Loop Current

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A map of the Loop Current Loop current2.jpg
A map of the Loop Current

A parent to the Florida Current, the Loop Current is a warm ocean current that flows northward between Cuba and the Yucatán Peninsula, moves north into the Gulf of Mexico, loops east and south before exiting to the east through the Florida Straits and joining the Gulf Stream. The Loop Current is an extension of the western boundary current of the North Atlantic subtropical gyre. [1] Serving as the dominant circulation feature in the Eastern Gulf of Mexico, the Loop Currents transports between 23 and 27 sverdrups [2] and reaches maximum flow speeds of from 1.5 to 1.8 meters/second. [3]

Florida Current A thermal ocean current that flows from the Straits of Florida around the Florida Peninsula and along the southeastern coast of the United States before joining the Gulf Stream near Cape Hatteras

The Florida Current is a thermal ocean current that flows from the Straits of Florida around the Florida Peninsula and along the southeastern coast of the United States before joining the Gulf Stream Current near Cape Hatteras. Its contributing currents are the Loop Current and the Antilles Current. The current was discovered by Spanish explorer Juan Ponce de León in 1513.

Ocean current Directional mass flow of oceanic water generated by external or internal forces

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, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements.

Cuba Country in the Caribbean

Cuba, officially the Republic of Cuba, is a country comprising the island of Cuba as well as Isla de la Juventud and several minor archipelagos. Cuba is located in the northern Caribbean where the Caribbean Sea, Gulf of Mexico and Atlantic Ocean meet. It is east of the Yucatán Peninsula (Mexico), south of both the U.S. state of Florida and the Bahamas, west of Haiti and north of both Jamaica and the Cayman Islands. Havana is the largest city and capital; other major cities include Santiago de Cuba and Camagüey. The area of the Republic of Cuba is 110,860 square kilometers (42,800 sq mi). The island of Cuba is the largest island in Cuba and in the Caribbean, with an area of 105,006 square kilometers (40,543 sq mi), and the second-most populous after Hispaniola, with over 11 million inhabitants.


A related feature is an area of warm water with an "eddy" or "Loop Current ring" that separates from the Loop Current, somewhat randomly every 3 to 17 months. [4] Swirling at 1.8 to 2 meters/second, these rings drift to the west at speeds of 2 to 5 kilometers/day and have a lifespan of up to a year before they bump into the coast of Texas or Mexico. [5] These eddies are composed of warm Caribbean waters and possess physical properties that isolate the masses from surrounding Gulf Common Waters. The rings can measure 200 to 400 kilometers in diameter and extend down to a depth of 1000 meters. [6]

Eddy (fluid dynamics) The swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime

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 behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is naturally observed behind large emergent rocks in swift-flowing rivers.

Texas U.S. state in the United States

Texas is the second largest state in the United States by both area and population. Geographically located in the South Central region of the country, Texas shares borders with the U.S. states of Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the southwest, and has a coastline with the Gulf of Mexico to the southeast.

Mexico Country in the southern portion of North America

Mexico, officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost 2,000,000 square kilometers (770,000 sq mi), the nation is the fourth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 129 million people, Mexico is the tenth most populous country and the most populous Spanish-speaking country in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states plus Mexico City (CDMX), which is the capital city and its most populous city. Other metropolises in the country include Guadalajara, Monterrey, Puebla, Toluca, Tijuana, and León.

Effect on tropical cyclones

Around 1970, it was believed that the Loop Current exhibited an annual cycle in which the Loop feature extended farther to the north during the summer. Further study over the past few decades, however, has shown that the extension to the north (and the shedding of eddies) does not have a significant annual cycle, but does vacillate in the north-south and east-west directions on an inter-annual basis. [7]

The Loop Current and its eddies may be detected by measuring sea surface level. Sea surface level of both the eddies and the Loop on September 21, 2005 was up to 60 cm (24 in) higher than surrounding water, indicating a deep area of warm water beneath them. [8] On that day, Hurricane Rita passed over the Loop current and intensified into a Category 5 storm with the help of the warm water.

Hurricane Rita Category 5 Atlantic hurricane in 2005

Hurricane Rita was the fourth-most intense Atlantic hurricane ever recorded and the most intense tropical cyclone ever observed in the Gulf of Mexico. Part of the record-breaking 2005 Atlantic hurricane season, which included three of the top ten most intense Atlantic hurricanes ever recorded, Rita was the seventeenth named storm, tenth hurricane, and fifth major hurricane of the 2005 season. Rita formed near The Bahamas from a tropical wave on September 18, 2005 that originally developed off the coast of West Africa. It moved westward, and after passing through the Florida Straits, Rita entered an environment of abnormally warm waters. Moving west-northwest, it rapidly intensified to reach peak winds of 180 mph (285 km/h), achieving Category 5 status on September 21st. However, it weakened to a Category 3 hurricane before making landfall in Johnson's Bayou, Louisiana, between Sabine Pass, Texas and Holly Beach, Louisiana, with winds of 115 mph (185 km/h). Rapidly weakening over land, Rita degenerated into a large low-pressure area over the lower Mississippi Valley by September 26th.

In the Gulf of Mexico, the deepest areas of warm water are associated with the Loop Current and the rings of current that have separated from the Loop Current are commonly called Loop Current eddies. The warm waters of the Loop Current and its associated eddies provide more energy to hurricanes and allow them to intensify.

As hurricanes pass over warm areas of the Gulf of Mexico, they convert the ocean's heat into storm energy. As this energy is removed from the seas, a wake of colder water can be detected along the hurricane's path. This is because heat is withdrawn from the ocean mixed layer in a number of ways. For instance, sensible and latent heat are lost directly to the tropical cyclone across the air-sea interface. Also, the horizontal divergence of wind-driven mixed layer currents results in the upwelling of colder thermocline water. Finally, the turbulent entrainment of colder thermocline waters caused by wind stirring also results in the cooling of the surface waters. [9] These are the reasons that the depth of the ocean mixed layer is more important in hurricane deepening than sea surface temperature. A thin veneer of warm surface waters will be more susceptible to hurricane induced cooling than waters with a larger mixed layer and deeper thermocline. Furthermore, models suggest that cyclones are more likely to reach a larger fraction of their maximum potential intensity over warm oceanic features where the 26 °C isotherm extends beyond 100 meters. [10] [11]

An example of how deep warm water, including the Loop Current, can allow a hurricane to strengthen, if other conditions are also favorable, is Hurricane Camille, which made landfall on the Mississippi Gulf Coast in August 1969. Camille formed in the deep warm waters of the Caribbean, which enabled it to rapidly intensify into a category 3 hurricane in one day. It rounded the western tip of Cuba, and its path took it directly over the Loop Current, all the way north towards the coast, during which time the rapid intensification continued. Camille became a category 5 hurricane, with an intensity rarely seen, and extremely high winds that were maintained until landfall (190 mph (310 km/h) sustained winds were estimated to have occurred in a very small area to the right of the eye).

Hurricane Camille Category 5 Atlantic hurricane in 1969

Hurricane Camille was the second most intense tropical cyclone on record to strike the United States. The most intense storm of the 1969 Atlantic hurricane season, Camille originated as a tropical depression on August 14, south of Cuba, from a long-tracked tropical wave. Located in a favorable environment for strengthening, the storm quickly intensified into a Category 2 hurricane before striking the western part of Cuba on August 15. Emerging into the Gulf of Mexico, Camille underwent another period of rapid intensification and became a Category 5 hurricane the next day as it moved northward towards the Louisiana–Mississippi region. Despite weakening slightly on August 17, the hurricane quickly re-intensified back into a Category 5 hurricane before it made landfall a half-hour before midnight in Bay St. Louis, Mississippi. At peak intensity, the hurricane had a minimum pressure of 900 mbar (26.58 inHg). This was the second-lowest pressure recorded for a U.S. landfall. Only the 1935 Labor Day hurricane had a lower pressure at landfall. As Camille pushed inland, it quickly weakened and was a tropical depression by the time it was over the Ohio Valley. Once it emerged offshore, Camille was able to restrengthen to a strong tropical storm, before it became extratropical on August 22. Camille was subsequently absorbed by a frontal storm over the North Atlantic on the same day.

Mississippi Gulf Coast Coastline

The Mississippi Gulf Coast, also known as the Mississippi Gulf Coast region, Coastal Mississippi, or simply The Coast, is the area of southern Mississippi along the Mississippi Sound along the Gulf Of Mexico.

In 1980, Hurricane Allen strengthened to a category 5 hurricane while moving over the Loop Current, but it weakened before landfall in Texas.

In 2005, Hurricane Katrina and Hurricane Rita both greatly increased in strength when they passed over the warmer waters of the Loop Current. Hurricane Wilma of 2005 was expected to make its Florida landfall as a category 2 hurricane, but after encountering the southeastern portion of the Loop Current, it reached the Florida coast as a category 3 instead. [12]

While not as infamous as Katrina, Hurricane Opal most definitively illustrates the deepening abilities of a warm core ring. After crossing the Yucatan peninsula, Opal reentered the Gulf of Mexico and passed over an eddy shed by the Loop Current. Within a fourteen-hour period, sea surface pressure dropped from 965 to 916 hectaPasals, surface winds increased from 35 to 60 meters/second, and the storm condensed from a radius of 40 kilometers to 25 kilometers. Prior to the storm, the 20 °C isotherm was located at a depth between 175 and 200 meters, but was found 50 meters shallower after the storm had passed. While the majority of this hurricane induced cooling of the mixed layer was attributed to upwelling (due to Ekman divergence), another 2000 to 3000 watts/meter squared were estimated to be lost through heat flux at the air-water interface of the storm's core. Furthermore, buoy-derived sea surface temperature readings recorded temperature dropping 2° to 3 °C as Opal passed over Gulf Common Waters, but only 0.5° to 1 °C as the storm encountered the more massive ocean mixed layer associated with the warm core eddy. [13]

In 2008, Hurricane Gustav transited the Loop Current, but due to the current's temperature (then only in the high 80's-degrees-F) and truncated size (extending only halfway from Cuba to Louisiana, with cooler water in-between its tip and the Louisiana coast) the storm remained a category 3 hurricane instead of increasing strength as it passed over the current. [14] [15]

Hurricane Ivan rode the Loop Current twice in 2004.


Hurricane strengthening and weakening is the product of extensive thermodynamic interactions between the atmosphere and the ocean. Generally speaking, the evolution of a hurricane's intensity is determined by three factors. First, the initial intensity of a tropical cyclone is a predominant factor and its strength will be reflected throughout the storm's life. Second, the thermodynamic state of the atmosphere through which the cyclone moves will affects its ability to strengthen, as strong horizontal winds will disperse internal circulation and prevent the vertical stacking of energy within the storm. The third component affecting hurricane intensity is the heat exchange between the upper layer of ocean waters and the core of the storm. [16] For this reason, a major focus of hurricane research has been sea surface temperature prior to a storm. However, recent studies have revealed that surface temperature is less important in hurricane deepening than the depth of the ocean mixed layer. In fact, a hurricane's sea level pressure has been shown to be more closely correlated with the 26 °C isotherm depth (and oceanic heat content) than the sea surface temperature. [17] Storms passing over the Loop Current or warm core eddies have access to more tepid water, and therefore the higher energy content of the heated molecules.

Once Hurricane Rita left the Loop Current and passed over cooler water, it declined in strength, but the main factor in this weakening was an eyewall replacement cycle (ERC) occurring at that time. The ERC and other atmospheric factors are why Rita did not reintensify when subsequently passing over the eddy vortex.

Also of note: tropical depressions, tropical storms, and hurricanes gain strength from, but are not steered by, the temperature of the water. They are steered by the atmosphere, and the atmospheric level involved in steering a hurricane is different at different intensities (i.e., it relates to the minimum pressure of the hurricane).

Sea level and sea temperature

Sea level is relatively easy to measure accurately using radars from satellites. Sea temperature below the surface is not as easy to measure widely, but can be inferred from the sea level since warmer water expands and thus (all other factors, such as water depth, being equal) a vertical column of water will rise slightly higher when warmed. Thus sea level is often used as a proxy for deep sea temperatures.

NOAA's National Data Buoy Center maintains a large number of data buoys in the Gulf of Mexico, some of which measure sea temperature one meter below the surface.


The Loop Current and Loop Current Eddies affect biological communities within the Gulf of Mexico. In general, however, it is not the warm-core Loop Current and eddies themselves that affect these communities. Instead, it is the smaller cold-core features known as Frontal Eddies that form around the boundary of the Loop Current and Loop Current Eddies, which affect biological communities in the Gulf.

Loop Current Frontal Eddies are cold-core, counter-clockwise rotating (cyclonic) eddies that form on or near the boundary of the Loop Current. LCFEs range from about 80 km to 120 km in diameter. [18] These cold features are smaller than the warm-core eddies shed from the Loop Current.

Multiple studies have shown differences in biological communities inside versus outside of the various features in the Gulf of Mexico. Higher standing stocks of zooplankton and micronekton were found in cold-core features than in both the Loop Current and the Loop Current Eddies. [19] However, no difference in the abundance of euphausiids, planktonic shrimp-like marine crustaceans, was found between areas of upwelling and warm-core eddies, [20] but in 2004 the hyperiid abundance was found to be lower within Loop Current Eddies as opposed to outside. [21] Concurrently, it was found that nutrient (nitrate) levels were low above 100 meters within warm-core eddies, while nitrate levels were high within cold features. [22] [23] Low standing stock of chlorophyll, primary production, and zooplankton biomass was found to be low in LCEs. [24]

Low chlorophyll concentrations and primary production are likely a result of low nutrients levels, as many planktonic species require nitrate and other nutrients to survive. In turn, low primary production could be one cause of heterotrophic (organism-eating, as opposed to photosynthetic) species abundances being low inside the Loop Current and Loop Current Eddies. Alternatively, temperature may play a role for low abundances of both communities: Atlantic Blue Fin Tuna have developed behavioral patterns of avoiding the high temperatures associated with warm-core features, such as the Loop Current and Loop Current Eddies, in the Gulf of Mexico. [25] It is possible, also, that planktonic species likewise avoid the higher temperatures in these features.

See also

Related Research Articles

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Cyclone large scale air mass that rotates around a strong center of low pressure

In meteorology, a cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure. Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes, and dust devils lie within smaller mesoscale. Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the tropical upper tropospheric trough during the summer months in the Northern Hemisphere. Cyclones have also been seen on extraterrestrial planets, such as Mars, Jupiter, and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones. These zones contract and form weather fronts as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones occlude as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical jet stream.

Subtropical cyclone Meteorological phenomenon

A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone.

Thermohaline circulation A part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes

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 temperature and -haline referring to salt content, factors which together determine the density of sea water. Wind-driven surface currents travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes. This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. The water in these circuits transport both energy and mass around the globe. As such, the state of the circulation has a large impact on the climate of the Earth.

A hypercane is a hypothetical class of extreme tropical cyclone that could form if ocean temperatures reached approximately 50 °C (122 °F), which is 15 °C (27 °F) warmer than the warmest ocean temperature ever recorded. Such an increase could be caused by a large asteroid or comet impact, a large supervolcanic eruption, a large submarine flood basalt, or extensive global warming. There is some speculation that a series of hypercanes resulting from an impact by a large asteroid or comet contributed to the demise of the non-avian dinosaurs. The hypothesis was created by Kerry Emanuel of MIT, who also coined the term.

Sea surface temperature Water temperature close to the oceans surface

Sea surface temperature (SST) is the water temperature close to the ocean's surface. The exact meaning of surface varies according to the measurement method used, but it is between 1 millimetre (0.04 in) and 20 metres (70 ft) below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a short distance of the shore. Localized areas of heavy snow can form in bands downwind of warm water bodies within an otherwise cold air mass. Warm sea surface temperatures are known to be a cause of tropical cyclogenesis over the Earth's oceans. Tropical cyclones can also cause a cool wake, due to turbulent mixing of the upper 30 metres (100 ft) of the ocean. SST changes diurnally, like the air above it, but to a lesser degree. There is less SST variation on breezy days than on calm days. In addition, ocean currents such as the Atlantic Multidecadal Oscillation (AMO), can effect SST's on multi-decadal time scales, a major impact results from the global thermohaline circulation, which affects average SST significantly throughout most of the world's oceans.

Kuroshio Current North flowing ocean current on the west side of the North Pacific Ocean

The Kuroshio (黒潮), also known as the Black or Japan Current or the Black Stream, is a north-flowing ocean current on the west side of the North Pacific Ocean. It is similar to the Gulf Stream in the North Atlantic and is part of the North Pacific ocean gyre. Like the Gulf stream, it is a strong western boundary current.

Norwegian Current A current that flows northeasterly along the Atlantic coast of Norway into the Barents Sea

The Norwegian Current is a water current that flows northeasterly along the Atlantic coast of Norway at depths of between 50 and 100 metres through the Barents Sea Opening into the Barents Sea. It contrasts with the North Atlantic Current because it is colder and contains less salt, having most of its tributary water coming from the slightly brackish North and Baltic seas, as well as the Norwegian fjords and rivers. It is, however, considerably warmer and saltier than the Arctic Ocean, which is freshened by the ice in and around it. Winter temperatures in the Norwegian current are typically between 2 and 5 °C whereas the temperature of the Atlantic water exceeds 6 °C.

Atlantic hurricane tropical cyclone that forms in the North Atlantic Ocean

An Atlantic hurricane or tropical storm is a tropical cyclone that forms in the Atlantic Ocean, usually between the months of June and November. A hurricane differs from a cyclone or typhoon only on the basis of location. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, and a cyclone occurs in the south Pacific or Indian Ocean.

Shutdown of thermohaline circulation An effect of global warming on a major ocean circulation.

A shutdown or slowdown of the thermohaline circulation is a hypothesized effect of global warming on a major ocean circulation.

Tropical cyclogenesis

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Tropical cyclone Rotating storm system with a closed, low-level circulation

A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean, and a typhoon occurs in the northwestern Pacific Ocean; in the south Pacific or Indian Ocean, comparable storms are referred to simply as "tropical cyclones" or "severe cyclonic storms".

Warm core ring A type of mesoscale eddy which breaks off from a warm ocean current. The ring is an independent circulatory system of warm water which can persist for several months

A warm core ring is a type of mesoscale eddy which breaks off from an ocean current, e.g. the Gulf Stream or the Kuroshio Current. The ring is an independent circulatory system of warm water which can persist for several months. The rest of this article will use the Gulf Stream by way of an example but these mesoscale eddies also form in most powerful ocean currents, such as the Kuroshio or Agulhas currents.

Gulf Stream A warm, swift Atlantic current that originates in the Gulf of Mexico flows around the tip of Florida, along the east coast of the United States before crossing the Atlantic Ocean

The Gulf Stream, together with its northern extension the North Atlantic Drift, is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and stretches to the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean. The process of western intensification causes the Gulf Stream to be a northward accelerating current off the east coast of North America. At about 40°0′N30°0′W, it splits in two, with the northern stream, the North Atlantic Drift, crossing to Northern Europe and the southern stream, the Canary Current, recirculating off West Africa.

West Spitsbergen Current A warm, salty current that runs poleward just west of Spitsbergen

The West Spitsbergen Current (WSC) is a warm, salty current that runs poleward just west of Spitsbergen,, in the Arctic Ocean. The WSC branches off the Norwegian Atlantic Current in the Norwegian Sea. The WSC is of importance because it drives warm and salty Atlantic Water into the interior Arctic. The warm and salty WSC flows north through the eastern side of Fram Strait, while the East Greenland Current (EGC) flows south through the western side of Fram Strait. The EGC is characterized by being very cold and low in salinity, but above all else it is a major exporter of Arctic sea ice. Thus, the EGC combined with the warm WSC makes the Fram Strait the northernmost ocean area having ice-free conditions throughout the year in all of the global ocean.

Eyewall replacement cycle

Eyewall replacement cycles, also called concentric eyewall cycles, naturally occur in intense tropical cyclones, generally with winds greater than 185 km/h (115 mph), or major hurricanes. When tropical cyclones reach this intensity, and the eyewall contracts or is already sufficiently small, some of the outer rainbands may strengthen and organize into a ring of thunderstorms—an outer eyewall—that slowly moves inward and robs the inner eyewall of its needed moisture and angular momentum. Since the strongest winds are in a cyclone's eyewall, the tropical cyclone usually weakens during this phase, as the inner wall is "choked" by the outer wall. Eventually the outer eyewall replaces the inner one completely, and the storm may re-intensify.

Cold-core rings are a type of oceanic eddy, which are characterized as unstable, time-dependent swirling ‘cells’ that separate from their respective ocean current and move into water bodies with different physical, chemical, and biological characteristics. Their size can range from 1 mm to over 10,000 km in diameter with depths over 5 km. Cold-core rings are the product of warm water currents wrapping around a colder water mass as it breaks away from its respective current. The direction an eddy swirls can be categorized as either cyclonic or anticyclonic depending on the hemisphere. A counterclockwise movement of water in the Northern hemispheres is cyclonic, but the same counterclockwise movement is anticyclonic in the Southern hemisphere. Although eddies have large amounts of kinetic energy, their rotation is relatively quick to diminish in relation to the amount of viscous friction in water. They typically last for a few weeks to a year. The nature of eddies are such that the center of the eddy, the outer swirling ring, and the surrounding waters are well stratified and all maintain their distinct properties throughout the eddy’s short time-scale.

Haida Eddies

Haida Eddies are episodic, clockwise rotating ocean eddies that form during the winter off the west coast of British Columbia’s Haida Gwaii and Alaska’s Alexander Archipelago. These eddies are notable for their large size, persistence, and frequent recurrence. Rivers flowing off the North American continent supply the continental shelf in the Hecate Strait with warmer, fresher, and nutrient-enriched water. Haida eddies are formed every winter when this rapid outflow of water through the strait wraps around Cape St. James at the southern tip of Haida Gwaii, and meets with the cooler waters of the Alaska Current. This forms a series of plumes which can merge into large eddies that are shed into the northeast Pacific Ocean by late winter, and may persist for up to two years.

Papagayo Jet

The Papagayo jet, also referred to as the Papagayo Wind or the Papagayo Wind Jet, are strong intermittent winds that blow approximately 70 km north of the Gulf of Papagayo, after which they are named. The jet winds travel southwest from the Caribbean and the Gulf of Mexico to the Pacific Ocean through a pass in the Cordillera mountains at Lake Nicaragua. The jet follows the same path as the northeast trade winds in this region; however, due to a unique combination of synoptic scale meteorology and orographic phenomena, the jet winds can reach much greater speeds than their trade wind counterparts. That is to say, the winds occur when cold high-pressure systems from the North American continent meet warm moist air over the Caribbean and Gulf of Mexico, generating winds that are then funneled through a mountain pass in the Cordillera. The Papagayo jet is also not unique to this region. There are two other breaks in the Cordillera where this same phenomenon occurs, one at the Chivela Pass in México and another at the Panama Canal, producing the Tehuano (Tehuantepecer) and the Panama jets respectively.


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