Canary Current and North Equatorial Current from an Inverse Box Model
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Fronts in the World Ocean's Large Marine Ecosystems. ICES CM 2007
- 1 - This paper can be freely cited without prior reference to the authors International Council ICES CM 2007/D:21 for the Exploration Theme Session D: Comparative Marine Ecosystem of the Sea (ICES) Structure and Function: Descriptors and Characteristics Fronts in the World Ocean’s Large Marine Ecosystems Igor M. Belkin and Peter C. Cornillon Abstract. Oceanic fronts shape marine ecosystems; therefore front mapping and characterization is one of the most important aspects of physical oceanography. Here we report on the first effort to map and describe all major fronts in the World Ocean’s Large Marine Ecosystems (LMEs). Apart from a geographical review, these fronts are classified according to their origin and physical mechanisms that maintain them. This first-ever zero-order pattern of the LME fronts is based on a unique global frontal data base assembled at the University of Rhode Island. Thermal fronts were automatically derived from 12 years (1985-1996) of twice-daily satellite 9-km resolution global AVHRR SST fields with the Cayula-Cornillon front detection algorithm. These frontal maps serve as guidance in using hydrographic data to explore subsurface thermohaline fronts, whose surface thermal signatures have been mapped from space. Our most recent study of chlorophyll fronts in the Northwest Atlantic from high-resolution 1-km data (Belkin and O’Reilly, 2007) revealed a close spatial association between chlorophyll fronts and SST fronts, suggesting causative links between these two types of fronts. Keywords: Fronts; Large Marine Ecosystems; World Ocean; sea surface temperature. Igor M. Belkin: Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, Rhode Island 02882, USA [tel.: +1 401 874 6533, fax: +1 874 6728, email: [email protected]]. -
Eddy-Driven Recirculation of Atlantic Water in Fram Strait
PUBLICATIONS Geophysical Research Letters RESEARCH LETTER Eddy-driven recirculation of Atlantic Water in Fram Strait 10.1002/2016GL068323 Tore Hattermann1,2, Pål Erik Isachsen3,4, Wilken-Jon von Appen2, Jon Albretsen5, and Arild Sundfjord6 Key Points: 1Akvaplan-niva AS, High North Research Centre, Tromsø, Norway, 2Alfred Wegener Institute, Helmholtz Centre for Polar and • fl Seasonally varying eddy-mean ow 3 4 interaction controls recirculation of Marine Research, Bremerhaven, Germany, Norwegian Meteorological Institute, Oslo, Norway, Institute of Geosciences, 5 6 Atlantic Water in Fram Strait University of Oslo, Oslo, Norway, Institute for Marine Research, Bergen, Norway, Norwegian Polar Institute, Tromsø, Norway • The bulk recirculation occurs in a cyclonic gyre around the Molloy Hole at 80 degrees north Abstract Eddy-resolving regional ocean model results in conjunction with synthetic float trajectories and • A colder westward current south of observations provide new insights into the recirculation of the Atlantic Water (AW) in Fram Strait that 79 degrees north relates to the Greenland Sea Gyre, not removing significantly impacts the redistribution of oceanic heat between the Nordic Seas and the Arctic Ocean. The Atlantic Water from the slope current simulations confirm the existence of a cyclonic gyre around the Molloy Hole near 80°N, suggesting that most of the AW within the West Spitsbergen Current recirculates there, while colder AW recirculates in a Supporting Information: westward mean flow south of 79°N that primarily relates to the eastern rim of the Greenland Sea Gyre. The • Supporting Information S1 fraction of waters recirculating in the northern branch roughly doubles during winter, coinciding with a • Movie S1 seasonal increase of eddy activity along the Yermak Plateau slope that also facilitates subduction of AW Correspondence to: beneath the ice edge in this area. -
Observations of the North Equatorial Current, Mindanao Current, and Kuroshio Current System During the 2006/ 07 El Niño and 2007/08 La Niña
Journal of Oceanography, Vol. 65, pp. 325 to 333, 2009 Observations of the North Equatorial Current, Mindanao Current, and Kuroshio Current System during the 2006/ 07 El Niño and 2007/08 La Niña 1 2 3 4 YUJI KASHINO *, NORIEVILL ESPAÑA , FADLI SYAMSUDIN , KELVIN J. RICHARDS , 4† 5 1 TOMMY JENSEN , PIERRE DUTRIEUX and AKIO ISHIDA 1Institute of Observational Research for Global Change, Japan Agency for Marine Earth Science and Technology, Natsushima, Yokosuka 237-0061, Japan 2The Marine Science Institute, University of the Philippines, Quezon 1101, Philippines 3Badan Pengkajian Dan Penerapan Teknologi, Jakarta 10340, Indonesia 4International Pacific Research Center, University of Hawaii, Honolulu, HI 96822, U.S.A. 5Department of Oceanography, University of Hawaii, Honolulu, HI 96822, U.S.A. (Received 19 September 2008; in revised form 17 December 2008; accepted 17 December 2008) Two onboard observation campaigns were carried out in the western boundary re- Keywords: gion of the Philippine Sea in December 2006 and January 2008 during the 2006/07 El ⋅ North Equatorial Niño and the 2007/08 La Niña to observe the North Equatorial Current (NEC), Current, ⋅ Mindanao Current (MC), and Kuroshio current system. The NEC and MC measured Mindanao Current, ⋅ in late 2006 under El Niño conditions were stronger than those measured during early Kuroshio, ⋅ 2006/07 El Niño, 2008 under La Niña conditions. The opposite was true for the current speed of the ⋅ 2007/08 La Niña. Kuroshio, which was stronger in early 2008 than in late 2006. The increase in dy- namic height around 8°N, 130°E from December 2006 to January 2008 resulted in a weakening of the NEC and MC. -
On the Connection Between the Mediterranean Outflow and The
FEBRUARY 2001 OÈ ZGOÈ KMEN ET AL. 461 On the Connection between the Mediterranean Out¯ow and the Azores Current TAMAY M. OÈ ZGOÈ KMEN,ERIC P. C HASSIGNET, AND CLAES G. H. ROOTH RSMAS/MPO, University of Miami, Miami, Florida (Manuscript received 18 August 1999, in ®nal form 19 April 2000) ABSTRACT As the salty and dense Mediteranean over¯ow exits the Strait of Gibraltar and descends rapidly in the Gulf of Cadiz, it entrains the fresher overlying subtropical Atlantic Water. A minimal model is put forth in this study to show that the entrainment process associated with the Mediterranean out¯ow in the Gulf of Cadiz can impact the upper-ocean circulation in the subtropical North Atlantic Ocean and can be a fundamental factor in the establishment of the Azores Current. Two key simpli®cations are applied in the interest of producing an eco- nomical model that captures the dominant effects. The ®rst is to recognize that in a vertically asymmetric two- layer system, a relatively shallow upper layer can be dynamically approximated as a single-layer reduced-gravity controlled barotropic system, and the second is to apply quasigeostrophic dynamics such that the volume ¯ux divergence effect associated with the entrainment is represented as a source of potential vorticity. Two sets of computations are presented within the 1½-layer framework. A primitive-equation-based com- putation, which includes the divergent ¯ow effects, is ®rst compared with the equivalent quasigeostrophic formulation. The upper-ocean cyclonic eddy generated by the loss of mass over a localized area elongates westward under the in¯uence of the b effect until the ¯ow encounters the western boundary. -
Surface Circulation2016
OCN 201 Surface Circulation Excess heat in equatorial regions requires redistribution toward the poles 1 In the Northern hemisphere, Coriolis force deflects movement to the right In the Southern hemisphere, Coriolis force deflects movement to the left Combination of atmospheric cells and Coriolis force yield the wind belts Wind belts drive ocean circulation 2 Surface circulation is one of the main transporters of “excess” heat from the tropics to northern latitudes Gulf Stream http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/gulf_stream_modis_lrg.gif 3 How fast ( in miles per hour) do you think western boundary currents like the Gulf Stream are? A 1 B 2 C 4 D 8 E More! 4 mph = C Path of ocean currents affects agriculture and habitability of regions ~62 ˚N Mean Jan Faeroe temp 40 ˚F Islands ~61˚N Mean Jan Anchorage temp 13˚F Alaska 4 Average surface water temperature (N hemisphere winter) Surface currents are driven by winds, not thermohaline processes 5 Surface currents are shallow, in the upper few hundred metres of the ocean Clockwise gyres in North Atlantic and North Pacific Anti-clockwise gyres in South Atlantic and South Pacific How long do you think it takes for a trip around the North Pacific gyre? A 6 months B 1 year C 10 years D 20 years E 50 years D= ~ 20 years 6 Maximum in surface water salinity shows the gyres excess evaporation over precipitation results in higher surface water salinity Gyres are underneath, and driven by, the bands of Trade Winds and Westerlies 7 Which wind belt is Hawaii in? A Westerlies B Trade -
The Equatorial Current System
The Equatorial Current System C. Chen General Physical Oceanography MAR 555 School for Marine Sciences and Technology Umass-Dartmouth 1 Two subtropic gyres: Anticyclonic gyre in the northern subtropic region; Cyclonic gyre in the southern subtropic region Continuous components of these two gyres: • The North Equatorial Current (NEC) flowing westward around 20o N; • The South Equatorial Current (SEC) flowing westward around 0o to 5o S • Between these two equatorial currents is the Equatorial Counter Current (ECC) flowing eastward around 10o N. 2 Westerly wind zone 30o convergence o 20 N Equatorial Current EN Trade 10o divergence Equatorial Counter Current convergence o -10 S. Equatorial Current ES Trade divergence -20o convergence -30o Westerly wind zone 3 N.E.C N.E.C.C S.E.C 0 50 Mixed layer 100 150 Thermoclines 200 25oN 20o 15o 10o 5o 0 5o 10o 15o 20o 25oS 4 Equatorial Undercurrent Sea level East West Wind stress Rest sea level Mixed layer lines Thermoc • At equator, f =0, the current follows the wind direction, and the wind drives the water to move westward; • The water accumulates against the western boundary and cause the sea level rises over there; • The surface pressure gradient pushes the water eastward and cancels the wind-driven westward currents in the mixed layer. 5 Wind-induced Current Pressure-driven Current Equatorial Undercurrent Mixed layer Thermoclines 6 Observational Evidence 7 Urbano et al. (2008), JGR-Ocean, 113, C04041, doi: 10.1029/2007/JC004215 8 Observed Seasonal Variability of the EUC (Urbano et al. 2008) 9 Equatorial Undercurrent in the Pacific Ocean Isotherms in an equatorial plane in the Pacific Ocean (from Philander, 1980) In the Pacific Ocean, it is called “the Cormwell Current}; In the Atlantic Ocean, it is called “the Lomonosov Current” 10 Kessler, W, Progress in Oceanography, 69 (2006) 11 In the equatorial Pacific, when the South-East Trade relaxes or turns to the east, the sea surface slope will “collapse”, causing a flat mixed layer and thermocline. -
Trophic Diversity of Plankton in the Epipelagic and Mesopelagic Layers of the Tropical and Equatorial Atlantic Determined with Stable Isotopes
diversity Article Trophic Diversity of Plankton in the Epipelagic and Mesopelagic Layers of the Tropical and Equatorial Atlantic Determined with Stable Isotopes Antonio Bode 1,* ID and Santiago Hernández-León 2 1 Instituto Español de Oceanografía, Centro Oceanográfico de A Coruña, Apdo 130, 15080 A Coruña, Spain 2 Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de las Palmas de Gran Canaria, Campus de Taliarte, Telde, Gran Canaria, 35214 Islas Canarias, Spain; [email protected] * Correspondence: [email protected]; Tel.: +34-981205362 Received: 30 April 2018; Accepted: 12 June 2018; Published: 13 June 2018 Abstract: Plankton living in the deep ocean either migrate to the surface to feed or feed in situ on other organisms and detritus. Planktonic communities in the upper 800 m of the tropical and equatorial Atlantic were studied using the natural abundance of stable carbon and nitrogen isotopes to identify their food sources and trophic diversity. Seston and zooplankton (>200 µm) samples were collected with Niskin bottles and MOCNESS nets, respectively, in the epipelagic (0–200 m), upper mesopelagic (200–500 m), and lower mesopelagic layers (500–800 m) at 11 stations. Food sources for plankton in the productive zone influenced by the NW African upwelling and the Canary Current were different from those in the oligotrophic tropical and equatorial zones. In the latter, zooplankton collected during the night in the mesopelagic layers was enriched in heavy nitrogen isotopes relative to day samples, supporting the active migration of organisms from deep layers. Isotopic niches showed also zonal differences in size (largest in the north), mean trophic diversity (largest in the tropical zone), food sources, and the number of trophic levels (largest in the equatorial zone). -
The Canary Current Temperatures from Portugal to Cape Most Reliable Indicators
V. Sediments and benthos Rapp. P.-v. Réun. Cons. int. Explor. Mer, 180: 315-322. 1982. Sediments in up welling areas, particularly off Northwest Africa Eugen Seibold Geologisch-Paläontologisches Institut der Universität Kiel Olshausenstrasse 40/60, 2300 Kiel 1, Bundesrepublik Deutschland Introduction Oceanic upwelling supplies water from subsurface lay with sediments, however, most of these variations, ers to the surface layer and may occur as a persistent together with biological production cycles, are aver process anywhere, although it is a particularly con aged out, as even the uppermost centimetre of sedi spicuous phenomenon along western coasts of conti ment normally includes events spanning a century or nents where prevailing winds drive the surface water more. Most of the indicators employed are of organic from the coast (Smith, 1973). origin. It is well established that typical upwelling This paper discusses indicators of coastal upwelling water masses are several degrees cooler than nearby revealed in the underlying sediments off Northwest waters, are less saline, show a relatively low oxygen Africa and makes some comparisons with upwelling content, and have higher nutrient concentrations, effects in sediments from the coastal area off Southwest increasing primary production in the photic zone. At Africa. From these results it will be attempted to present only lowered temperatures as preserved in reconstruct periods of upwelling during the last 20 mil planktonic organisms tests can be used as clear indi lion years off Northwest Africa. Some of these prob cators for upwelling, although higher productivity may lems have been treated generally in the classic paper of provide additional hints. -
The Coastal-Ocean Transition Zone in the Canary Current System S Hernández-León1([email protected]), J.M
The coastal-ocean transition zone in the Canary Current system s Hernández-León1([email protected]), J.M. Rodríguez2, M. Moyano1and J. Arístegui1 1Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain 21nstituto Español de Oceanografía, Gijón, Asturias, Spain During the last decade, the institutions engaged in marine upwelling filaments in the transport of zooplankton and fish science in the Canary Islands have collaborated in the larvae from the northwest African shelf to the islands, 6) the development of a science strategy related to GLOBEC. The distribution and evaluation of fish biomass using acoustics objectives attained were 1) the retrospective analysis of data around oceanic islands, and 7) the interplay between the about zooplankton taxonomy, abundance and biomass, 2) the physical variability and predation by the deep scattering layers development of new methods for the study of zooplankton and fish on the development of fish stocks in the area. growth and metabolism, 3) the study of the role of the deep scattering layers in the structure of the pelagic ecosystem in The Canary Current is the easternmost branch of the North oceanic waters, 4) the mesoscale variability due to the effect Atlantic subtropical gyre flowing southward. The most important of eddies shed by the Canary Islands and their effect in the characteristic of the region is the presence of the large upwelling accumulation of zooplankton and fish larvae, 5) the effect of area off the northwest African coast. High chlorophyll and 26 GLOBEC INTERNATIONAL NEWSLETTER OCTOBER 2007 primary production normally observed in coastal waters due 0 2900 N r-------------------"'"'I' to upwelling, decrease rapidly towards the ocean. -
EBSA Template 1 Costa Rica Dome-En
Appendix Template for Submission of Scientific Information to Describe Ecologically or Biologically Significant Marine Areas Note: Please DO NOT embed tables, graphs, figures, photos, or other artwork within the text manuscript, but please send these as separate files. Captions for figures should be included at the end of the text file, however . Title/Name of the area: Costa Rica Dome Presented by (names, affiliations, title, contact details) Abstract (in less than 150 words) The Costa Rica Dome is an area of high primary productivity in the northeastern tropical Pacific, which supports marine predators such as tuna, dolphins, and cetaceans. The endangered leatherback turtle (Dermochelys coriacea ), which nests on the beaches of Costa Rica, migrates through the area. The Costa Rica Dome provides year-round habitat that is important for the survival and recovery of the endangered blue whale (Balaenoptera musculus ). The area is of special importance to the life history of a population of the blue whales, which migrate south from Baja California during the winter for breeding, calving, raising calves and feeding. Introduction (To include: feature type(s) presented, geographic description, depth range, oceanography, general information data reported, availability of models) Biological hot spots in the ocean are often created by physical processes and have distinct oceanographic signatures. Marine predators, including large pelagic fish, marine mammals, seabirds, and fishing vessels, recognize that prey organisms congregate at ocean fronts, eddies, and other physical features (Palacios et al, 2006). One such hot spot occurs in the northeastern tropical Pacific at the Costa Rica Dome. The Costa Rica Dome was first observed in 1948 (Wyrtki, 1964) and first described by Cromwell (1958). -
I-3 Canary Current: LME #27
I-3 Canary Current: LME #27 S. Heileman and M. Tandstad The Canary Current LME is a major upwelling region off the coast of northwest Africa, bordered by Morocco, Mauritania, Senegal, Guinea-Bissau, the Canary Islands (Spain), Gambia, Cape Verde and Western Sahara (a disputed, non-self governing territory). It is strongly influenced by the Canary Current, which flows along the African coast from north to south between 30° N – 10° N and offshore to 20° W (Barton 1998). The surface waters of the Canary Current are relatively cool as a result of the entrainment of upwelled water from the coast as it flows southwards (Mittelstaedt 1991). Several drainage systems in this region flow only seasonally because of the high seasonal variation in rainfall, e.g., the Senegal and Gambia Rivers. The LME has an area of about 1.1 million km2, of which 0.77% is protected, and contains 0.12% of the world’s sea mounts and 0.01% of the world’s coral reefs (Sea Around Us 2007). There are 7 major estuaries and river systems draining into the LME including the Casamance, Senegal and Gambia. Books, book chapters and reports pertaining to the LME include Bas (1993), Prescott (1993), Roy & Cury (2003), Chavance et al. (2004) and UNEP (2005). I. Productivity The Canary Current LME is a Class I, highly productive ecosystem (>300 gCm-2y-1). Hydrographic and climatic conditions play a major role in driving the dynamics of this LME, which shows seasonal and longer-term variations (Bas 1993, Roy & Cury 2003). Climatic variability is the primary driving force, with intensive fishing being the secondary driving force, of biomass changes in the LME (FAO 2003, Sherman 2003). -
Poleward Shift of the Pacific North Equatorial Current Bifurcation
RESEARCH ARTICLE Poleward Shift of the Pacific North Equatorial 10.1029/2019JC015019 Current Bifurcation Key Points: Haihong Guo1,2 , Zhaohui Chen1,2 , and Haiyuan Yang1,2 • In the North Pacific, the North Equatorial Current bifurcation in 1Physical Oceanography Laboratory/Institute for Advanced Ocean Study, Ocean University of China, Qingdao, China, the upper ocean shifts poleward 2 with increasing depth Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China • The poleward shift of the bifurcation is associated with the asymmetric wind stress curl input to Abstract The dynamics of the poleward shift of the Pacific North Equatorial Current bifurcation latitude tropical/subtropical gyre ‐ • (NBL) is studied using a 5.5 layer reduced gravity model. It is found that the poleward shift of the NBL is The equatorial currents bifurcations fi in other basins share the same associated with the asymmetric intensity of the wind stress curl input to the Paci c tropical and subtropical vertical structure gyres. Stronger wind stress curl in the subtropical gyre leads to equatorward transport in the interior upper ocean across the boundary between the two gyres, causing a poleward transport compensation at the western boundary. In the lower layer ocean, in turn, there is poleward (equatorward) transport at the Correspondence to: interior (western boundary) due to Sverdrup balance which requires zero transport at the gyre boundary Z. Chen, where zonally integrated wind stress curl is zero. Therefore, the NBL exhibits a titling feature, with its [email protected] position being more equatorward in the upper layer and more poleward in the lower layer.