The Brazil–Falkland Confluence Zone (also called the Brazil–Falklands Confluence Zone or the Brazil–Malvinas Confluence Zone) is a very energetic region of water just off the coast of

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

where the warm poleward flowing

Brazil Current The Brazil Current is a warm water current that flows south along the Brazilian south coast to the mouth of the Río de la Plata. Description This current is caused by diversion of a portion of the Atlantic South Equatorial Current from where ...

and the cold equatorward flowing

Falkland Current The Falkland Current (also called Malvinas Current or Falklands Current) is a cold water current that flows northward along the Atlantic coast of Patagonia as far north as the mouth of the Río de la Plata. This current results from the movement o ...

converge. The region oscillates latitudinally, but in general the region of

confluence In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main stem); o ...

occurs between 35 and 45 degrees south latitude and 50 to 70 degrees west longitude. The confluence of these two currents causes a strong

thermohaline Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective ''thermohaline'' derives from '' thermo-'' referring to tempe ...

to exist and causes numerous high energy

eddies In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid beh ...

to form.Maamaatuaiahutapu, K. et al.(1998)., Transports of the Brazil and Malvinas Currents at their Confluence.

Journal of Marine Research The ''Journal of Marine Research'' is an American journal, first published by Yale University in 1937, that covers peer-reviewed scientific articles and is still published today. The academic journal publishes articles Article often refers to: ...

Vol. 56 Issue 2, p417

Brazil Current

The Brazil Current is a poleward flowing current that carries warm

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

water. The Brazil Current branches off northward from the

South Equatorial Current The South Equatorial Current are ocean currents in the Pacific, Atlantic, and Indian Ocean that flow east-to-west between the equator and about 20 degrees south. In the Pacific and Atlantic Oceans, it extends across the equator to about 5 degr ...

at around 10 degrees South. As it flows poleward it branches off into two pieces at around 22 degrees South. One part flows eastward, and the other portion continues the poleward march flowing along the South American

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

. The poleward directed branch is the current that comes into convergence with the Falklands Current. Typical temperature values for the Brazil Current are between 18 and 28 degrees Celsius, decreasing as it moves poleward. Typical

salinities Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

for the Brazil Current range between 35 and 36psu with some isolated spots as high as 37 psu. The current typically flows in the upper 600 meters of the ocean and its volume transport as it reaches the confluence zone is upwards of 20

Sverdrup In oceanography, the sverdrup (symbol: Sv) is a non- SI metric unit of volumetric flow rate, with equal to . It is equivalent to the SI derived unit cubic hectometer per second (symbol: hm3/s or hm3⋅s−1): 1 Sv is equal to 1 hm3/s. It is used ...

s with speeds over a half a meter per second.

Falkland Current

The

(also called Falklands Current or Malvinas Current) is an equatorward flowing current that carries cold and relatively fresh

subantarctic The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...

water. The Falkland Current is a branch off of the

Antarctic Circumpolar Current The Antarctic Circumpolar Current (ACC) is an ocean current that flows clockwise (as seen from the South Pole) from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feat ...

. It transports between 60 and 90 Sverdrups of water with speeds ranging from a half a meter to a meter per second. Hydrographic data in this area is very scarce and thus various hydrographic variables have a great deal of error. The Falkland Current is not simply a

surface current An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, ...

like the Brazil Current, but extends all the way to the sea floor. Typical temperatures for the current are around 6 °C, with a salinity of 33.5–34.5 psu.

Water masses in confluence zone

There are a total of seven different

water mass An oceanographic water mass is an identifiable body of water with a common formation history which has physical properties distinct from surrounding water. Properties include temperature, salinity, chemical - isotopic ratios, and other physical ...

es in the Brazil–Falkland Confluence Zone. These various water masses help contribute even more to this very complex dynamical confluence zone. Starting at the surface (<800m) where the Brazil Current is carrying Subtropical Surface Water and the Falkland Current is carrying Subantarctic Surface Water, after these two surfaces collide they mix some, but in general they develop strong thermohaline fronts due to the strong difference in

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

and salinity. Below the surface from about 800 meters to 1500 meters there is Antarctic Intermediate Water that is flowing equatorward. At the very bottom of the Brazil–Falkland Confluence Zone there is equatorward flowing

Weddell Sea The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha ...

Deep Water. Between the Antarctic Intermediate Water and the Weddel Sea Deep Water there are three different water masses flowing poleward:

North Atlantic Deep Water North Atlantic Deep Water (NADW) is a deep water mass formed in the North Atlantic Ocean. Thermohaline circulation (properly described as meridional overturning circulation) of the world's oceans involves the flow of warm surface waters from the ...

, Lower Circumpolar Deep Water, and Upper Circumpolar Deep Water.

Surface flow and thermohaline gradients in the confluence zone

The surface flow in the Brazil–Falkland Confluence Zone is still not quite well understood, but more recently

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

s have been able to give us a better idea of what this flow looks like. After the Brazil Current collides with the Falkland Current at around 38 degrees South, it branches off into two different paths. The first path gets redirected back equatorward and actually creates a large

anticyclonic An anticyclone is a weather phenomenon defined as a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere as viewed from abov ...

eddy with the original Brazil Current. The second path of the Brazil Current, which is much stronger than the aforementioned redirected path, is deflected about 45 degrees east of its original tract poleward. The surface flow for the Falkland Current after the collision with the Brazil Current is much simpler than that of the Brazil Current. Once the Falkland Current collides with the Brazil Current at the Brazil–Falkland Confluence Zone the Falkland Current gets redirected poleward. It will continue to follow this poleward tract till about 50 degrees South latitude where it will once again be picked back up by the Antarctic Circumpolar Current and head East. The temperature and salinity gradients that are generated by the Brazil–Falkland Confluence Zone are amazing. The southeast deflected Brazil Current flows just east of the redirected Falkland current at around 57.5W and between 40 and 45S (See fig. 4). In this region sea surface temperature gradients can be as high as 1 degree C per kilometer. Salinity gradients are also extraordinarily high in this region. The

meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex bank ...

s, eddies, and filaments created in this confluence zone are extraordinary. The eddies exhibit strong rotational velocities and are extremely energetic. At any given time there could be 8 or 9 distinct

mesoscale eddies In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid b ...

with many other

microscale The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Un ...

eddies existing at the same time. There is a lot of research going into the study of these high energy turbulent mixing areas, but it is still far too early to understand these mesoscale processes in depth.

The BMC, Local Climate, and Global Climate

The presence of both currents, which have a stark contrast in properties, is the characteristic feature of the region. The northward flow of the cold Falkland and the southward flow of the Brazil current has an influence on both local and global climate. They impact local biology because the Falkland is nutrient rich and brings needed nutrients into the basin, causing chlorophyll blooms and supporting plant life that in turn attracts fish to feed on. Therefore, the BMC has an impact on commercial fishing to the point where fishermen track where the collision occurs throughout the year. From a global perspective, the BMC is important because the cold Falkland warms as it encounters the subtropical climate which leads to the outgassing of (warmer water cannot contain as much gas), and the warm Brazil current cools as it encounters the same climate which has the opposite effect - cooler water can contain more gas so the cooling of the Brazil increases the uptake of . The presence of the biology mentioned above also sequesters , allowing more to be taken up by the ocean. The photosynthetic utilization of by the plants, and the regions strong wind speeds leads the region to have increase flux as well. All of this together makes the BMC a large carbon sink for global atmospheric . Some estimates of air-sea flux actually indicate that the BMC is the region of the strongest in the southern hemisphere.

Current research

Current research is focusing in on trying to better observe the Brazil–Falkland Confluence Zone so the dynamics of this system can be better explained. Right now there only exists images of these small scale dynamical process (e.g. eddies), however, numerical interpretation of these eddies are still very much in the beginning stages of our understanding. The other major area of research is focusing in on the biological productivity in this region. This confluence zone is such a "hot spot" for primary production because the Falkland Current supplies a lot of

nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

s while the Brazil Current supplies warm ocean temperatures. Intense vertical mixing in these zones create a very fertile area for the production of biological species. This zone is looked at as a major atmospheric

carbon sink A carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide () from the atmosphere. Globally, the two most important carbon si ...

due to the amount of primary production that takes place here which is vitally important in our changing climate.Chiessi et al. (2007). Signature of the Brazil-Malvinas Confluence (Argentina Basin) in the isotopic composition of planktonic foraminifera from surface sediments. Marine Micropaleonotology 64. pp. 52-66. Figure 5 shows

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

-a concentration in this zone.

References

{{DEFAULTSORT:Brazil-Falkland Confluence Currents of the Atlantic Ocean