7 months of the year the sea temperature is warmer than the air temperature? This is why the effect of a mild climate in Crimea is created, when winter cannot take the reins into its own hands.

Beginning from mid-May , the water off the coast of the peninsula is gradually gaining solar heat.

June– already allows you to take water procedures.

Moreover, it is warmest at this time off the coast of Kerch (average temperature 20-20.5 degrees), as well as on the shallow beaches of Evpatoria, Sak and Chernomorskoe. It is cooler in both air and sea temperatures at this time on the South Coast.

The hottest month remains July, with stuffy nights and high temperatures along the entire Crimean coast.

But taking a dip in the water on the beaches of the South Coast, Sevastopol or Evpatoria, you can feel a difference of 2-3 degrees. The sea is relatively cold at this time in Sudak and Feodosia (up to 21-23 degrees).

Why do many people want their vacation in Crimea to be during August?

Yes, because this month the air and water temperatures are approximately the same. The sea is not stormy yet, and at night the long-awaited coolness sets in.

September- a glorious, velvet season. The sea, warmed up during the summer, is especially gentle, and reluctantly says goodbye to the warmth. And the autumn freshness is already slightly noticeable in the air. At this time, it is best in Yalta, cooler in the resorts of Sevastopol and Evpatoria. The warmest sea remains off the eastern shores.

The mostly clear, crystalline sea remains on the sparsely populated western and northern beaches. In particular, Cape Tarkhankut, favored by romantics, lovers of impressions and underwater exploration.

Features of the behavior of the Black Sea

Has it ever happened to you that when you come to Crimea on vacation on a hot July day, in anticipation you take a running plunge into absolutely cold water? Or having sailed a few meters from the shore, you feel a not very pleasant drop in temperature?

This is a common occurrence when reign sgony – nizovka , in other words – mixing of water layers.

The peculiarity is due to the rise of colder, deep waters, while the heated upper layers of the current are carried into the open sea space. And the reason for this is the continuous wind that blows from the land.

This behavior of the Black Sea is observed a couple of times during the summer, mainly in June - July and can last from 3 to 10 days.

But the good thing is that it is not everywhere, and at high temperatures the water warms up quickly. Most often, expulsions were recorded in July on the South Coast, in June - in Evpatoria and Feodosia.

If there is little time left for rest and there is no way to wait for the comfortable temperature to return, you can risk changing the beach. Most likely, you will be lucky and the last days of your vacation will not be overshadowed by the vagaries of natural phenomena.

In fact, you shouldn’t look at the phenomenon of “surges” so negatively. Thanks to them, the surface coastal layer of sea water is cleaned and replaced with fresher water. In general, this benefits both nature and us avid swimmers.

Blue color of the Black Sea

In 2018, a very interesting metamorphosis was recorded with the hitherto deep blue waters of our sea. This year they began to imitate the color of their neighbor the Mediterranean Sea.

Here is another photo from space that characterizes the strange colors.

Scientists blamed everything on phytoplankton, which through its vital activity led to such turquoise consequences.

But, to be honest, there is nothing to be particularly happy about here, since in addition to the change in color, the transparency of the water has also changed. Now it feels like there is some kind of suspension in it and it has become more difficult to admire the underwater expanses through the mask.

Here we are on the run from Balaklava to Cape Aya. The color of the water hurts your eyes!

But not only the Black Sea changed color, but also the neighboring Bosporus Strait. The Turkish waters of the Istanbul region have also begun to raise questions and alarming views.

Let's see what the picture of the famous strategic strait looks like from space:

By the way, note that not all areas are colored, namely the flow component. That is, most likely, these bacteria came to us from somewhere along the movement of water masses.

It is worth knowing that the Black Sea belongs to the Atlantic Ocean basin, although it is quite far from it.

The chain of connections looks like this: Atlantic Ocean - Gibraltar - Mediterranean Sea - Aegean Sea - Dardanelles - Sea of ​​Marmara - Bosphorus - Black Sea.

So there you go! Latest news from the fields! Friends noticed that the color of the water on the Portuguese coast also changed and turned azure.

So maybe this is all the migration of plankton from the Atlantic Ocean?

10 facts about the Black Sea

1. Yes, in the Black Sea There issharks But this katran shark itself is afraid of humans and is of interest only to fishermen. Katran's liver contains substances used in cancer drugs
2. The Black Sea is secretly called the “sea of ​​dead depths.” Due to the presence of hydrogen sulfide deeper than 150 meters there is no life at sea . This is said by all the troupes of freshwater inhabitants who died during the flood. Biblical???
3. In the Black Sea they live only 2500 species of animals , since in the neighboring Mediterranean there are more than 9,000.
4. In the Black Sea there are only 3 more or less big islands : Dzharylchag - 62 sq. km, Berezan and Zmeiny - less than 1 sq. km.
5. Black Sea not very salty in comparison with other seas, only 18 g of salt per 1 kg of water or 1.018. The Mediterranean Sea, like the Aegean Sea - 1.038, the Red Sea - 1.042, the White Sea - 1.030. I won't mention the Dead Sea. But the Baltic is considered the freshest - 1.007.
6. A deep-sea " blue stream » from Russia to Turkey.
7. If you look at the current map above you will see " Knipovich glasses “—2 centrifugal flows of water in the form of glasses, named after the oceanologist Knipovich, who was the first to describe these currents.
8. Almost on the Black Sea no ebbs and flows due to the significant distance from the Atlantic Ocean.
9. Black Sea jellyfish are not dangerous , although contact with some may cause itching and burning. Be sure to wash your hands after handling them and avoid getting into your eyes.
10. October 31 - International Black Sea Day is celebrated in the coastal countries of the Black Sea basin. The date coincides with the signing in 1996 by the countries of Bulgaria, Georgia, Romania, Turkey, Ukraine and Russia of the Strategic Plan for the Development and Restoration of the Black Sea. Every year on this day, various environmental campaigns and beach clean-up companies are held.

Don't forget the beaches

Since the article has come to an end, and we are overwhelmed with information about the beaches, I suggest continuing to read this section ““. And if you are looking for adventures on your own, then they are all conveniently collected in one place on the Turnado website.

Friends, that's all for today. Subscribe to the blog and always read fresh and interesting articles. Also, don't forget to write your valid comments and observations from your experience.

Black Sea Currents

The results of our studies of the currents of the Northern and Middle Caspian Sea differed significantly from the ideas that were most widespread. Therefore, we sought to compare them with published results from studies in other bodies of water. Gradually, we moved from studies of Caspian currents to studies of the nature of specific types of currents - wind, thermohaline, quasi-permanent circulations, long-wave, inertial, etc. in various reservoirs - in the Black Sea, in the Sea of ​​Okhotsk, in lakes Ladoga, Huron, etc. ., in those reservoirs for which it is possible to find measurement results.

This approach significantly expands the amount of experimental data suitable for analysis. We can compare current parameters in different bodies of water. This will allow us to better understand the properties of the studied processes of formation and existence of flows. The main research methods were invented during studies of the currents of the Northern and Middle Caspian Sea.

Let us consider the results of instrumental observations of currents in various seas and large lakes.

2.1. Black Sea Currents

The area of ​​the Black Sea is 423,488 km. The greatest width along the parallel is 42°21′ N. – 1148 km, along the meridian 31°12′ E – 615 km. Coastline length 4074 km.

Rice. 2.1. Black Sea water circulation diagram. 1 – Annular cyclonic current (ACC) – average position of the rod; 2 – CCT meanders; 3 – coastal anticyclonic eddies (SAEs); 4 – cyclonic eddies (CV); 5 – Batumi anticyclonic vortex; 6 – Kaliar surfactant; 7 – Sevastopol surfactant; 8 – Kerch surfactant; 9 – quasi-stationary cyclonic gyres (Kosyan R.D. et al. 2003).

The general circulation of the Black Sea waters - the Main Black Sea Current (Rim Current) is characterized by cyclonic movement of waters (Fig. 2.1). Its main structural element is the Annular Cyclonic Current (RCC). Near the Caucasian coast, the CCT occupies a strip along the coast 50-60 km wide and carries its waters in a general direction to the northwest. The centerline of the flow can be traced at a distance of 20-35 km from the coast, where speeds reach 60-80 cm/s. This current penetrates to a depth of 150-200 m in the summer, 250-300 m in the winter, sometimes to a depth of 350-400 m. The current core experiences wave-like oscillations, deviates either to the right or to the left from its average position, i.e. This jet the current meanders. In Fig. 2.1. the most common idea of ​​the structure of the Black Sea currents is presented.

The results of current measurements carried out over a period of 5 months in coastal waters in the northeastern part of the Black Sea are shown in Fig. 2.2.

In the figures we see that the currents cover the entire water column, the changes are synchronous at all horizons.

Rice. 2.2. Fragment of the time sequence of half-hour current vectors from December 20 to December 23, 1997. Point 1 – horizons of 5, 26 and 48 m; point 2 – horizons 5 and 26 m; point 3 – horizon 10 m (Kosyan R.D. et al. 2003).

These studies did not filter to identify long-period wave currents. The measurements lasted 5 months, i.e. It is possible to show about 5 periods of variability of long-period wave currents and their variability at different points, differences and common features as they move away from the coast. Instead, the authors provide explanations that are consistent with traditional views.

Rice. 2.3. Location of instruments off the southern coast of the Crimean Peninsula at points 1–5 (Ivanov V. A., Yankovsky A. E. 1993).

Rice. 2.4. Variability of current speed at measurement points 3 and 5 (Fig. 2.12) at a horizon of 50 m. High-frequency oscillations with a period of 18 hours. And less filtered using a Gaussian filter. (Ivanov V. A., Yankovsky A. E. 1993).

Measurements of currents in the coastal zone using autonomous buoy stations (ABS) were carried out off the southern coast of the Crimean Peninsula in the Black Sea at 6 points on 4 horizons from June to September 1991 (Fig. 2.3). (Ivanov V. A., Yankovsky A. E. 1993).

One of the main tasks is the study of waves captured by the shore. Long-wave currents with a period of 250-300 hours have been recorded. and amplitude up to 40 cm/s (Fig. 2.4). The phase propagated westward at a speed of 2 m/s. (Note that the value of the phase velocity is obtained from calculation, and not from the difference in the time of passage of the wave at two adjacent points).

Water circulation in the upper layer of the Black Sea is shown using drift data (Zhurbas V.M. et al. 2004). More than 61 drifters were launched in the Black Sea, which were carried by the current of large-scale circulation along the coast.

Rice. 2.5. Trajectory of drifter No. 16331 in the southwestern part of the Black Sea. The numbers on the trajectory are the day that has passed since the drifter was launched (Zhurbas V.M. et al. 2004).

The patterns of drifter advancement show the patterns of currents. The most common misconception about the nature of currents in the Black Sea: cyclonic circulation currents are jet meandering current. Meanders, breaking away from the main jet, form vortices. The authors demonstrate such a “vortex” in Fig. 2.5.

The following figure (2.6) shows the variability of the components of the speed of movement (current) of the drifter along the trajectory. The periodic variability of the current speed is clearly visible. The period of variability is from 2 to 7 days. The speed varies from - 40 cm/s. up to 50 cm/s, but the average speed (thick line) is close to zero. The drifter moves along a circular path. It reflects the movement of a water mass of a wave nature.

Bondarenko A.L. (2010) shows the path of one of the drifters in the Black Sea (Fig. 2.7), and the variability of the speed of the drifter’s movement along the trajectory (Fig. 2.8). Just as in the previous work, it is clear that currents of a wave nature are observed, and not a jet, meandering current. The path taken by the drifter during the initial period of its voyage attracts attention. The starting point (0) is in the center of the western part of the sea.

Rice. 2.6. Time series of drifter velocity components 16331. Ut is the longitudinal component of the velocity (+/- east/west, respectively), Vt is the latitudinal component [Zhurbas V.M. et al. 2004].

According to ideas (Fig. 2.1), this point is located outside the CCT. But we see that the drifter made a cyclonic path along a stretched almost ellipse, then moved southwest for 20 days. the direction where he got into the CCT and moved in it the entire further path. From this trajectory it is possible to calculate the flow velocity in different sections of the trajectory, and from (Fig. 2.8) the periodicity of the r.f. and n.ch. variability of this speed.

Rice. 2.7. Drifter's path in the Black Sea ( Bondarenko A.L., 2010).

The measurement examples discussed above show that the Main Black Sea Current, the Circular Cyclonic Current (ACC), is the resulting movement of long-period wave currents. The understanding of the geostrophic nature of the CCT currents and its meandering is erroneous. The period of variability of wave currents in the northern part is 260 hours. As we move along the coast, due to the unevenness of the coastline and bottom surface, the components of the current velocity across the coast become comparable with the components along the coast, the trajectories of drifters acquire a ring-shaped shape. The period of variability is greatly reduced.

Rice. 2.8. AND variability of the speed of movement of the drifter along the trajectory shown in Fig. 2.7.(Bondarenko A.L., 2010).

Many people who swim well or stay on the water well do not understand how you can drown near the shore when you know how to swim?! Especially when you don’t know how, and therefore you don’t go deeper than waist-deep. Having heard news reports during the holiday season about tourists who “died near the shore,” they think that the victims either did not know how to swim or were intoxicated. But they are wrong. What then is the reason?

We are talking about a very dangerous, but little-known phenomenon - rip currents, which are often also called “rip currents”. There are rip currents in all corners of the planet, in the Gulf of Mexico, the Black Sea, and the island of Bali. Not only ordinary people, but also first-class swimmers who do not know how to behave in this situation can not cope with these insidious rips. The most dangerous are considered to be rip currents in shallow seas with a gentle coast, which is framed by sandbanks, spits and islands (Azov sea, etc.). In these places, during low tide, sand spits prevent the return of the mass of water to the sea. The water pressure on the narrow strait connecting the sea with the estuary increases many times over. As a result, a fast flow is formed, through which water moves at a speed of 2.5-3.0 m/s.

You can read about the physics of the occurrence of “rips” yourself on your favorite Wikipedia. For technically incompetent comrades, it is enough to know that corridors with a reverse (seaward) current constantly appear in one place or another right next to the shore. There are “rips” that are stable, and they are not so dangerous, because, as a rule, all the locals know about them and tell them where not to go for a swim. But there are so-called flash rip currents that come and go; It is they who pose a mortal danger. In most cases, the "ripa" corridor is narrow, 2-3 meters, and it is easy to jump out of it to the right or left. Also, in most cases, the speed of the current in the “rip” is 4-5 km/h, which is also harmless. However, several times a day, “rips” up to 50 meters wide and up to 200-400 long can occur on the same beach! If you add a speed of 15 km/h to it, then, if you get into such a “rip”, if you don’t know how to deal with it, you can say a prayer. What happens when a person gets into a rip? He begins to be dragged into the open ocean. If the “rip” is wide and the speed is even minimal (5 km/h), it is useless to resist, that is, swim against the current - it will still drag you to the depths. The sad thing is that people who do not know about “rips” begin to desperately resist and frantically swim towards the shore, that is, against the current of the “rips”. Of course, nothing works out for them, and after 20-30 seconds a MONSTER PANIC begins! Can you imagine if a person doesn’t know how to swim?! Here he stands, say, waist-deep in water and thinks: “It’s a thrill! I won’t go any deeper, it’s safe here!” What is it! If she gets into a “rip”, she’ll be dragged away by the ocean and won’t ask for her last name, especially if she’s a weak woman or an elderly person. It will drag you to a place where there is no bottom... But you don’t know how to swim... It’s better not to think.

What should I do? How to deal with "rips"? If you don’t know how to swim at all, there is only one recommendation: don’t go into the water alone! Never! Only with someone experienced. Of course, you need to swim where there are lifeguards and red flags. Anyone who knows how to swim must remember that the depth up to the chest is already sufficient for a serious “rip” (10 km/h or more), which can drag you into the open ocean. What to do if you are still carried away? First and most importantly - DON'T PANIC! In no case, because if you know the rules of conduct in a “rip” and don’t panic, you will get out 100 times out of 100. The second main thing is not to resist the reverse current and under no circumstances swim to the shore! It sounds, of course, terrifying, but this is the only correct logic: by resisting, you will not achieve anything, you will still continue to drag, but in a minute or two you will be exhausted, exhausted, tired and guaranteed to lose your composure. Hundreds and hundreds of excellent swimmers, athletes, athletes, weightlifters and bodybuilders unknowingly drowned in “rips”. In this situation, the matter will not be yours. So, don't panic and swim to shore! What are you doing? First: you are trying to get out of the “rip” to the side. That is, you are not swimming towards the shore, but parallel to it. Right or left, it doesn't matter. If the “rip” is narrow, 2-4 meters, then you will quickly get out of it. If it is wide - up to 50 meters, then, of course, it will not work. As soon as you realize that you can’t get out, immediately stop trying and... relax! At least lie on your back, but don’t panic. Why? Because in a minute or two the oncoming current will end and leave you alone. After that, you will turn around and swim... but not immediately to the shore, but first 50-100 meters to the side in order to get around the “rip”, otherwise you will get stuck back into it. Oh, and while you're relaxingly floating with the flow, don't forget to raise your hand high, then at least a lifeguard will help you on the way back. Another important detail to remember: the “rip” will not drag you to the bottom! This is not a whirlpool or a funnel. All the “rips” in the world are dragged from the shore along the surface, but not to the depth.

Finally, the last thing: all “rips” have clear identification marks (signs). If there are no lifeguards with red flags on the beach, you can independently determine the location of the oncoming current by one of the following signs (in any combination). A visible channel of rushing water perpendicular to the shore. A coastal zone with a changed color of water (say, everything around is blue or green, and some area is white). An area of ​​foam, some kind of marine vegetation, bubbles, which is steadily moving from the shore into the open sea. A gap in the general structure of tidal waves (a continuous strip of waves, and a 5-10-meter gap in the middle). If you see any of the things described, consider yourself lucky and just don't go swimming in that place. What if you don't see any of the four signs? This means that you are out of luck, because 80 percent of dangerous spontaneously occurring “rips” (flash rips) do not manifest themselves visually. That is, professional rescuers will still be able to identify these places, but ordinary tourists are unlikely to. Until they get sucked into one of these invisible “rips”.

Located in the depths of the continent, the Black Sea (together with the Sea of ​​Azov) is the most isolated part of the World Ocean. In the southwest it communicates with the Sea of ​​Marmara through the Bosphorus Strait, the border between the seas runs along the line Rumeli Cape - Anadolu Cape. The Kerch Strait connects the Black and Azov Seas, the border between which is the line Cape Takil - Cape Panagia.

The area of ​​the Black Sea is 422 thousand km 2, the volume is 555 thousand km 3, the average depth is 1315 m, the greatest depth is 2210 m.

The coastline, with the exception of the north and northwest, is slightly indented. The eastern and southern shores are steep and mountainous, the western and northwestern shores are low and flat, steep in places. The only large peninsula is Crimean. In the east, spurs of the Greater and Lesser Caucasus ranges, separated by the Colchis Lowland, come close to the sea. The Pontic Mountains stretch along the southern coast. In the Bosphorus area, the shores are low but steep; in the southwest the Balkan Mountains approach the sea; further to the north is the Dobrudzha Upland, gradually turning into the lowlands of the vast Danube Delta. The northwestern and partially northern shores up to the mountainous southern coast of Crimea are low, dissected by ravines, extensive estuaries at the mouths of rivers (Dniester, Dnieper-Bug), fenced off from the sea by spits.

Beach near Pitsunda

In the northwestern part of the sea there are the largest bays - Odessa, Karkinitsky, Kalamitsky. In addition to them, on the southern coast of the sea there are Samsun and Sinop bays, and on the western coast - Burgas. The small islands of Zmeiny and Berezan are located in the northwestern part of the sea, Kefken - east of the Bosphorus.

The main part of the river flow (up to 80%) flows into the northwestern part of the sea, where the largest rivers carry water: Danube (200 km 3 / year), Dnieper (50 km 3 / year), Dniester (10 km 3 / year) . On the Black Sea coast of the Caucasus, the Inguri, Rioni, Chorokh and many small rivers flow into the sea. On the rest of the coast, the flow is negligible.

Climate

Remote from the ocean and surrounded by land, the Black Sea has a continental climate, which is manifested in large seasonal changes in air temperature. The climatic characteristics of individual parts of the sea are significantly influenced by orography - the nature of the relief of the coastal strip. Thus, in the northwestern part of the sea, open to the influence of air masses from the north, the climate of the steppes manifests itself (cold winters, hot, dry summers), and in the southeastern part, protected by high mountains, the climate of humid subtropics (abundant precipitation, warm winters, wet summer).

In winter, the sea is affected by the spur of the Siberian anticyclone, which causes intrusions of cold continental air. They are accompanied by northeastern winds (at a speed of 7 - 8 m/s), often reaching storm force, sharp drops in air temperature, and precipitation. Particularly strong northeastern winds are typical for the Novorossiysk (Bora) region. Here, masses of cold air accumulate behind the high coastal mountains and, having passed over the peaks, fall with great force down to the sea. The wind speed during bora reaches 30-40 m/s, the frequency of bora is up to 20 or more times a year. When the spur of the Siberian anticyclone weakens in winter, Mediterranean cyclones enter the Black Sea. They cause unstable weather with warm, sometimes very strong southwesterly winds and temperature fluctuations.

In summer, the influence of the Azores High spreads to the sea, clear, dry and hot weather sets in, and thermal conditions become uniform throughout the entire water area. During this season, weak northwestern winds (2-5 m/s) predominate; only in rare cases do northeastern winds of storm force occur in the coastal strip of the northeastern part of the sea.

The lowest temperature in January - February is observed in the northwestern part of the sea (-1-5°), on the southern coast of Crimea it rises to 4°, and in the east and south - to 6-9°. Minimum temperatures in the northern part of the sea reach -25 - 30°, in the southern part -5 - 10°. In summer, the air temperature is 23 - 25°, maximum values ​​at different points reach 35-37°.

Atmospheric precipitation falls very unevenly on the coast. In the southeastern part of the sea, where the Caucasus ridges block the path of the western and southwestern humid Mediterranean winds, the greatest amount of precipitation falls (in Batumi - up to 2500 mm/year, in Poti - 1600 mm/year); on the flat northwestern coast it is only 300 mm/year, off the southern and western coasts and on the southern coast of Crimea - 600-700 mm/year. 340-360 km 3 of Black Sea water flows annually through the Bosphorus, and about 170 km 3 of Mediterranean water enters the Black Sea. Water exchange through the Bosphorus experiences seasonal changes, determined by the difference in levels of the Black and Marmara Seas and the nature of the winds in the area of ​​the strait. The Upper Bosphorus current from the Black Sea (occupying a layer of about 40 m at the entrance to the strait) reaches its maximum in summer, and its minimum is observed in autumn. The intensity of the Lower Bosphorus current into the Black Sea is greatest in autumn and spring, least in early summer. In accordance with the nature of wind activity over the sea, strong waves most often develop in autumn and winter in the northwestern, northeastern and central parts of the sea. Depending on the wind speed and wave acceleration length, waves with a height of 1-3 m predominate in the sea. In open areas, maximum wave heights reach 7 m, and in very strong storms they can be higher. The southwestern and southeastern parts of the sea are the calmest; strong waves are rarely observed here, and there are almost no waves over 3 m high.

Crimean coast

Seasonal changes in sea level are created mainly due to intra-annual differences in river flow input. Therefore, in the warm season the level is higher, in the cold season it is lower. The magnitude of these fluctuations is not the same and is most significant in areas influenced by continental runoff, where it reaches 30-40 cm.

The greatest magnitude in the Black Sea is caused by surge level fluctuations associated with the influence of stable winds. They are especially often observed in autumn-winter in the western and northwestern parts of the sea, where they can exceed 1 m. In the west, strong surges are caused by easterly and northeasterly winds, and in the northwest - southeasterly ones. Strong surges in these parts of the sea occur during northwestern winds. Along the Crimean and Caucasian coasts, surges and surges rarely exceed 30-40 cm. Usually their duration is 3-5 days, but sometimes it can be longer.

In the Black Sea, seiche level fluctuations up to 10 cm in height are often observed. Seiches with periods of 2-6 hours are excited by wind, and 12-hour seiches are associated with tides. The Black Sea is characterized by irregular semidiurnal tides.

Ice cover

Ice is formed annually only in a narrow coastal strip in the northwestern part of the sea. Even in severe winters it covers less than 5%, and in moderate winters - 0.5-1.5% of the sea area. In very severe winters, the fast ice along the western coast extends to Constanta, and the floating ice is carried to the Bosphorus. Over the past 150 years, ice floes in the strait have been observed 5 times. In mild winters, only estuaries and individual bays are covered with ice.

Ice formation usually begins in mid-December, with maximum ice expansion observed in February. The boundary of stationary ice in moderate winters in the northwestern part of the sea runs from the Dniester estuary to the Tendrovskaya spit at a distance of 5-10 km from the coast. Further, the ice edge crosses the Karkinitsky Bay and reaches the middle part of the Tarkhankut Peninsula. Clearing of the sea from ice occurs in March (early - in early March, later - in early April). The duration of the ice period varies greatly: from 130 days in very severe winters to 40 days in mild ones. The ice thickness on average does not exceed 15 cm, in severe winters it reaches 50 cm.

Bottom relief

Underwater canyon in the Black Sea

In the topography of the seabed, three main structures are clearly distinguished: the shelf, the continental slope and the deep-sea basin. The shelf occupies up to 25% of the total bottom area and is on average limited to depths of 100-120 m. It reaches its greatest width (more than 200 km) in the northwestern part of the sea, which is all located within the shelf zone. Almost along the entire length of the mountainous eastern and southern coasts of the sea, the shelf is very narrow (only a few kilometers), and in the southwestern part of the sea it is wider (tens of kilometers).

The continental slope, occupying up to 40% of the bottom area, descends to approximately 2000 m depth. It is steep and indented by underwater valleys and canyons. The bottom of the basin (35%) is a flat accumulative plain, the depth of which gradually increases towards the center.

Water circulation and currents

Water circulation throughout the year is cyclonic in nature with cyclonic gyres in the western and eastern parts of the sea and the main Black Sea alongshore current that goes around them. Seasonal changes in circulation are reflected in the speeds and details of this current system. The main Black Sea current and cyclonic gyres are most clearly expressed in winter and summer. In spring and autumn, water circulation becomes weaker and more complex in structure. In the southeastern part of the sea, a small anticyclonic gyre is formed in the summer.

In the water circulation system, three characteristic areas can be distinguished, the structure of currents in which is distinguished by its originality: the coastal part, the zone of the main Black Sea current and the open parts of the sea.

The boundaries of the coastal part of the sea are determined by the width of the shelf. The current regime here depends on local factors and is significantly variable in space and time.

The zone of the main Black Sea current, 40-80 km wide, is located above the continental slope. The currents in it are very stable and have a cyclonic orientation. Current speeds on the surface are 40-50 cm/s, sometimes exceeding 100 and even 150 cm/s (in the flow core). In the upper hundred-meter layer of the main current, velocities decrease slightly with depth; the maximum vertical gradients occur in the 100-200 m layer, below which the velocities slowly attenuate.

In open parts of the sea, currents are weak. Average velocities here do not exceed 5-15 cm/s on the surface, slightly decreasing with depth to 5 cm/s at horizons of 500-1000 m. The boundaries between these structural regions are quite arbitrary.

In the shallow northwestern part of the sea, circulation is mainly driven by the wind. Northern and northeastern winds determine the cyclonic nature of the currents, and winds from the western directions determine the anticyclonic nature. In accordance with the nature of the winds, the establishment of anticyclonic circulation is possible in the summer season.

The general circulation of sea waters is unidirectional to a depth of about 1000 m. In deeper layers it is very weak, and it is difficult to talk about its general nature.

An important feature of the main Black Sea current is its meandering, which can lead to the formation of isolated eddies that differ in temperature and salinity from the surrounding waters. The size of the eddies reaches 40-90 km; the phenomenon of eddy formation is essential for water exchange not only in the upper, but also in the deep layers of the sea.

Inertial currents with a period of 17-18 hours are widespread in the open sea. These currents influence mixing in the water column, since their speeds even in a layer of 500-1000 m can be 20-30 cm/s.

Water temperature and salinity

The water temperature on the sea surface in winter rises from –0.5-0° in the coastal areas of the north-western part to 7-8° in the central regions and 9-10° in the south-eastern part of the sea. In summer, the surface layer of water warms up to 23-26°. Only during surges can short-term significant drops in temperature occur (for example, off the southern coast of Crimea). During the period of sea warming, a temperature jump layer is formed at the lower boundary of wind mixing, limiting the spread of heat to the upper homogeneous layer.

Salinity on the surface is minimal all year round in the northwestern part of the sea, where the bulk of river water flows. In the estuary areas, salinity increases from 0-2 to 5-10‰, and in most of the open sea it is 17.5-18.3‰.

During the cold season, a vertical circulation develops in the sea, which by the end of winter covers a layer with a thickness of 30-50 m in central to 100-150 m in coastal areas. The waters cool most strongly in the northwestern part of the sea, from where they are distributed by currents at intermediate horizons throughout the sea and can reach areas farthest from the centers of cold. As a consequence of winter convection, with subsequent summer heating, a cold intermediate layer is formed in the sea. It persists throughout the year at horizons of 60-100 m and is distinguished by its temperature at the boundaries of 8°, and in the core - 6.5-7.5°.

Convective mixing in the Black Sea cannot extend deeper than 100-150 m due to an increase in salinity (and therefore density) in deeper layers as a result of the influx of salty Marmara Sea waters there. In the upper mixed layer, salinity increases slowly, and then at 100-150 m it sharply increases from 18.5 to 21‰. This is a permanent salinity jump layer (halocline).

Starting from horizons of 150-200 m, salinity and temperature slowly increase towards the bottom due to the influence of saltier and warmer Marble Sea waters entering the deeper layers. At the exit from the Bosphorus they have a salinity of 28-34‰ and a temperature of 13-15°, but quickly change their characteristics when mixed with Black Sea water. In the bottom layer, a slight increase in temperature also occurs due to geothermal heat influx from the seabed. Deep waters, located in a layer from 1000 m to the bottom and occupying more than 40% of the sea volume in the Black Sea in winter (II) and summer (VIII), are characterized by great constancy of temperature (8.5-9.2 °) and salinity (22- 22.4‰.

Vertical distribution of water temperature (1) and salinity (2)

Thus, the main components are distinguished in the vertical hydrological structure of the Black Sea waters:

an upper homogeneous layer and a seasonal (summer) thermocline, associated mainly with the process of wind mixing and the annual cycle of heat flow through the sea surface;

a cold intermediate layer with a minimum temperature in depth, which in the northwest and northeast of the sea arises as a result of autumn-winter convection, and in other areas is formed mainly by the transfer of cold waters by currents;

constant halocline - a layer of maximum increase in salinity with depth, located in the contact zone of the upper (Black Sea) and deep (Marmara) water masses;

deep layer - from 200 m to the bottom, where there are no seasonal changes in hydrological characteristics, and their spatial distribution is very uniform.

The processes occurring in these layers, their seasonal and interannual variability, determine the hydrological conditions of the Black Sea.

The Black Sea has a two-layer hydrochemical structure. Unlike other seas, only the upper well-mixed layer (0-50 m) is saturated with oxygen (7-8 ml/l). Deeper, the oxygen content begins to decrease rapidly, and already at horizons of 100-150 m it is equal to zero. Hydrogen sulfide appears at the same horizons, the amount of which increases with depth to 8-10 mg/l at a horizon of 1500 m, and then stabilizes towards the bottom. In the centers of the main cyclonic gyres, where water rises, the upper boundary of the hydrogen sulfide zone is located closer to the surface (70-100 m) than in coastal areas (100-150 m).

At the border between the oxygen and hydrogen sulfide zones there is an intermediate layer of the existence of oxygen and hydrogen sulfide, which represents the lower “limit of life” in the sea.

Vertical distribution of oxygen and hydrogen sulfide in the Black Sea. 1 - average oxygen content, 2 - average hydrogen sulfide content, 3 - deviation from the average

The spread of oxygen into the deep layers of the sea is hampered by large vertical density gradients in the contact zone of the Black Sea and Marmara Sea water masses, limiting convective mixing by the upper layer.

At the same time, the exchange of water in the Black Sea occurs between all layers, although slowly. Deep salty waters, constantly replenished by the lower Bosphorus current, gradually rise and mix with the upper layers, which flow into the Bosphorus with the upper current. This circulation maintains a relatively constant salinity ratio in the sea water column.

In the Black Sea, the following main processes are distinguished (Vodyanitsky V.A. et al.), causing vertical exchange in the water column: the rise of water in the centers of cyclonic gyres and the descent at their periphery; turbulent mixing and diffusion in the sea water column; autumn-winter convection in the upper layer; bottom convection due to heat flow from the bottom; mixing in synoptic eddies; surge phenomena in the coastal zone.

Estimates of the time of vertical water exchange in the sea are very approximate. This important issue requires further research.

As the main mechanism for the formation of hydrogen sulfide in the Black Sea, most authors accept the reduction of sulfuric acid compounds (sulfates) during the decomposition of organic residues (dead organisms) under the influence of sulfate-reducing microspira bacteria. This process is possible in any reservoir, but the hydrogen sulfide formed in them quickly oxidizes. It does not disappear in the Black Sea due to the slow exchange of waters and the lack of possibility of its rapid oxidation in the deep layers. When deep water rises into the upper oxygen layer of the sea, hydrogen sulfide is oxidized into sulfates. Thus, in the sea there is a steady equilibrium cycle of sulfur compounds, determined by the rate of water exchange and other hydrodynamic processes.

Currently, there is an opinion that in recent decades there has been a constant unidirectional rise (trend) of the upper boundary of the hydrogen sulfide zone to the sea surface, reaching tens of meters. This is associated with anthropogenic withdrawals of river flow and changes in the density structure of the sea. However, the available data so far only indicate natural interannual fluctuations in the position of the boundary of the hydrogen sulfide zone, which occur differently in different areas of the sea. Isolating an anthropogenic trend against the background of these fluctuations is difficult due to the lack of systematic observations of the topography of the boundary of the hydrogen sulfide layer and the imperfection of the methodology for its determination.

Fauna and environmental issues

The diverse flora and fauna of the Black Sea are almost entirely concentrated in the upper layer 150-200 m thick, constituting 10-15% of the sea's volume. The deep water column, devoid of oxygen and containing hydrogen sulfide, is almost lifeless and inhabited only by anaerobic bacteria.

The ichthyofauna of the Black Sea was formed from representatives of different origins and includes about 160 species of fish. One of the groups is fish of freshwater origin: bream, crucian carp, perch, rudd, pike perch, ram and others, found mainly in the northwestern part of the sea. In desalinated areas and brackish-water estuaries there are representatives of ancient fauna that have been preserved since the existence of the ancient Ponto-Caspian basin. The most valuable of them are sturgeon, as well as several types of herring. The third group of Black Sea fish consists of immigrants from the North Atlantic - these are cold-loving sprat, whiting, spiny dogfish shark, etc. The fourth, largest group of fish - Mediterranean invaders - has over a hundred species. Many of them enter the Black Sea only in summer, and winter in the Marmara and Mediterranean Seas. These include bonito, mackerel, tuna, Atlantic horse mackerel, etc. Only 60 species of fish of Mediterranean origin that permanently live in the Black Sea can be considered Black Sea. These include anchovy, garfish, mullet, mackerel, red mullet, mackerel, flounder, stingrays, etc. Of the 20 commercial species of Black Sea fish, only anchovy, small mackerel and sprat, as well as the katran shark, are important.

Currently, the state of the Black Sea ecosystem is unfavorable. The species composition of plants and animals is depleted, and the stocks of useful species are reduced. This is primarily observed in shelf areas experiencing significant anthropogenic pressure. The greatest changes are observed in the northwestern part of the sea. A large amount of biogenic and organic substances coming here with continental runoff causes the massive development of planktonic algae (“blooming”). In the area influenced by the Danube runoff, the biomass of phytoplankton increased 10-20 times, cases "red tides". Due to the toxic effect of some algae, the death of fauna is observed during mass blooms. In addition, with the intensive development of plankton, a large number of dead organisms settle to the bottom, the decomposition of which consumes dissolved oxygen. With a well-defined stratification of waters, which prevents the flow of oxygen from the surface layer to the bottom layer, oxygen deficiency develops in it (hypoxia), which can lead to the death of organisms (deaths). Since 1970, death tolls of varying intensity have been repeated almost every year. Unfavorable environmental conditions have caused the death of a once vast field of phyllophora - an algae used to make agar-agar.

The deterioration of water quality and oxygen conditions is one of the main reasons for the decline in the number of commercial fish in the northwestern part of the Black Sea.

Currents in the sea can be figuratively compared to rivers without banks. In marine science, it is customary to designate the direction of currents using the “where” principle. Unlike currents, wind and wave directions are determined by the “from” principle. For example, a wind blowing from south to north will be called south, and the current created by this wind will be called north.

Map of Black Sea currents

The currents of the Black Sea are weak, their speed rarely exceeds 0.5 meters per second, their main causes are river flow and the influence of winds. Under the influence of river flow, the water should move towards the center of the sea, but under the influence of the force of the Earth's rotation, it deviates to the right (in the northern hemisphere) by 90 degrees and flows along the coast in a counterclockwise direction. The main stream of currents has a width of 40-60 kilometers and passes at a distance of 3-7 kilometers from the coast.

Separate gyres are formed in the bays, directed clockwise, their speed reaches 0.5 meters per second.
In the central part of the sea there is a calm zone, where the currents are weaker than off the coast and are not constant in direction. Some researchers identify two separate rings in the general flow. The origin of the two rings of currents is associated with the peculiarities of the outlines of the Black Sea, which contribute to the deviation of parts of the general flow to the left off the coast of Crimea and Turkey.

An interesting system of currents is observed in the Bosphorus Strait; it is of great importance for the Black Sea.

These currents were first studied at the end of the last century by Admiral Makarov. S. O. Makarov was not only an outstanding naval commander, shipbuilder, and military theorist, he was also a remarkable scientist who understood how important it is to understand the environment in which the navy had to operate.

From conversations with local residents, S. O. Makarov established that there are two currents in the Bosphorus: surface and deep. He tested this fact by successively lowering a load into the water to different depths. The load was secured by a cable to a buoy floating on the surface. When the load was in the surface layers, the buoy moved towards the Sea of ​​Marmara; when the load was at the bottom, the buoy was carried towards the Black Sea. Thus, it was established that the surface current, carrying desalinated water, goes to the Sea of ​​Marmara, and the deep one, carrying denser salty water, goes to the Black Sea. S. O. Makarov established that the speed of the upper current is 1.5 meters per second, the lower one is 0.75 meters per second; The depth of the current interface is 20 meters. The lower current does not go strictly under the upper one, both of them are reflected from the capes, sometimes the current jets bifurcate.

To explain the reasons for these currents, Makarov performed the following experiment. Water was poured into a glass box, divided into two parts: salted in one part, desalinated in the other. Two holes were made in the partition, one above the other. Salt water began to move through the lower hole, desalinated water through the top. S. O. Makarov was the first to explain the origin of these two layers. The upper current is a waste stream; it is formed under the influence of excess water brought by rivers to the Black Sea. The lower one, the so-called dense one, is formed as a result of the fact that the denser waters of the Sea of ​​Marmara exert greater pressure on the underlying layers than the lighter waters of the Black Sea. This causes water to move from an area of ​​higher pressure to an area of ​​lower pressure.