The water masses of the World Ocean can be divided into types characterized by certain properties or a certain ratio of various characteristics. The name of each Water mass reflects the area of ​​formation (source) and the ways of its movement. For example, Antarctic bottom water is formed in various areas around the Antarctic continent and is found near the bottom in large areas of the ocean. Water masses are formed either as a result of thermohaline changes due to the interaction of the sea and the atmosphere, or as a result of the mixing of two or more waters. After formation, the water mass shifts to a horizon determined by its density, depending on the vertical distribution of the density of the surrounding water, and, gradually mixing or interacting with the atmosphere (if the water mass spreads near the surface or on horizons close to the surface), loses feature(or features) that she acquired in the formation area.

The main water masses of the World Ocean are formed as a result of thermohaline changes. Such Water masses have an extremum in one or more characteristics. The layer in which this extremum is observed (the depth of the layer is determined by the density of water) is called the middle layer. This layer can be found in the study of the vertical distribution of the typical properties of V. m.

The largest part of the surface and subsurface water masses are the central water masses, which are found in temperate latitudes in both hemispheres. They are characterized by high salinity and rather high temperatures and can be subdivided into such subtypes as the western and eastern central water masses. These are precisely the water masses that are the source of the middle layer with a low salinity maximum (subtropical countercurrent), which is formed as a result of subsidence surface water in zones of subtropical convergence (35-40° N and S) in most tropical regions of the ocean. Between the central water masses of the northern and southern hemispheres is equatorial water. This water mass is well developed in the Pacific and Indian Oceans, but it is absent in the Atlantic Ocean.

In the direction towards the poles, the central water masses are cooling, which is associated with the melting of ice and the temperature contrast between water and the atmosphere. Between the polar surface water masses and deep waters there are waters of the intermediate zone—subarctic and subantarctic surface waters. At the junction of the water masses of the intermediate zone, the waters sink along the convergence zone. This zone, or polar front, can be considered as the area of ​​formation of intermediate water masses of the World Ocean. They are cold, have low salinity and separate the upper warm water sphere from the lower cold one. In the Atlantic Ocean, the most common intermediate water mass is the Antarctic intermediate water, which forms within the southern polar front; it can be traced by the "kernel method" up to 20°N. sh. To the north of this latitude there is a middle layer with a weakly pronounced salinity minimum.

Subarctic intermediate water occurs at more northerly latitudes, but is much less pronounced and does not spread as widely as Antarctic intermediate water.

Due to the shallowness of the Bering Strait, circulation between the Arctic Ocean and the North Pacific is limited; so the subarctic intermediate water in pacific ocean has a small distribution. However, off the coast of Russia, the waters sink and the formation of an intermediate water mass, very similar to the subarctic one; since this water mass is of Nearctic origin, it is called the North Pacific Intermediate Water.

Deep and bottom waters are formed in the polar regions, most actively around the Antarctic continent and in the regions adjacent to South Greenland. The influence of the Arctic Basin on the deep-water circulation of the World Ocean is insignificant due to the separation of the depths of the Arctic Basin by underwater ridges - rapids. It is assumed that the source of most of the deep and bottom waters is the Atlantic sector of the Southern Ocean (the Weddell Sea). Strong deep-sea circulation leads to the fact that the influence of the Atlantic Ocean is felt in most areas of the World Ocean. The Pacific Ocean does not have large sources of deep water and therefore the flow below 2000 m is probably weak. The Indian Ocean has a complex deep water system that depends more on the mixing of many other Water masses than on the formation of Water mass types as a result of thermohaline changes.

Formation water masses occurs in accordance with the geophysical conditions of individual regions of the World Ocean. In the process of genesis, significant volumes of water acquire a set of characteristic physicochemical and biological properties, which remains practically unchanged within the entire space of their distribution.

Properties

The main properties of water masses include salinity and temperature. Both of these indicators depend on climatic factors due to geographic latitude. Precipitation and evaporation play the main role in changing the salinity of waters. The temperature is influenced by the climate of the surrounding areas and ocean currents.

Types

In the structure of the World Ocean, the following types of water masses are distinguished - bottom, deep, intermediate and surface.

Surface masses formed under the influence of precipitation and fresh continental waters. This explains the constant changes in temperature and salinity. Waves and horizontal ocean currents also arise here. The layer thickness is 200–250 meters.

Intermediate water masses located at a depth of 500-1000 meters. They form in tropical latitudes, where high level salinity and evaporation.

Formation of deep masses caused by the mixing of surface and intermediate water masses. This type of water is found in tropical latitudes. Their horizontal speed can be up to 28 km per hour. The temperature at depths of more than 1000 meters is approximately +2–3 degrees.

Bottom water masses very low temperatures, constant salinity and high density. This type of water occupies that part of the ocean that is deeper than 3000 meters.

Kinds

Depending on the territorial location, there are such types of water masses as equatorial, tropical, subtropical, temperate and polar.

Equatorial water masses are characterized by: low density and salinity, high temperature (up to +28 degrees), low oxygen content.

Tropical masses of water are in the zone of influence of ocean currents. The salinity of such masses is higher, since evaporation prevails over precipitation here.

Moderate masses are desalinated by rivers, precipitation and icebergs. These latitudes are characterized by seasonal changes in water temperatures, and the average annual gradually decreases in the direction of the poles from 10 to zero degrees.

The salinity level in the polar layers is quite low, because the floating ice has a strong desalination effect. At a temperature of about -2 degrees, sea water of medium salinity freezes (the greater the salinity, the lower the freezing point).

What are water masses?

Answering the question, what are water masses, it makes sense to say about the processes taking place in the transition zones between them. When the masses meet, the waters mix, while the denser ones sink to a depth. Such areas are called convergence zones.

In the zones of divergence, there is a divergence of water masses, accompanied by the rise of water from the depths.

Just like air space, water space is heterogeneous in its zonal structure. About what is called the water mass, we will talk in this article. Let us identify their main types, as well as determine the key hydrothermal characteristics of ocean areas.

What is called the water mass of the oceans?

Water oceanic masses are relatively large layers of oceanic waters that have certain properties (depth, temperature, density, transparency, amount of salts contained, etc.) characteristic of this type of water space. The formation of the properties of a certain type of water masses occurs over a long period of time, which makes them relatively constant and the water masses are perceived as a whole.

The main characteristics of marine water masses

Water oceanic masses in the process of interaction with the atmosphere acquire various characteristics that differ depending on the degree of impact, as well as on the source of formation.

The main zones of the water masses of the oceans

The complex characteristics of water masses are formed under the influence of not only a territorial feature in combination with climatic conditions, but also due to the mixing of different water flows. The upper layers of ocean waters are more subject to mixing and atmospheric influence than the deeper layers of water of the same geographical region. In connection with this factor, the water masses of the World Ocean are divided into two large sections:

Types of waters of the oceanic troposphere

The oceanic troposphere is formed under the influence of a combination of dynamic factors: climate, precipitation, and the tide of continental waters. In this regard, surface waters have frequent fluctuations in temperature and salinity levels. The movement of water masses from one latitude to another forms the formation of warm and

In there is the greatest saturation with life forms in the form of fish and plankton. Types of water masses of the oceanic troposphere are usually subdivided according to geographical latitudes with a pronounced climatic factor. Let's name the main ones:

• Equatorial.
• Tropical.
• Subtropical.
• Subpolar.
• Polar.

Characteristics of equatorial water masses

The territorial zonality of equatorial water masses covers the geographical band from 0 to 5 north latitude. The equatorial climate is characterized by almost the same high temperature regime throughout the calendar year, therefore, the water masses of this region are warmed up to a sufficient degree, reaching a temperature mark of 26-28.

Due to heavy rainfall and inflow of fresh water river water from the mainland, equatorial ocean waters have a small percentage of salinity (up to 34.5‰) and the lowest relative density (22-23). The saturation of the aquatic environment of the region with oxygen also has the lowest indicator (3-4 ml/l) due to the high average annual temperature.

Characteristics of tropical water masses

The zone of tropical water masses occupies two bands: 5-35 of the northern hemisphere (north-tropical waters) and up to 30 of the southern hemisphere (south-tropical waters). They are formed under the influence of climate and air masses - trade winds.

The summer temperature maximum corresponds to the equatorial latitude, but in winter this figure drops to 18-20 above zero. The zone is characterized by the presence of ascending water flows from a depth of 50-100 meters near the western coastal continental lines and descending flows near the eastern coasts of the mainland.

Tropical types of water masses have a higher salinity index (35-35.5‰) and conditional density (24-26) than that of the equatorial zone. The oxygen saturation of tropical water flows remains approximately at the same level as that of the equatorial strip, but the saturation with phosphates exceeds: 1-2 µg-at/l versus 0.5-1 µg-at/l for equatorial waters.

Subtropical water masses

The temperature during the year of the subtropical water zone can drop to 15. In the tropical latitude, desalination of water occurs to a lesser extent than in other climatic zones, since there is little precipitation here, while intensive evaporation takes place.

Here the salinity of the waters can reach up to 38‰. The subtropical water masses of the ocean, when cooled in the winter season, give off a lot of heat, thereby making a significant contribution to the heat exchange process of the planet.

The boundaries of the subtropical zone reach approximately the 45th southern hemisphere and up to 50th north latitude. There is an increase in the saturation of water with oxygen, and hence with life forms.

Characteristics of subpolar water masses

As you move away from the equator, the temperature of water flows decreases and varies depending on the time of year. So in the territory of subpolar water masses (50-70 N and 45-60 S), in winter the water temperature drops to 5-7, and in summer it rises to 12-15 about S.

The salinity of water tends to decrease from subtropical water masses towards the poles. This is due to the melting of icebergs - sources of fresh water..

Characteristics and features of polar water masses

The localization of polar oceanic masses is near-continental polar northern and southern spaces, thus, oceanologists distinguish the presence of Arctic and Antarctic water masses. Distinctive features polar waters are, of course, the lowest temperature indicators: in summer, on average, 0, and in winter, 1.5-1.8 below zero, which also affects the density - here it is the highest.

In addition to temperature, low salinity (32-33‰) is also noted due to the melting of continental fresh glaciers. The waters of the polar latitudes are very rich in oxygen and phosphates, which favorably affects the diversity of the organic world.

Types and properties of water masses of the oceanic stratosphere

Oceanologists conventionally divide the oceanic stratosphere into three types:

1. Intermediate waters cover water layers at a depth of 300-500 m to 1000 m, and sometimes 2000 m. Compared to the other two types of water masses of the stratosphere, the intermediate layer is the most illuminated, warmest and more richer undersea world plankton and various types fish. Under the influence of the proximity to the water flows of the troposphere, which is dominated by a rapidly flowing water mass, the hydrothermal characteristics and the flow rate of the water flows of the intermediate layer are very dynamic. The general tendency of the movement of intermediate waters is observed in the direction from high latitudes to the equator. The thickness of the intermediate layer of the oceanic stratosphere is not the same everywhere; a wider layer is observed near the polar zones.
2. Deep waters have an area of ​​distribution, starting from a depth of 1000-1200 m, and reaching up to 5 km below sea level and are characterized by more constant hydrothermal data. The horizontal flow of water flows of this layer is much less than intermediate waters and is 0.2-0.8 cm/s.
3. The bottom layer of water is the least studied by oceanologists due to its inaccessibility, because they are located at a depth of more than 5 km from the surface of the water. The main features of the bottom layer are the almost constant level of salinity and high density.

water masses- These are large volumes of water that form in certain parts of the ocean and differ from each other in temperature, salinity, density, transparency, amount of oxygen and other properties. Unlike, in them great importance It has. Depending on the depth, there are:

Surface water masses. They are formed under the influence of atmospheric processes and influx fresh water from the mainland to a depth of 200-250 m. Salinity often changes here, and their horizontal transfer in the form of ocean currents is much stronger than the deep one. Surface waters have the highest content of plankton and fish;

Intermediate water masses. They have a lower limit within 500-1000 m. In tropical latitudes, intermediate water masses are formed under conditions of increased evaporation and constant rise. This explains the fact that intermediate waters occur between 20° and 60° in the northern and southern hemispheres;

Deep water masses. They are formed as a result of mixing of surface and intermediate, polar and tropical water masses. Their lower limit is 1200-5000 m. Vertically, these water masses move extremely slowly, and horizontally they move at a speed of 0.2-0.8 cm / s (28 m / h);

Bottom water masses. They occupy a zone below 5000 m and have a constant salinity, a very high density, and their horizontal movement is slower than vertical.

Depending on the origin, the following types of water masses are distinguished:

tropical. They form in tropical latitudes. The water temperature here is 20-25°. The temperature of tropical water masses is greatly influenced by ocean currents. The western parts of the oceans are warmer, where warm currents (see) come from the equator. The eastern parts of the oceans are colder, as cold currents come here. Seasonally, the temperature of tropical water masses varies by 4 °. The salinity of these water masses is much greater than that of the equatorial ones, since, as a result of descending air currents, little precipitation is established and falls here;

water masses. In the temperate latitudes of the Northern Hemisphere, the western parts of the oceans are cold, where cold currents pass. The eastern regions of the oceans are warmed by warm currents. Even in the winter months, the water in them has a temperature of 10°C to 0°C. In summer it varies from 10°С to 20°С. Thus, seasonally the temperature of moderate water masses varies by 10°C. They already have a change of seasons. But it comes later than on land, and is not so pronounced. The salinity of temperate water masses is lower than that of tropical ones, since not only rivers and precipitation that fall here, but also those entering these latitudes, have a desalination effect;

Polar water masses. Formed in and off the coast. These water masses can be carried by currents to temperate and even tropical latitudes. In the polar regions of both hemispheres, water cools down to -2°C, but still remains liquid. Further lowering leads to the formation of ice. The polar water masses are characterized by an abundance of floating ice, as well as ice that forms huge ice expanses. The ice stays all year round and is in constant drift. In the Southern Hemisphere, in regions of polar water masses, they enter temperate latitudes much further than in the Northern Hemisphere. The salinity of the polar water masses is low, since ice has a strong desalination effect. There are no clear boundaries between the listed water masses, but there are transition zones - zones of mutual influence of neighboring water masses. They are most clearly expressed in places where warm and cold currents meet. Each water mass is more or less homogeneous in its properties, but in transitional zones these characteristics can change dramatically.

Water masses actively interact with: they give it heat and moisture, absorb carbon dioxide from it, release oxygen.

WATER MASSES, a volume of water commensurate with the area and depth of a reservoir, with relative homogeneity of physical, chemical and biological characteristics, formed in specific physical and geographical conditions (usually on the surface of the ocean, sea), different from the surrounding water column. Features of water masses acquired in certain areas of the oceans and seas are preserved outside the area of ​​formation. Adjacent water masses are separated from each other by World Ocean front zones, separation zones and transformation zones, which can be traced along the increasing horizontal and vertical gradients of the main indicators of water masses. The main factors in the formation of water masses are the thermal and water balances of a given area, respectively, the main indicators of water masses are temperature, salinity, and the density that depends on them. The most important geographical patterns- horizontal and vertical zonality - appear in the ocean in the form of a specific structure of waters, consisting of a set of water masses.

In the vertical structure of the World Ocean, water masses are distinguished: surface - up to a depth of 150-200 m; subsurface - up to 400-500 m; intermediate - up to 1000-1500 m, deep - up to 2500-3500 m; bottom - below 3500 m. In each of the oceans there are water masses characteristic of them, surface water masses are named according to the climatic zone where they formed (for example, Pacific subarctic, Pacific tropical, and so on). For the underlying structural zones of the oceans and seas, the name of the water masses corresponds to their geographical area(Mediterranean intermediate water mass, North Atlantic deep, deep Black Sea, Antarctic bottom, etc.). The density of water and the characteristics of atmospheric circulation determine the depth to which the water mass sinks in the region of its formation. Often, when analyzing a water mass, indicators of the content of dissolved oxygen in it, other elements, the concentration of a number of isotopes are also taken into account, which make it possible to trace the spread of the water mass from the area of ​​its formation, the degree of mixing with surrounding waters, and the time spent out of contact with the atmosphere.

The characteristics of water masses do not remain constant, they are subject to seasonal (in the upper layer) and long-term fluctuations within certain limits, and change in space. As they move from the area of ​​formation, the water masses are transformed under the influence of the changed heat and water balances, the features of the circulation of the atmosphere and the ocean, and are mixed with the surrounding waters. As a result, primary water masses are distinguished (formed under the direct influence of the atmosphere, with the greatest fluctuations in characteristics) and secondary water masses (formed by mixing the primary ones, they are distinguished by the greatest uniformity of characteristics). Within the limits of the water mass, a core is distinguished - a layer with the least transformed characteristics that retains the characteristics inherent in a particular water mass. features- minimums or maximums of salinity and temperature, the content of a number of chemicals.

When studying water masses, the method of temperature-salinity curves (T, S-curves), the kernel method (study of the transformation of temperature or salinity extremes inherent in the water mass), the isopycnal method (analysis of characteristics on surfaces of equal density), statistical T, S-analysis are used. The circulation of water masses plays an important role in the energy and water balance of the Earth's climate system, redistributing thermal energy and freshened (or saline) water between latitudes and different oceans.

Lit.: Sverdrup H. U., Johnson M. W., Fleming R. H. The oceans. N.Y., 1942; Zubov N. N. Dynamic Oceanology. M.; L., 1947; Dobrovolsky A.D. On the determination of water masses // Oceanology. 1961. T. 1. Issue. 1; Stepanov V. N. Oceanosphere. M., 1983; Mamaev OI Thermohaline analysis of the waters of the World Ocean. L., 1987; he is. Physical Oceanography: Selected. works. M., 2000; Mikhailov V.N., Dobrovolsky A.D., Dobrolyubov S.A. Hydrology. M., 2005.

Under the influence of certain geophysical factors. The water mass is characterized by a constant and continuous distribution of physicochemical and biological properties over a long period of time. All components of the water mass form a single complex that can change or move as a whole. Unlike air masses, vertical zonality plays a rather important role for masses.

The main characteristics of water masses:

• water temperature,
• the content of biogenic salts (phosphates, silicates, nitrates),
• content of dissolved gases (oxygen, carbon dioxide).

The characteristics of water masses do not remain constant, they fluctuate seasonally and for many years within certain limits. There are no clear boundaries between the water masses; instead, there are transitional zones of mutual influence. This can be observed most clearly at the boundary between warm and cold sea currents.

The main factors in the formation of water masses are the heat and water balances of the region.

Water masses quite actively interact with the atmosphere. They give it heat and moisture, biogenic and mechanical oxygen, and absorb carbon dioxide from it.

Classification

There are primary and secondary water masses. The former include those whose characteristics are formed under the influence of earth's atmosphere. They are characterized by the greatest amplitude of changes in their properties in a certain volume of the water column. Secondary water masses include those that are formed under the influence of mixing of the primary ones. They are characterized by the greatest homogeneity.

According to depth and physiographic properties, the following types of water masses are distinguished:

• surface:
  • surface (primary) - to depths of 150-200 m,
  • subsurface (primary and secondary) - from 150-200 m to 400-500 m;
• intermediate (primary and secondary) - the middle layer of ocean waters with a thickness of about 1000 m, at depths from 400-500 m to 1000-1500 m, the temperature of which is only a few degrees above the freezing point of water; a permanent boundary between surface and deep waters, which prevents their mixing;
• deep (secondary) - at a depth of 1000-1500 m to 2500-3000 m;
• bottom (secondary) - deeper than 3 km.

Spreading

Types of surface water masses

equatorial

Throughout the year, the equatorial waters are strongly warmed by the sun, which is at its zenith. Layer thickness - 150-300 g. The horizontal speed of movement is from 60-70 to 120-130 cm/sec. Vertical mixing occurs at a speed of 10 -2 10 -3 cm/sec. Water temperature is 27°...+28°C, seasonal variability is small 2°C. The average salinity is from 33-34 to 34-35 ‰, lower than in tropical latitudes, because numerous rivers and heavy daily showers have a rather strong effect, desalinating the upper layer of water. Conditional density 22.0-23.0. Oxygen content 3.0-4.0 ml/l; phosphates - 0.5-1.0 µg-at/l.

tropical

The layer thickness is 300-400 g. The horizontal speed of movement is from 10-20 to 50-70 cm/sec. Vertical mixing occurs at a speed of 10 -3 cm/sec. Water temperature ranges from 18-20 to 25-27°C. The average salinity is 34.5-35.5 ‰. Conditional density 24.0-26.0. Oxygen content 2.0-4.0 ml/l; phosphates - 1.0-2.0 µg-at/l.

Subtropical

The layer thickness is 400-500 g. The horizontal speed of movement is from 20-30 to 80-100 cm/sec. Vertical mixing occurs at a speed of 10 -3 cm/sec. Water temperature ranges from 15-20 to 25-28°C. The average salinity is from 35-36 to 36-37 ‰. Conditional density from 23.0-24.0 to 25.0-26.0. Oxygen content 4.0-5.0 ml/l; phosphates -

Subpolar

The layer thickness is 300-400 g. The horizontal speed of movement is from 10-20 to 30-50 cm/sec. Vertical mixing occurs at a speed of 10 -4 cm/sec. Water temperature ranges from 15-20 to 5-10°C. The average salinity is 34-35 ‰. Conditional density 25.0-27.0. Oxygen content 4.0-6.0 ml/l; phosphates - 0.5-1.5 µg-at/l.

Literature

1. (English) Emery, W. J. and J. Meincke. 1986 Global water masses: summary and review. Oceanologica Acta, 9:-391.
2. (Russian) Agerov V.K. About the main water masses in the hydrosphere, M. - Sverdlovsk, 1944.
3. (Russian) Zubov N. N. Dynamic Oceanology. M. - L., 1947.
4. (Russian) Muromtsev A. M. The main features of the hydrology of the Pacific Ocean, L., 1958.
5. (Russian) Muromtsev A. M. The main features of the hydrology of the Indian Ocean, L., 1959.
6. (Russian) Dobrovolsky A.D. On the determination of water masses // Oceanology, 1961, v. 1, issue 1.
7. (German) Defant A., Dynamische Ozeanographie, B., 1929.
8. (English) Sverdrup H. U., Jonson M. W., Fleming R. H., The oceans, Englewood Cliffs, 1959.

The entire mass of the waters of the World Ocean is conditionally divided into surface and deep. Surface waters - a layer 200–300 m thick - are very heterogeneous in terms of natural properties; they can be called oceanic troposphere. The rest of the water ocean Stratosphere, constituting the main mass of waters, is more homogeneous.

Surface waters - a zone of active thermal and dynamic interaction

ocean and atmosphere. In accordance with zonal climatic changes, they are subdivided into various water masses, primarily according to thermohaline properties. water masses- these are relatively large volumes of water that form in certain zones (foci) of the ocean and have stable physicochemical and biological properties for a long time.

Allocate five types water masses: equatorial, tropical, subtropical, subpolar and polar.

Equatorial water masses(0-5 ° N. w.) form inter-trade countercurrents. They have constantly high temperatures (26-28 ° C), a clearly defined layer of temperature jump at a depth of 20-50 m, reduced density and salinity - 34 - 34.5‰, low oxygen content - 3-4 g / m 3, low full of life forms. The rise of water masses prevails. In the atmosphere above them there is a belt of low pressure and calm.

Tropical water masses(5– 35° N sh. and 0–30°S sh.) are distributed along the equatorial peripheries of subtropical baric maxima; they form trade winds. The temperature in summer reaches +26...+28°C, in winter it drops to +18...+20°C, and it differs near the western and eastern coasts due to currents and coastal stationary upwellings and downwellings. Upwelling(English, upwelling- floating) - the upward movement of water from a depth of 50–100 m, generated by offshore winds near the western coasts of the continents in a band of 10–30 km. Possessing a lower temperature and, in connection with this, a significant saturation with oxygen, deep waters, rich in biogenic and mineral substances, entering the surface illuminated zone, increase the productivity of the water mass. Downwellings- descending flows near the eastern coasts of the continents due to the surge of water; they bring heat and oxygen down. The temperature jump layer is expressed throughout the year, salinity is 35–35.5‰, oxygen content is 2–4 g/m 3 .

Subtropical water masses have the most characteristic and stable properties in the "core" - circular water areas, limited by large rings of currents. The temperature during the year varies from 28 to 15°C, there is a layer of temperature jump. Salinity 36–37‰, oxygen content 4–5 g/m 3 . In the center of the cycles, the waters sink. In warm currents, subtropical water masses penetrate into temperate latitudes up to 50 ° N. sh. and 40–45°S sh. These transformed subtropical water masses here occupy almost the entire water area of ​​the Atlantic, Pacific and Indian oceans. Cooling, subtropical waters give off a huge amount of heat to the atmosphere, especially in winter, playing a very significant role in planetary heat exchange between latitudes. The boundaries of subtropical and tropical waters are very arbitrary, so some oceanologists combine them into one type of tropical waters.

Subpolar– subarctic (50–70° N) and subantarctic (45–60° S) water masses. For them, a variety of characteristics is typical both for the seasons of the year and for the hemispheres. The temperature in summer is 12–15°C, in winter 5–7°C, decreasing towards the poles. sea ​​ice almost never happens, but there are icebergs. The temperature jump layer is expressed only in summer. Salinity decreases from 35 to 33‰ towards the poles. The oxygen content is 4 - 6 g/m 3 , so the waters are rich in life forms. These water masses occupy the north of the Atlantic and the Pacific Ocean, penetrating in cold currents along the eastern coasts of the continents into temperate latitudes. In the southern hemisphere, they form a continuous zone south of all continents. In general, this is the western circulation of air and water masses, a strip of storms.

Polar water masses in the Arctic and around Antarctica, they have a low temperature: in summer about 0 ° C, in winter -1.5 ... -1.7 ° C. Brackish sea and fresh continental ice and their fragments are constant here. There is no temperature jump layer. Salinity 32–33‰. Dissolved in cold waters maximum amount oxygen - 5–7 g / m 3. On the border with subpolar waters, dense cold waters sink, especially in winter.

Each water mass has its own source of formation. When water masses with different properties meet, they form ocean fronts, or convergence zones (lat. converge- I'm going). They usually form at the junction of warm and cold surface currents and are characterized by the sinking of water masses. There are several frontal zones in the World Ocean, but there are four main ones, two each in the northern and southern hemispheres. In temperate latitudes, they are expressed near the eastern coasts of the continents at the boundaries of the subpolar cyclonic and subtropical anticyclonic gyres with their respectively cold and warm currents: near Newfoundland, Hokkaido, the Falkland Islands and New Zealand. In these frontal zones, hydrothermal characteristics (temperature, salinity, density, current velocities, seasonal temperature fluctuations, wind wave sizes, amount of fog, cloudiness, etc.) reach extreme values. To the east, due to the mixing of waters, frontal contrasts are blurred. It is in these zones that frontal cyclones of extratropical latitudes originate. Two frontal zones also exist on both sides of the thermal equator near the western coasts of the continents between relatively cold tropical waters and warm equatorial waters of the trade wind countercurrents. They are also distinguished by high values ​​of hydrometeorological characteristics, high dynamic and biological activity, and intense interaction between the ocean and the atmosphere. These are areas where tropical cyclones originate.

is in the ocean and divergence zones (lat. diuergento- I deviate) - zones of divergence of surface currents and rise of deep waters: near the western coasts of the continents of temperate latitudes and above the thermal equator near the eastern coasts of the continents. Such zones are rich in phyto- and zooplankton, are distinguished by increased biological productivity and are areas of effective fishing.

The oceanic stratosphere is divided by depth into three layers, differing in temperature, illumination and other properties: intermediate, deep and bottom waters. Intermediate waters are located at depths from 300–500 to 1000–1200 m. Their thickness is maximum in polar latitudes and in the central parts of anticyclonic gyres, where water subsidence predominates. Their properties are somewhat different depending on the latitude of distribution. The total transport of these waters is directed from high latitudes to the equator.

Deep and especially near-bottom waters (the thickness of the layer of the latter is 1000–1500 m above the bottom) are distinguished by high uniformity (low temperatures, richness of oxygen) and slow speed of movement in the meridional direction from the polar latitudes to the equator. Especially widespread are Antarctic waters, "sliding" from the continental slope of Antarctica. They not only occupy the entire southern hemisphere, but also reach 10–12°N. sh. in the Pacific Ocean, up to 40 ° N. sh. in the Atlantic and to the Arabian Sea in the Indian Ocean.

From the characteristics of water masses, especially surface ones, and currents, the interaction between the ocean and the atmosphere is clearly visible. The ocean gives the atmosphere the bulk of the heat, converting the radiant energy of the sun into heat. The ocean is a huge distiller, supplying the land with fresh water through the atmosphere. The heat entering the atmosphere from the oceans causes various Atmosphere pressure. The difference in pressure creates wind. It causes excitement and currents that transfer heat to high latitudes or cold to low latitudes, etc. The processes of interaction between the two shells of the Earth - the atmosphere and the oceanosphere - are complex and diverse.

As a result of dynamic processes occurring in the oceanic water column, a more or less mobile water stratification is established in it. This stratification leads to the isolation of the so-called water masses. Water masses are waters characterized by their inherent conservative properties. Moreover, these properties are acquired by water masses in certain areas and retained within the entire space of their distribution.

According to V.N. Stepanov (1974) are distinguished: surface, intermediate, deep and bottom water masses. The main types of water masses can, in turn, be divided into varieties.

Surface water masses are characterized by the fact that they are formed by direct interaction with the atmosphere. As a result of interaction with the atmosphere, these water masses are most susceptible to: mixing by waves, changes in the properties of ocean water (temperature, salinity, and other properties).

The thickness of the surface masses is on average 200-250 m. They are also distinguished by the maximum transfer rate - on average about 15-20 cm/s in the horizontal direction and 10 10-4 - 2 10-4 cm/s in the vertical direction. They are subdivided into equatorial (E), tropical (ST and UT), subarctic (SbAr), subantarctic (SbAn), antarctic (An), and arctic (Ar).

Intermediate water masses stand out in the polar regions with elevated temperatures, in temperate and tropical regions - with low or high salinity. Their upper boundary is the boundary with surface water masses. The lower boundary lies at a depth of 1000 to 2000 m. Intermediate water masses are subdivided into subantarctic (PSbAn), subarctic (PSbAr), North Atlantic (PSAt), North Indian Ocean (PSI), Antarctic (PAn) and Arctic (PAR) masses.

The main part of the intermediate subpolar water masses is formed due to the subsidence of surface waters in the subpolar convergence zones. The transfer of these water masses is directed from the subpolar regions to the equator. In the Atlantic Ocean, the subantarctic intermediate water masses pass beyond the equator and are distributed up to about 20° N, in the Pacific - up to the equator, in the Indian - up to about 10° S. Subarctic intermediate waters in the Pacific also reach the equator. In the Atlantic Ocean, they quickly sink and get lost.

In the northern parts of the Atlantic and Indian Oceans, the intermediate masses have a different origin. They form on the surface in areas of high evaporation. As a result, excessively saline waters are formed. Because of their high density, these salty waters experience a slow sinking. To them are added dense salty waters from the Mediterranean Sea (in the North Atlantic) and from the Red Sea and the Persian and Oman Gulfs (in the Indian Ocean). In the Atlantic Ocean, intermediate waters flow under the surface layer north and south of the latitude of the Strait of Gibraltar. They spread between 20 and 60°N. In the Indian Ocean, these waters spread south and southeast to 5-10°S.

The pattern of intermediate water circulation was revealed by V.A. Burkov and R.P. Bulatov. It is distinguished by an almost complete attenuation of wind circulations in the tropical and equatorial zones and a slight shift of subtropical circulations towards the poles. In this regard, intermediate waters from the polar fronts spread to the tropical and subpolar regions. The same circulation system includes subsurface equatorial countercurrents of the Lomonosov current type.

Deep water masses are formed mainly in high latitudes. Their formation is associated with the mixing of surface and intermediate water masses. They usually form on the shelves. Cooling and, accordingly, acquiring a greater density, these masses gradually slide down the continental slope and spread towards the equator. The lower boundary of deep waters is located at a depth of about 4000 m. The intensity of deep water circulation was studied by V.A. Burkov, R.P. Bulatov and A.D. Shcherbinin. It weakens with depth. In the horizontal movement of these water masses, the main role is played by: southern anticyclonic gyres; circumpolar deep current in the southern hemisphere, which provides the exchange of deep water between the oceans. The horizontal movement speeds are approximately 0.2-0.8 cm/s, and the vertical ones are 1 10-4 to 7 1004 cm/s.

Deep water masses are subdivided into: the circumpolar deep water mass of the Southern Hemisphere (GCP), the North Atlantic (GSAt), the North Pacific Ocean (GTS), the North Indian Ocean (GSI) and the Arctic (GAr). Deep North Atlantic waters are characterized by increased salinity (up to 34.95%) and temperature (up to 3°) and a slightly increased travel speed. The following are involved in their formation: waters of high latitudes, cooled on the polar shelves and sinking with the mixing of surface and intermediate waters, heavy salty waters of the Mediterranean, rather salty waters of the Gulf Stream. Their sinking intensifies as they move to higher latitudes, where they experience gradual cooling.

Circumpolar deep waters are formed exclusively due to the cooling of waters in the Antarctic regions of the World Ocean. The northern deep masses of the Indian and Pacific Oceans are of local origin. In the Indian Ocean due to the runoff of salt water from the Red Sea and the Persian Gulf. In the Pacific Ocean, mainly due to the cooling of waters on the shelf of the Bering Sea.

Bottom water masses are characterized by the lowest temperatures and the highest density. They occupy the rest of the ocean deeper than 4000 m. These water masses are characterized by very slow horizontal movement, mainly in the meridional direction. Bottom water masses are characterized by somewhat larger vertical displacements compared to deep water masses. These values ​​are due to the influx of geothermal heat from the ocean floor. These water masses are formed by lowering the overlying water masses. Among the bottom water masses, the bottom Antarctic waters (PrAn) are the most widespread. These waters are well traced by the lowest temperatures and relatively high oxygen content. The center of their formation is the Antarctic regions of the World Ocean and, in particular, the shelf of Antarctica. In addition, the North Atlantic and North Pacific near-bottom water masses (NrSat and NrST) are distinguished.

Bottom water masses are also in a state of circulation. They are characterized mainly by meridional transport in a northerly direction. In addition, in the northwestern part of the Atlantic, a southward current is clearly expressed, which is fed by the cold waters of the Norwegian-Greenland basin. The speed of movement of the bottom masses slightly increases when approaching the bottom.

Waves and wave movements of the oceans

Chemical composition and salinity of sea water

Almost all known chemical elements are present in sea water:

Chemical elements(by weight)----

Element-Percentage

Oxygen 85.7

Hydrogen 10.8

Calcium 0.04

Potassium 0.0380

Sodium 1.05

Magnesium 0.1350 Carbon 0.0026

Among these substances, a group of elements that determine the salinity of water is distinguished. Salinity is the most important characteristic of water, which determines many physical properties of water: density, freezing rate, sound speed, etc. Its value depends on evaporation, fresh water flow, ice melting, water freezing, ...

In the tropics, salinity is maximum compared to other latitudes. This is due to the fact that evaporation far exceeds precipitation. The minimum salinity is at the equator.

The average salinity of the oceans is about 3.5%. This means that 35 grams of salts (mainly sodium chloride) are dissolved in every liter of sea water. The salinity of water in the oceans is almost universally close to 3.5%, but the water in the seas has an unevenly distributed salinity. The least saline is the water of the Gulf of Finland and the northern part of the Gulf of Bothnia, which are part of the Baltic Sea. The most salty is the water of the Red Sea. Salt lakes such as the Dead Sea can have significantly higher levels of salt.

Waves on water differ in the fundamental mechanism of oscillation (capillary, gravitational, etc.), which leads to different dispersion laws and, as a result, to different behavior of these waves.

The lower part of the wave is called the bottom, the upper part is called the crest. During the movement of the wave, the crest moves forward relative to the base, leaning down, after which, due to its own weight and gravity, the crest falls, the wave breaks, and the level of the wave height becomes equal to zero.

The main elements of the wave:

Length - the shortest distance between two adjacent vertices (ridges/hollows)

Height - the difference between the levels of the top and bottom

Steepness - the ratio of the height of a wave to its length

Wave level - a line dividing the trochoids in half

Period is the time it takes a wave to travel a distance equal to its length.

Frequency - number of oscillations per second

The direction of the wave is measured as well as the direction of the wind ("to the compass")

Water masses - the volume of water, commensurate with the area and depth of the reservoir and having a relative uniformity of physico-chemical characteristics that are formed in specific physiographic conditions. The main factors that form the water masses are the heat and water balances of the area, temperature and salinity.

The characteristics of the Water mass do not remain constant; they are subject to seasonal and long-term fluctuations within certain limits and change in space. As they spread from the formation area, the water masses are transformed under the influence of changes in the conditions of heat and water balances and mix with the surrounding waters.

Vertically: surface - to a depth of 150-200 m;

Subsurface - at a depth of 150-200 m to 400-500 m;

Intermediate - at a depth of 400-500 m to 1000-1500 m,

Deep - at a depth of 1000-1500 m to 2500-3000 m;

Bottom (secondary) - below 3000 m.

Horizontally: equatorial, tropical, subtropical, subpolar and polar.

The boundaries between the water masses are the zones of the fronts of the World Ocean, the zones of division and the zones of transformation, which are traced along the increasing horizontal and vertical gradients of the main indicators.