Observations of the Mindanao Current during the western equatorial Pacific Ocean circulation study

Lukas, Roger; Firing, Eric; Hacker, Peter; Richardson, Philip L.; Collins, Curtis A.; Fine, Rana A.; Gammon, Richard H.

doi:10.1029/91jc00062

Cited by 253 publications

(188 citation statements)

References 24 publications

(14 reference statements)

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“…A role for the equatorial Pacific in glacial cycles is suggested by the extraordinary capacity of the Southern Ocean to trap Si(OH) 4 that would otherwise be transported north to the equatorial Pacific, and the capacity of diatoms to export carbon to the deep ocean due to their relatively large size (Michaels and Silver, 1988 ) from WEPOCS III data (Lukas et al, 1991). Fig.…”

Section: Connections Between the Southern Ocean And The Equatorial Pamentioning

confidence: 99%

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Dugdale

Wilkerson

2001

Sci. Mar.

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INTRODUCTIONThe biogeochemistry of silicon (Si) is the focus of considerable contemporary attention by geochemists, paleoceanographers and paleoclimatologists. Biologists are showing revived interest in the Si cycle in relation to diatom productivity as it's very strong role in marine productivity (e.g. Smetacek, 1999) and effect on ocean-atmosphere processes becomes apparent, following a period in which the focus was almost exclusively on smaller and smaller planktonic organisms. The objective of this communication is to review the role of biological processes in the formation of the ocean Si environment first at the broad scale and then in more detail in two special settings, the equatorial Pacific and the Southern Ocean. In doing so, we will follow the evolution of a set of nitrogen (N) based models, that conclude with inclusion of Si and it's impact on global carbon cycles and paleoclimatology. We will examine the differences between the oceanic Si and N cycle, the existence of areas of unusually low silicate relative to nitrate concentrations and how we think they are formed. The concept of the Pacific equatorial upwelling area as a Si limited chemostatlike system and the model complexity necessary to describe its functioning will be presented. SUMMARY: Diatoms with their fast growth rates and obligate requirement for Si have a unique relationship to the oceanic Si cycle with the potential for controlling the nutrient and CO 2 environment of large important areas of the ocean. The new production of diatoms based on both new nitrogen and Si sources is described using a Si-pump based upon the differential regeneration of the two elements. This approach, applied to the eastern equatorial Pacific, showed diatoms to respond as in a Si-limited chemostat, to the low source Si(OH) 4 in the Equatorial UnderCurrent. Increased Si(OH) 4 results in increased diatom productivity, suppression of non-diatom populations and decreased surface pCO 2 . The deficiency in source concentrations of Si(OH) 4 results from low Si(OH) 4 :NO 3 water originating in the vicinity of the Antarctic Polar Front, a consequence of the extraordinary trapping of Si by the Southern Ocean. In glacial periods this trapping is reduced several fold and likely results in increased Si(OH) 4 export to the north, and increased Si(OH) 4 production and deposition at the equatorial Pacific which can be expected to reduce surface pCO 2 . The connections between the eastern equatorial Pacific export production and Southern Ocean Si trapping may provide a major biogeochemical feedback system with implications for contemporary and paleoclimatology.

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Section: Connections Between the Southern Ocean And The Equatorial Pamentioning

confidence: 99%

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Dugdale

Wilkerson

2001

Sci. Mar.

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“…Therefore, several ocean observation cruises were carried out during this period under the Western Equatorial Pacific Ocean Circulation Study (WEPOCS), the United States-People's Republic of China Cooperative Studies (US-PRC), and the World Ocean Circulation Experiment (WOCE) projects with the aim of observing the Pacific LLWBCs [e.g., Lukas et al, 1991;Toole et al, 1990;Kashino et al, 1996]. Through these observations, a zero-order (mean) description of the Pacific LLWBCs was completed [Lukas et al, 1996].…”

Section: Introductionmentioning

confidence: 99%

Ocean variability east of Mindanao: Mooring observations at 7°N, revisited

2015

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Two subsurface moorings were deployed east of Mindanao Island, the Philippines, at 7°01′N, 126°55′E and 7°01′N, 127°46′E, at the location of the inshore and offshore cores of the Mindanao Undercurrent (MUC) suggested by past studies, from September 2011 to October 2012 and March 2013. A steady northward undercurrent, the MUC, was not confirmed by these observations, not only at the location of its inshore core but also of the offshore core. The observed mean flow at the mooring sites seems to be part of an anticyclonic eddy rather than the MUC. A particle‐tracking experiment using a high‐resolution general circulation model output showed that the northward mean flow, called the MUC by past studies, was too weak to advect water to the north. The Mindanao Current during 2011–2012 was weaker than during 1999–2002 because the sea surface height in the Philippine Sea during 2011–2012 was lower than that during 1999–2002. Intraseasonal variability with periods of 50–100 days was observed at the mooring sites, comparable to the previous observations during 1999–2002. Westward signal propagations were observed with periods and speeds of 50 days and 0.20 m s−1 at 300 m depth and of 60–72 days and 0.11–0.14 m s−1 at 960 m depth.

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“…The NEC bifurcates into the northward flowing Kuroshio and the southward flowing Mindanao Current to the east of the Philippines (Toole et al 1990, Qu & Lukas 2003. The southward flowing Mindanao current then flows along the east coast of the southern Philippines before entering the Celebes Sea (Lukas et al 1991).…”

Section: Methodsmentioning

confidence: 99%

Contrasting assemblages of leptocephali in the western Pacific

Minagawa

Miller²,

Aoyama³

et al. 2004

Mar. Ecol. Prog. Ser.

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To learn about the larval distributions and reproductive ecologies of marine and freshwater eels, the assemblages of anguilliform leptocephali were compared between 2 ecologically different areas along the margins of the western Pacific Ocean using the catch data from 2 sampling surveys targeting leptocephali. The assemblages on the outer shelf and slope of the East China Sea in November and December 2000 were dominated by the leptocephali of 2 abundant taxa of congrid and synaphobranchid eels that had been spawning along the shelf break, and by the leptocephali of 3 other families. The leptocephali of many other families were rare, and catch rates were lower over deeper water to the south. In contrast, assemblages of leptocephali were very diverse and showed a widespread presence of most families over the deep water in close proximity to Sulawesi Island in the Indonesian Seas in May 2001, but there were no high catch rates due to the lack of recent spawning activity offshore. As a result, the northern study area had a higher overall catch rate of leptocephali, but much lower richness, diversity, and evenness of taxa than the southern study area in the Indonesian Seas. Cluster analysis distinguished 3 general assemblages that corresponded mostly to each of the 2 study areas and to a group of stations that were mixed between the 2 study areas. This analysis indicates that assemblages of leptocephali can vary widely depending on the location of sampling and on the eel fauna in each particular area.

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Observations of the Mindanao Current during the western equatorial Pacific Ocean circulation study

Cited by 253 publications

References 24 publications

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Ocean variability east of Mindanao: Mooring observations at 7°N, revisited

Contrasting assemblages of leptocephali in the western Pacific

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