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98-650: The Mindanao Current flows towards the equator and is most intense near the surface, reaching maximum speeds of 1.3 {\displaystyle 1.3} m s − 1 {\displaystyle ms^{-1}} . It can be observed until depths of 1000 {\displaystyle 1000} m {\displaystyle m} near the Philippine coast and extends until 350 {\displaystyle 350} k m {\displaystyle km} offshore. The MC transports climatic signals and in doing so, influences

196-588: A complex mixture of many different elements from different sources (not all from dissolved salts) in different molecular forms. The chemical properties of some of these forms depend on temperature and pressure. Many of these forms are difficult to measure with high accuracy, and in any case complete chemical analysis is not practical when analyzing multiple samples. Different practical definitions of salinity result from different attempts to account for these problems, to different levels of precision, while still remaining reasonably easy to use. For practical reasons salinity

294-556: A cooler West Pacific and a warmer East Pacific, leading to a shift of cloudiness and rainfall towards the East Pacific. This situation is called El Niño. The opposite occurs if trade winds are stronger than average, leading to a warmer West Pacific and a cooler East Pacific. This situation is called La Niña and is associated with increased cloudiness and rainfall over the West Pacific. The close relationship between ocean temperatures and

392-581: A decrease in the strength of the Pacific trade winds , and a reduction in rainfall over eastern and northern Australia. La Niña episodes are defined as sustained cooling of the central and eastern tropical Pacific Ocean, thus resulting in an increase in the strength of the Pacific trade winds , and the opposite effects in Australia when compared to El Niño. Although the Southern Oscillation Index has

490-490: A few percent (%). Physical oceanographers working in the abyssal ocean , however, are often concerned with precision and intercomparability of measurements by different researchers, at different times, to almost five significant digits . A bottled seawater product known as IAPSO Standard Seawater is used by oceanographers to standardize their measurements with enough precision to meet this requirement. Measurement and definition difficulties arise because natural waters contain

588-485: A larger EP ENSO occurrence, or even displaying opposite conditions from the observed ones in the other Niño regions when accompanied by Modoki variations. ENSO Costero events usually present more localized effects, with warm phases leading to increased rainfall over the coast of Ecuador, northern Peru and the Amazon rainforest , and increased temperatures over the northern Chilean coast, and cold phases leading to droughts on

686-533: A long station record going back to the 1800s, its reliability is limited due to the latitudes of both Darwin and Tahiti being well south of the Equator, so that the surface air pressure at both locations is less directly related to ENSO. To overcome this effect, a new index was created, named the Equatorial Southern Oscillation Index (EQSOI). To generate this index, two new regions, centered on

784-456: A measured density. Marine waters are those of the ocean, another term for which is euhaline seas . The salinity of euhaline seas is 30 to 35 ‰. Brackish seas or waters have salinity in the range of 0.5 to 29 ‰ and metahaline seas from 36 to 40 ‰. These waters are all regarded as thalassic because their salinity is derived from the ocean and defined as homoiohaline if salinity does not vary much over time (essentially constant). The table on

882-411: A negative SSH anomaly (lowered sea level) via contraction. The El Niño–Southern Oscillation is a single climate phenomenon that quasi-periodically fluctuates between three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases which require certain changes to take place in both the ocean and the atmosphere before an event is declared. The cool phase of ENSO is La Niña, with SST in

980-517: A quarter of the planet, and particularly in the form of temperature at the ocean surface, can have a significant effect on weather across the entire planet. Tropical instability waves visible on sea surface temperature maps, showing a tongue of colder water, are often present during neutral or La Niña conditions. La Niña is a complex weather pattern that occurs every few years, often persisting for longer than five months. El Niño and La Niña can be indicators of weather changes across

1078-469: A result can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term surface cooling. Therefore, the relative frequency of El Niño compared to La Niña events can affect global temperature trends on timescales of around ten years. The countries most affected by ENSO are developing countries that are bordering

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1176-425: A secondary peak in sea surface temperature across the far eastern equatorial Pacific Ocean sometimes follows the initial peak. An especially strong Walker circulation causes La Niña, which is considered to be the cold oceanic and positive atmospheric phase of the broader El Niño–Southern Oscillation (ENSO) weather phenomenon, as well as the opposite of El Niño weather pattern, where sea surface temperature across

1274-457: A wide range of salinities is euryhaline . Salts are expensive to remove from water, and salt content is an important factor in water use, factoring into potability and suitability for irrigation . Increases in salinity have been observed in lakes and rivers in the United States, due to common road salt and other salt de-icers in runoff. The degree of salinity in oceans is a driver of

1372-422: Is a global climate phenomenon that emerges from variations in winds and sea surface temperatures over the tropical Pacific Ocean . Those variations have an irregular pattern but do have some semblance of cycles. The occurrence of ENSO is not predictable. It affects the climate of much of the tropics and subtropics , and has links ( teleconnections ) to higher-latitude regions of the world. The warming phase of

1470-583: Is an oscillation in surface air pressure between the tropical eastern and the western Pacific Ocean waters. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI). The SOI is computed from fluctuations in the surface air pressure difference between Tahiti (in the Pacific) and Darwin, Australia (on the Indian Ocean). El Niño episodes have negative SOI, meaning there

1568-456: Is characterized by a salinity maximum of 35 {\displaystyle 35} p s u {\displaystyle psu} or Practical Salinity Units which is relatively high. As the water mass is advected southward by the MC, it evolves: the salinity maximum decays by 0.1 {\displaystyle 0.1} p s u {\displaystyle psu} along

1666-405: Is known as Ekman transport . Colder water from deeper in the ocean rises along the continental margin to replace the near-surface water. This process cools the East Pacific because the thermocline is closer to the ocean surface, leaving relatively little separation between the deeper cold water and the ocean surface. Additionally, the northward-flowing Humboldt Current carries colder water from

1764-520: Is longer, it is classified as an El Niño "episode". It is thought that there have been at least 30 El Niño events between 1900 and 2024, with the 1982–83 , 1997–98 and 2014–16 events among the strongest on record. Since 2000, El Niño events have been observed in 2002–03, 2004–05, 2006–07, 2009–10, 2014–16 , 2018–19, and 2023–24 . Major ENSO events were recorded in the years 1790–93, 1828, 1876–78, 1891, 1925–26, 1972–73, 1982–83, 1997–98, 2014–16, and 2023–24. During strong El Niño episodes,

1862-553: Is lower pressure over Tahiti and higher pressure in Darwin. La Niña episodes on the other hand have positive SOI, meaning there is higher pressure in Tahiti and lower in Darwin. Low atmospheric pressure tends to occur over warm water and high pressure occurs over cold water, in part because of deep convection over the warm water. El Niño episodes are defined as sustained warming of the central and eastern tropical Pacific Ocean, thus resulting in

1960-520: Is pulled in to replace the sinking water, which in turn eventually becomes cold and salty enough to sink. Salinity distribution contributes to shape the oceanic circulation. Limnologists and chemists often define salinity in terms of mass of salt per unit volume, expressed in units of mg/L or g/L. It is implied, although often not stated, that this value applies accurately only at some reference temperature because solution volume varies with temperature. Values presented in this way are typically accurate to

2058-651: Is referred to as brine . Salinity is an ecological factor of considerable importance, influencing the types of organisms that live in a body of water. As well, salinity influences the kinds of plants that will grow either in a water body, or on land fed by a water (or by a groundwater ). A plant adapted to saline conditions is called a halophyte . A halophyte which is tolerant to residual sodium carbonate salinity are called glasswort or saltwort or barilla plants. Organisms (mostly bacteria) that can live in very salty conditions are classified as extremophiles , or halophiles specifically. An organism that can withstand

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2156-409: Is relatively shallow while towards 20°N, it deepens significantly (in the order of 100 {\displaystyle 100} m {\displaystyle m} ). As a consequence, the bifurcation location is northward with increasing depth, i.e., at the shallowest layer ( 0 − 100 {\displaystyle 0-100} m {\displaystyle m} ),

2254-466: Is sometimes referred to as chlorinity. Operationally, dissolved matter is defined as that which can pass through a very fine filter (historically a filter with a pore size of 0.45 μm, but later usually 0.2 μm). Salinity can be expressed in the form of a mass fraction , i.e. the mass of the dissolved material in a unit mass of solution. Seawater typically has a mass salinity of around 35 g/kg, although lower values are typical near coasts where rivers enter

2352-511: 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 to ‰). Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure , governs physical characteristics like

2450-406: Is typically around 0.5 m (1.5 ft) higher than near Peru because of the buildup of water in the West Pacific. The thermocline , or the transitional zone between the warmer waters near the ocean surface and the cooler waters of the deep ocean , is pushed downwards in the West Pacific due to this water accumulation. The total weight of a column of ocean water is almost the same in

2548-470: Is usually related to the sum of masses of a subset of these dissolved chemical constituents (so-called solution salinity ), rather than to the unknown mass of salts that gave rise to this composition (an exception is when artificial seawater is created). For many purposes this sum can be limited to a set of eight major ions in natural waters, although for seawater at highest precision an additional seven minor ions are also included. The major ions dominate

2646-518: The International Date Line and 120°W ), including the area off the west coast of South America , as upwelling of cold water occurs less or not at all offshore. This warming causes a shift in the atmospheric circulation, leading to higher air pressure in the western Pacific and lower in the eastern Pacific, with rainfall reducing over Indonesia, India and northern Australia, while rainfall and tropical cyclone formation increases over

2744-578: The Southern Ocean to the tropics in the East Pacific . The combination of the Humboldt Current and upwelling maintains an area of cooler ocean waters off the coast of Peru. The West Pacific lacks a cold ocean current and has less upwelling as the trade winds are usually weaker than in the East Pacific, allowing the West Pacific to reach warmer temperatures. These warmer waters provide energy for

2842-529: The density and heat capacity of the water. A contour line of constant salinity is called an isohaline , or sometimes isohale . Salinity in rivers, lakes, and the ocean is conceptually simple, but technically challenging to define and measure precisely. Conceptually the salinity is the quantity of dissolved salt content of the water. Salts are compounds like sodium chloride , magnesium sulfate , potassium nitrate , and sodium bicarbonate which dissolve into ions. The concentration of dissolved chloride ions

2940-564: The hydrography is such that a possible cause of reduced circulation is the production of stratified oceans. In such cases, it is more difficult to subduct water through the thermohaline circulation. Not only is salinity a driver of ocean circulation, but changes in ocean circulation also affect salinity, particularly in the subpolar North Atlantic where from 1990 to 2010 increased contributions of Greenland meltwater were counteracted by increased northward transport of salty Atlantic waters. However, North Atlantic waters have become fresher since

3038-474: The upward movement of air . As a result, the warm West Pacific has on average more cloudiness and rainfall than the cool East Pacific. ENSO describes a quasi-periodic change of both oceanic and atmospheric conditions over the tropical Pacific Ocean. These changes affect weather patterns across much of the Earth. The tropical Pacific is said to be in one of three states of ENSO (also called "phases") depending on

Mindanao Current - Misplaced Pages Continue

3136-413: The world's ocean circulation , where density changes due to both salinity changes and temperature changes at the surface of the ocean produce changes in buoyancy, which cause the sinking and rising of water masses. Changes in the salinity of the oceans are thought to contribute to global changes in carbon dioxide as more saline waters are less soluble to carbon dioxide. In addition, during glacial periods,

3234-408: The 1980s. Titration with silver nitrate could be used to determine the concentration of halide ions (mainly chlorine and bromine ) to give a chlorinity . The chlorinity was then multiplied by a factor to account for all other constituents. The resulting 'Knudsen salinities' are expressed in units of parts per thousand (ppt or ‰ ). The use of electrical conductivity measurements to estimate

3332-620: The Bjerknes feedback naturally triggers negative feedbacks that end and reverse the abnormal state of the tropical Pacific. This perspective implies that the processes that lead to El Niño and La Niña also eventually bring about their end, making ENSO a self-sustaining process. Other theories view the state of ENSO as being changed by irregular and external phenomena such as the Madden–Julian oscillation , tropical instability waves , and westerly wind bursts . The three phases of ENSO relate to

3430-474: The Coastal Niño Index (ICEN), strong El Niño Costero events include 1957, 1982–83, 1997–98 and 2015–16, and La Niña Costera ones include 1950, 1954–56, 1962, 1964, 1966, 1967–68, 1970–71, 1975–76 and 2013. Currently, each country has a different threshold for what constitutes an El Niño event, which is tailored to their specific interests, for example: In climate change science, ENSO is known as one of

3528-535: The ENSO trend, the amplitude of the ENSO variability in the observed data still increases, by as much as 60% in the last 50 years. A study published in 2023 by CSIRO researchers found that climate change may have increased by two times the likelihood of strong El Niño events and nine times the likelihood of strong La Niña events. The study stated it found a consensus between different models and experiments. Salinity Salinity ( / s ə ˈ l ɪ n ɪ t i / )

3626-603: The EP and CP types, and some scientists argue that ENSO exists as a continuum, often with hybrid types. The effects of the CP ENSO are different from those of the EP ENSO. The El Niño Modoki is associated with more hurricanes more frequently making landfall in the Atlantic. La Niña Modoki leads to a rainfall increase over northwestern Australia and northern Murray–Darling basin , rather than over

3724-492: The El Niño state. This process is known as Bjerknes feedback . Although these associated changes in the ocean and atmosphere often occur together, the state of the atmosphere may resemble a different ENSO phase than the state of the ocean or vice versa. Because their states are closely linked, the variations of ENSO may arise from changes in both the ocean and atmosphere and not necessarily from an initial change of exclusively one or

3822-491: The El Niños of 2006-07 and 2014-16 were also Central Pacific El Niños. Recent years when La Niña Modoki events occurred include 1973–1974, 1975–1976, 1983–1984, 1988–1989, 1998–1999, 2000–2001, 2008–2009, 2010–2011, and 2016–2017. The recent discovery of ENSO Modoki has some scientists believing it to be linked to global warming. However, comprehensive satellite data go back only to 1979. More research must be done to find

3920-541: The Equator, were defined. The western region is located over Indonesia and the eastern one over the equatorial Pacific, close to the South American coast. However, data on EQSOI goes back only to 1949. Sea surface height (SSH) changes up or down by several centimeters in Pacific equatorial region with the ESNO: El Niño causes a positive SSH anomaly (raised sea level) because of thermal expansion while La Niña causes

4018-559: The MC are controlled by large-scale upper ocean circulation. The variations are often explained by local wind forcing of the western Pacific, both by local winds and winds in the Pacific’s interior which cause westward propagating Rossby waves . Under the influence of climate change, models predict that western boundary currents will be affected in different ways. For the Mindanao Current in particular, numerous simulations have agreed that

Mindanao Current - Misplaced Pages Continue

4116-403: The MC will be shallower. Climate affects the circulation of the western Pacific and on the yearly timescale, ENSO is a major driver. The MC is stronger in the developing stages of the El Niño and weaker during the decaying stage, although with a lot of uncertainty. These variations are probably due to the wind, but the specific mechanism varies with latitude. Profiles of the water column show that

4214-581: The North Pacific and formed at the Philippine Sea by the bifurcation of the NEC. The jet transports approximately 13 − 39 {\displaystyle 13-39} Sv (where 1 {\displaystyle 1} S v = 10 6 m 3 s − 1 {\displaystyle Sv=10^{6}m^{3}s^{-1}} ) to the equator. It flows alongside

4312-473: The Pacific Ocean and are dependent on agriculture and fishing. In climate change science, ENSO is known as one of the internal climate variability phenomena. Future trends in ENSO due to climate change are uncertain, although climate change exacerbates the effects of droughts and floods. The IPCC Sixth Assessment Report summarized the scientific knowledge in 2021 for the future of ENSO as follows: "In

4410-520: The Philippine coast. Once it reaches a latitude of 6°N, it becomes indiscernible. In contrast, the waters of the MUC transport Antarctic Intermediate Water which originates from the south Pacific. It is characterized by a salinity greater than 34.5 {\displaystyle 34.5} p s u {\displaystyle psu} and usually contains more oxygen than the NPIW. The MC originates from

4508-453: The Walker circulation, which was named after Gilbert Walker who discovered the Southern Oscillation during the early twentieth century. The Walker circulation is an east-west overturning circulation in the vicinity of the equator in the Pacific. Upward air is associated with high sea temperatures, convection and rainfall, while the downward branch occurs over cooler sea surface temperatures in

4606-454: The West Pacific northeast of Australia averages around 28–30 °C (82–86 °F). SSTs in the East Pacific off the western coast of South America are closer to 20 °C (68 °F). Strong trade winds near the equator push water away from the East Pacific and towards the West Pacific. This water is slowly warmed by the Sun as it moves west along the equator. The ocean surface near Indonesia

4704-460: The West Pacific to a depth of about 30 m (90 ft) in the East Pacific. Cooler deep ocean water takes the place of the outgoing surface waters in the East Pacific, rising to the ocean surface in a process called upwelling . Along the western coast of South America, water near the ocean surface is pushed westward due to the combination of the trade winds and the Coriolis effect . This process

4802-429: The asymmetric nature of the warm and cold phases of ENSO, some studies could not identify similar variations for La Niña, both in observations and in the climate models, but some sources could identify variations on La Niña with cooler waters on central Pacific and average or warmer water temperatures on both eastern and western Pacific, also showing eastern Pacific Ocean currents going to the opposite direction compared to

4900-436: The atmospheric and oceanic conditions. When the tropical Pacific roughly reflects the average conditions, the state of ENSO is said to be in the neutral phase. However, the tropical Pacific experiences occasional shifts away from these average conditions. If trade winds are weaker than average, the effect of upwelling in the East Pacific and the flow of warmer ocean surface waters towards the West Pacific lessen. This results in

4998-454: The atmospheric changes alter the sea temperatures that in turn alter the atmospheric winds in a positive feedback. Weaker easterly trade winds result in a surge of warm surface waters to the east and reduced ocean upwelling on the equator . In turn, this leads to warmer sea surface temperatures (called El Niño), a weaker Walker circulation (an east-west overturning circulation in the atmosphere) and even weaker trade winds. Ultimately

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5096-460: The bifurcation occurs at ~12°N; at 100 − 300 {\displaystyle 100-300} m {\displaystyle m} , it occurs at ~13°N; at depths of 300 − 600 {\displaystyle 300-600} m {\displaystyle m} , it occurs at ~ 15°N. Thus, the origin of the Mindanao Current is more northern with depth. Observations from December 2010 to August 2014 show that

5194-455: The central and eastern Pacific and lower pressure through much of the rest of the tropics and subtropics. The two phenomena last a year or so each and typically occur every two to seven years with varying intensity, with neutral periods of lower intensity interspersed. El Niño events can be more intense but La Niña events may repeat and last longer. A key mechanism of ENSO is the Bjerknes feedback (named after Jacob Bjerknes in 1969) in which

5292-417: The composition of seawater. They can also be determined by making direct density measurements. A sample of seawater from most locations with a chlorinity of 19.37 ppt will have a Knudsen salinity of 35.00 ppt, a PSS-78 practical salinity of about 35.0, and a TEOS-10 absolute salinity of about 35.2 g/kg. The electrical conductivity of this water at a temperature of 15 °C is 42.9 mS/cm. On

5390-613: The contours of the Philippine coast, approximately following the mean dynamic bathymetry based on underwater glider observations. The MC feeds the equatorial currents, including the North Equatorial Countercurrent and the Indonesian Throughflow which transports water from the Pacific to the Indian Ocean . Thus, the Mindanao Current serves a role in the global overturning circulation . It often interacts with

5488-591: The correlation and study past El Niño episodes. More generally, there is no scientific consensus on how/if climate change might affect ENSO. There is also a scientific debate on the very existence of this "new" ENSO. A number of studies dispute the reality of this statistical distinction or its increasing occurrence, or both, either arguing the reliable record is too short to detect such a distinction, finding no distinction or trend using other statistical approaches, or that other types should be distinguished, such as standard and extreme ENSO. Likewise, following

5586-487: The current will decrease in strength. It is projected to decrease by a magnitude of 2.3 − 5.6 {\displaystyle 2.3-5.6} S v {\displaystyle Sv} along with the Indonesian Throughflow which it supplies. Although the total transport will probably weaken, most of the weakening is subsurface and it will intensify above 100 m south of 7°S, which suggests that

5684-543: The currents in traditional La Niñas. Coined by the Peruvian Comité Multisectorial Encargado del Estudio Nacional del Fenómeno El Niño (ENFEN), ENSO Costero, or ENSO Oriental, is the name given to the phenomenon where the sea-surface temperature anomalies are mostly focused on the South American coastline, especially from Peru and Ecuador. Studies point many factors that can lead to its occurrence, sometimes accompanying, or being accompanied, by

5782-461: The east. During El Niño, as the sea surface temperatures change so does the Walker Circulation. Warming in the eastern tropical Pacific weakens or reverses the downward branch, while cooler conditions in the west lead to less rain and downward air, so the Walker Circulation first weakens and may reverse.   The Southern Oscillation is the atmospheric component of ENSO. This component

5880-614: The eastern Pacific below average, and air pressure high in the eastern Pacific and low in the western Pacific. The ENSO cycle, including both El Niño and La Niña, causes global changes in temperature and rainfall. If the temperature variation from climatology is within 0.5 °C (0.9 °F), ENSO conditions are described as neutral. Neutral conditions are the transition between warm and cold phases of ENSO. Sea surface temperatures (by definition), tropical precipitation, and wind patterns are near average conditions during this phase. Close to half of all years are within neutral periods. During

5978-479: The eastern Pacific. However, in the 1990s and 2000s, variations of ENSO conditions were observed, in which the usual place of the temperature anomaly (Niño 1 and 2) is not affected, but an anomaly also arises in the central Pacific (Niño 3.4). The phenomenon is called Central Pacific (CP) ENSO, "dateline" ENSO (because the anomaly arises near the dateline ), or ENSO "Modoki" (Modoki is Japanese for "similar, but different"). There are variations of ENSO additional to

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6076-404: The eastern equatorial part of the central Pacific Ocean will be lower than normal by 3–5 °C (5.4–9 °F). The phenomenon occurs as strong winds blow warm water at the ocean's surface away from South America, across the Pacific Ocean towards Indonesia. As this warm water moves west, cold water from the deep sea rises to the surface near South America. The movement of so much heat across

6174-567: The eastern portion of the country as in a conventional EP La Niña. Also, La Niña Modoki increases the frequency of cyclonic storms over Bay of Bengal , but decreases the occurrence of severe storms in the Indian Ocean overall. The first recorded El Niño that originated in the central Pacific and moved toward the east was in 1986. Recent Central Pacific El Niños happened in 1986–87, 1991–92, 1994–95, 2002–03, 2004–05 and 2009–10. Furthermore, there were "Modoki" events in 1957–59, 1963–64, 1965–66, 1968–70, 1977–78 and 1979–80. Some sources say that

6272-718: The following years: Transitional phases at the onset or departure of El Niño or La Niña can also be important factors on global weather by affecting teleconnections . Significant episodes, known as Trans-Niño, are measured by the Trans-Niño index (TNI). Examples of affected short-time climate in North America include precipitation in the Northwest US and intense tornado activity in the contiguous US. The first ENSO pattern to be recognised, called Eastern Pacific (EP) ENSO, to distinguish if from others, involves temperature anomalies in

6370-491: The form of silicic acid , which usually appears as a neutral molecule in the pH range of most natural waters, may also be included for some purposes (e.g., when salinity/density relationships are being investigated). The term 'salinity' is, for oceanographers, usually associated with one of a set of specific measurement techniques. As the dominant techniques evolve, so do different descriptions of salinity. Salinities were largely measured using titration -based techniques before

6468-411: The global scale, it is extremely likely that human-caused climate change has contributed to observed surface and subsurface salinity changes since the 1950s, and projections of surface salinity changes throughout the 21st century indicate that fresh ocean regions will continue to get fresher and salty regions will continue to get saltier. Salinity is serving as a tracer of different masses. Surface water

6566-409: The globe. Atlantic and Pacific hurricanes can have different characteristics due to lower or higher wind shear and cooler or warmer sea surface temperatures. La Niña events have been observed for hundreds of years, and occurred on a regular basis during the early parts of both the 17th and 19th centuries. Since the start of the 20th century, La Niña events have occurred during

6664-421: The inorganic composition of most (but by no means all) natural waters. Exceptions include some pit lakes and waters from some hydrothermal springs . The concentrations of dissolved gases like oxygen and nitrogen are not usually included in descriptions of salinity. However, carbon dioxide gas, which when dissolved is partially converted into carbonates and bicarbonates , is often included. Silicon in

6762-471: The internal climate variability phenomena. The other two main ones are Pacific decadal oscillation and Atlantic multidecadal oscillation . La Niña impacts the global climate and disrupts normal weather patterns, which can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term cooling. Therefore,

6860-412: The ionic content of seawater led to the development of the scale called the practical salinity scale 1978 (PSS-78). Salinities measured using PSS-78 do not have units. The suffix psu or PSU (denoting practical salinity unit ) is sometimes added to PSS-78 measurement values. The addition of PSU as a unit after the value is "formally incorrect and strongly discouraged". In 2010 a new standard for

6958-427: The last several decades, the number of El Niño events increased, and the number of La Niña events decreased, although observation of ENSO for much longer is needed to detect robust changes. Studies of historical data show the recent El Niño variation is most likely linked to global warming. For example, some results, even after subtracting the positive influence of decadal variation, are shown to be possibly present in

7056-528: The long term, it is very likely that the precipitation variance related to El Niño–Southern Oscillation will increase". The scientific consensus is also that "it is very likely that rainfall variability related to changes in the strength and spatial extent of ENSO teleconnections will lead to significant changes at regional scale". The El Niño–Southern Oscillation is a single climate phenomenon that periodically fluctuates between three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases in

7154-409: The measured conductivity at 5 °C might only be in the range of 50–80 μS/cm. Direct density measurements are also used to estimate salinities, particularly in highly saline lakes . Sometimes density at a specific temperature is used as a proxy for salinity. At other times an empirical salinity/density relationship developed for a particular body of water is used to estimate the salinity of samples from

7252-473: The nearby Mindanao Eddy which is a semi-permanent cyclonic recirculation to the east. Beneath the Mindanao Current is an even less studied undercurrent, the Mindanao Undercurrent (MUC), which is deeper than 400 {\displaystyle 400} m {\displaystyle m} and lies offshore of the MC. Both the MC and its undercurrent are pathways for the exchange of water in

7350-629: The neutral ENSO phase, other climate anomalies/patterns such as the sign of the North Atlantic Oscillation or the Pacific–North American teleconnection pattern exert more influence. El Niño conditions are established when the Walker circulation weakens or reverses and the Hadley circulation strengthens, leading to the development of a band of warm ocean water in the central and east-central equatorial Pacific (approximately between

7448-400: The observed phenomenon of more frequent and stronger El Niño events occurs only in the initial phase of the global warming, and then (e.g., after the lower layers of the ocean get warmer, as well), El Niño will become weaker. It may also be that the stabilizing and destabilizing forces influencing the phenomenon will eventually compensate for each other. The consequences of ENSO in terms of

7546-422: The ocean. Rivers and lakes can have a wide range of salinities, from less than 0.01 g/kg to a few g/kg, although there are many places where higher salinities are found. The Dead Sea has a salinity of more than 200 g/kg. Precipitation typically has a TDS of 20 mg/kg or less. Whatever pore size is used in the definition, the resulting salinity value of a given sample of natural water will not vary by more than

7644-491: The order of 1%. Limnologists also use electrical conductivity , or "reference conductivity", as a proxy for salinity. This measurement may be corrected for temperature effects, and is usually expressed in units of μS/cm . A river or lake water with a salinity of around 70 mg/L will typically have a specific conductivity at 25 °C of between 80 and 130 μS/cm. The actual ratio depends on the ions present. The actual conductivity usually changes by about 2% per degree Celsius, so

7742-636: The oscillation which are deemed to occur when specific ocean and atmospheric conditions are reached or exceeded. An early recorded mention of the term "El Niño" ("The Boy" in Spanish) to refer to climate occurred in 1892, when Captain Camilo Carrillo told the geographical society congress in Lima that Peruvian sailors named the warm south-flowing current "El Niño" because it was most noticeable around Christmas. Although pre-Columbian societies were certainly aware of

7840-415: The other. Conceptual models explaining how ENSO operates generally accept the Bjerknes feedback hypothesis. However, ENSO would perpetually remain in one phase if Bjerknes feedback were the only process occurring. Several theories have been proposed to explain how ENSO can change from one state to the next, despite the positive feedback. These explanations broadly fall under two categories. In one view,

7938-417: The peruvian coast, and increased rainfall and decreased temperatures on its mountainous and jungle regions. Because they don't influence the global climate as much as the other types, these events present lesser and weaker correlations to other significant ENSO features, neither always being triggered by Kelvin waves , nor always being accompanied by proportional Southern Oscillation responses. According to

8036-483: The phenomenon, the indigenous names for it have been lost to history. The capitalized term El Niño refers to the Christ Child , Jesus , because periodic warming in the Pacific near South America is usually noticed around Christmas . Originally, the term El Niño applied to an annual weak warm ocean current that ran southwards along the coast of Peru and Ecuador at about Christmas time. However, over time

8134-598: The properties of seawater called the thermodynamic equation of seawater 2010 ( TEOS-10 ) was introduced, advocating absolute salinity as a replacement for practical salinity, and conservative temperature as a replacement for potential temperature . This standard includes a new scale called the reference composition salinity scale . Absolute salinities on this scale are expressed as a mass fraction, in grams per kilogram of solution. Salinities on this scale are determined by combining electrical conductivity measurements with other information that can account for regional changes in

8232-473: The regional climate and the El Niño-Southern Oscillation (ENSO). Overall, the Mindanao Current is critical in the circulation within the whole Pacific basin. However, in comparison with other boundary currents in the North Pacific, the Mindanao Current has received limited attention and therefore little is known about it. The Mindanao Current is a low-latitude western boundary current located in

8330-406: The relative frequency of El Niño compared to La Niña events can affect global temperature trends on decadal timescales. There is no sign that there are actual changes in the ENSO physical phenomenon due to climate change. Climate models do not simulate ENSO well enough to make reliable predictions. Future trends in ENSO are uncertain as different models make different predictions. It may be that

8428-650: The right, modified from Por (1972), follows the "Venice system" (1959). In contrast to homoiohaline environments are certain poikilohaline environments (which may also be thalassic ) in which the salinity variation is biologically significant. Poikilohaline water salinities may range anywhere from 0.5 to greater than 300 ‰. The important characteristic is that these waters tend to vary in salinity over some biologically meaningful range seasonally or on some other roughly comparable time scale. Put simply, these are bodies of water with quite variable salinity. Highly saline water, from which salts crystallize (or are about to),

8526-472: The sea surface temperature is known as " El Niño " and the cooling phase as " La Niña ". The Southern Oscillation is the accompanying atmospheric oscillation , which is coupled with the sea temperature change. El Niño is associated with higher than normal air sea level pressure over Indonesia, Australia and across the Indian Ocean to the Atlantic . La Niña has roughly the reverse pattern: high pressure over

8624-540: The southern branch of the NEC bifurcation. Its northern branch becomes the Kuroshio current which begins as a weak and variable current that strengthens at the Luzon Strait . The Kuroshio must travel a larger distance to gain speed than the Mindanao Current which is strong closer to the bifurcation location. It is fed by the southern portion of the NEC. The NEC is a wide current, spanning approximately 10-20°N. Towards 10°N, it

8722-431: The strength of the trade winds was first identified by Jacob Bjerknes in 1969. Bjerknes also hypothesized that ENSO was a positive feedback system where the associated changes in one component of the climate system (the ocean or atmosphere) tend to reinforce changes in the other. For example, during El Niño, the reduced contrast in ocean temperatures across the Pacific results in weaker trade winds, further reinforcing

8820-482: The surface MC (specifically 50 − 150 {\displaystyle 50-150} m {\displaystyle m} depth) varies from season to season. It is stronger during boreal or Northern Hemisphere spring and weaker during fall. From 150 − 400 {\displaystyle 150-400} m {\displaystyle m} , it is stronger in spring and fall and weaker in summer and winter. Seasonal variations in

8918-508: The surface salinity is highest during the 2010/11 El Niño and freshest at the end of the 2010/11 La Niña. The Mindanao Current is difficult to observe and model because of the strength of the current, the extreme topography of the region, and complicating factors such as wind stress fluctuations and eddies. The most extensive observations of the Mindanao Current were performed during the following research programs: El Ni%C3%B1o-Southern Oscillation El Niño–Southern Oscillation ( ENSO )

9016-521: The temperature anomalies and precipitation and weather extremes around the world are clearly increasing and associated with climate change . For example, recent scholarship (since about 2019) has found that climate change is increasing the frequency of extreme El Niño events. Previously there was no consensus on whether climate change will have any influence on the strength or duration of El Niño events, as research alternately supported El Niño events becoming stronger and weaker, longer and shorter. Over

9114-618: The term has evolved and now refers to the warm and negative phase of the El Niño–Southern Oscillation (ENSO). The original phrase, El Niño de Navidad , arose centuries ago, when Peruvian fishermen named the weather phenomenon after the newborn Christ. La Niña ("The Girl" in Spanish) is the colder counterpart of El Niño, as part of the broader ENSO climate pattern . In the past, it was also called an anti-El Niño and El Viejo, meaning "the old man." A negative phase exists when atmospheric pressure over Indonesia and

9212-452: The tropical Pacific Ocean. The low-level surface trade winds , which normally blow from east to west along the equator, either weaken or start blowing from the other direction. El Niño phases are known to happen at irregular intervals of two to seven years, and lasts nine months to two years. The average period length is five years. When this warming occurs for seven to nine months, it is classified as El Niño "conditions"; when its duration

9310-439: The tropical Pacific. Identified by its salinity signature, the MC waters from the surface to 200 {\displaystyle 200} m {\displaystyle m} depth are North Pacific Tropical Water (NPTW) while the layer at 300 − 500 {\displaystyle 300-500} m {\displaystyle m} depth is North Pacific Intermediate water (NPIW). The NPTW

9408-442: The warm waters in the western tropical Pacific are depleted enough so that conditions return to normal. The exact mechanisms that cause the oscillation are unclear and are being studied. Each country that monitors the ENSO has a different threshold for what constitutes an El Niño or La Niña event, which is tailored to their specific interests. El Niño and La Niña affect the global climate and disrupt normal weather patterns, which as

9506-466: The west Pacific is abnormally high and pressure over the east Pacific is abnormally low, during El Niño episodes, and a positive phase is when the opposite occurs during La Niña episodes, and pressure over Indonesia is low and over the west Pacific is high. On average, the temperature of the ocean surface in the tropical East Pacific is roughly 8–10 °C (14–18 °F) cooler than in the tropical West Pacific . The sea surface temperature (SST) of

9604-441: The western and east Pacific. Because the warmer waters of the upper ocean are slightly less dense than the cooler deep ocean, the thicker layer of warmer water in the western Pacific means the thermocline there must be deeper. The difference in weight must be enough to drive any deep water return flow. Consequently, the thermocline is tilted across the tropical Pacific, rising from an average depth of about 140 m (450 ft) in

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