Bi-annual intrusion of tropical water in the northern Benguela upwelling

Abstract This study investigates the subduction of South Pacific Tropical Water (SPTW) and its equatorward pathways using a simulated passive tracer of the consortium Estimating the Circulation & Climate of the Ocean (ECCO). The results show that approximately 5.8 Sv (1 Sv ≡ 106 m3 s−1) of the SPTW is formed in the subtropical South Pacific Ocean within the density range between 24.0 and 25.0 kg m−3, of which about 87% is due to vertical pumping and 13% is due to lateral induction, comparing reasonably well with estimates from climatological data. Once subducted, most SPTW spreads in the subtropical South Pacific. Because of the presence of mixing, some portion of the water is transformed, and its tracer-weighted density steadily increases from an initial value of 24.4 to nearly 25.0 kg m−3 after 13 years of integration. Approximately 42% of the water makes its way into the equatorial Pacific, either through the western boundary or interior pathway. The two equatorward pathways are essentially of equal importance. A large (~70%) portion of the SPTW entering the equatorial region resurfaces in the central equatorial Pacific. The potential impacts of the resurfacing SPTW on the equatorial thermocline and surface stratification are discussed.

Download Full-text

A Holocene Marine Climate Record in Mollusc Shells from the Southwest African Coast

Quaternary Research ◽

10.1016/0033-5894(92)90046-l ◽

1992 ◽

Vol 38 (3) ◽

pp. 379-385 ◽

Cited By ~ 67

Author(s):

Anne L. Cohen ◽

John E. Parkington ◽

Geoff B. Brundrit ◽

Nikolaas J. van der Merwe

Keyword(s):

Late Quaternary ◽

Climatic Variability ◽

Temperature Changes ◽

Climate Record ◽

Benguela Upwelling ◽

Isotope Record ◽

History Of ◽

Glacial Expansion ◽

Sediment Layers ◽

Marine Climate

AbstractDetails of short-term climatic variability are often lost from marine sediments through bioturbation in the upper, aerobic sediment layers. Alternatively, a high-resolution and dated record of climatic events may be obtained using material preserved in archaeological deposits. The Holocene history of the southern Benguela upwelling regime has been constructed from the oxygen isotope and mineral analysis of midden shells. Three discrete episodes of significant isotope enrichment corresponded to periods of glacial expansion in the northern hemisphere. Significant changes in shell mineralogy, which is a response to sea-surface temperatures, were also recorded. The timing and duration of these changes approximated those in the isotope record and may provide a link between events affecting the subcontinent and global temperature changes of the late Quaternary.

Download Full-text

Microphytoplankton structure from the neritic and oceanic regions of Pernambuco State - Brazil

Brazilian Journal of Biology ◽

10.1590/s1519-69842009000500007 ◽

2009 ◽

Vol 69 (4) ◽

pp. 1037-1046 ◽

Cited By ~ 7

Author(s):

ML. Koening ◽

BE. Wanderley ◽

SJ. Macedo

Keyword(s):

Principal Component ◽

Mesh Size ◽

Species Number ◽

Phytoplankton Diversity ◽

Trichodesmium Erythraeum ◽

Species Association ◽

Tropical Water ◽

Key Species ◽

Distribution And Ecology ◽

Planktonic Species

This research was carried out to assess phytoplankton diversity, distribution and ecology on the Pernambuco Continental Shelf and Oceanic region (lat. 7º 33' 00" S to 8º 41' 50" S and long. 34º 04' 47" W to 35º 01' 20" W). Samples were collected during the Joint Oceanographics Projects (JOPS II-Leg 5) by double oblique hauls with a baby bongo net 64 µm mesh size at depth between 14 and 150 m in inshore and offshore waters respectively, in seven transects, totaling 34 stations. The temperature and salinity characterised the tropical water masses. The dissolved oxygen was oversaturated in all stations. The nutrient-low concentrations showed an oligothrophic pattern in the whole area. 173 specific and infraspecific taxa were identified: Dinophyta (103 taxa), Bacillariophyta (61 taxa), Cyanobacteria (7 taxa), Chlorophyta and Chrysophyta (1 taxon). The family Ceratiaceae presented the highest species number (47 taxa). The cyanobacteria Trichodesmium erythraeum Ehrenberg, Oscillatoria spp. and the diatom Leptocylindrus danicus Cleve had higher frequence of occurrence and abundance. Species diversity varied from 0.71 to 3.46 bits.cell-1 and this low index was due to Trichodesmium erythraeum bloom and evenness from 0.14 to 0.65, showing an unstable pattern. The oceanic planktonic species were responsible for the higher richness with 78 taxa, corresponding to 58.39% of the total microphytoplankton. The species association presented two groups. The first one divided in two subgroups: one associated to the neritic/oceanic and oceanic planktonic species and the other to the oligotrophic indicator species. The second group was composed of some key species which were the most abundant and frequent in the area. The first three Principal Component Analyses (PCAs) explained 50.91% of the data variance showing that the area is structured by two groups: one offshore composed by oligotrophic indicators, and another nearshore influenced by continental fluxes.

Download Full-text

Seasonal and interannual phytoplankton dynamics and forcing mechanisms in the Northern Benguela upwelling system

Journal of Marine Systems ◽

10.1016/j.jmarsys.2016.01.009 ◽

2016 ◽

Vol 157 ◽

pp. 124-134 ◽

Cited By ~ 21

Author(s):

Deon C. Louw ◽

Anja K. van der Plas ◽

Volker Mohrholz ◽

Norbert Wasmund ◽

Tim Junker ◽

...

Keyword(s):

Phytoplankton Dynamics ◽

Upwelling System ◽

Benguela Upwelling ◽

Forcing Mechanisms

Download Full-text

Sea surface temperature variability in the northern Benguela upwelling system, and implications for fisheries research

International Journal of Remote Sensing ◽

10.1080/014311600209922 ◽

2000 ◽

Vol 21 (8) ◽

pp. 1597-1617 ◽

Cited By ~ 17

Author(s):

J. Cole ◽

C. Villacastin

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Temperature Variability ◽

Sea Surface ◽

Upwelling System ◽

Benguela Upwelling

Download Full-text

Molecular breeding of water lily: engineering cold stress tolerance into tropical water lily

Horticulture Research ◽

10.1038/s41438-018-0086-2 ◽

2018 ◽

Vol 5 (1) ◽

Cited By ~ 4

Author(s):

Cuiwei Yu ◽

Guirong Qiao ◽

Wenmin Qiu ◽

Dongbei Yu ◽

Shirong Zhou ◽

...

Keyword(s):

Cold Stress ◽

Stress Tolerance ◽

Molecular Breeding ◽

Water Lily ◽

Tropical Water

Download Full-text

Distribution and annual occurrence of Chaetognatha off Cananeia and Santos coast (São Paulo, Brazil)

Boletim do Instituto Oceanográfico ◽

10.1590/s0373-55241968000100003 ◽

1968 ◽

Vol 17 (1) ◽

pp. 33-55 ◽

Cited By ~ 7

Author(s):

M. S. de Almeida Prado

Keyword(s):

Coastal Water ◽

Annual Variation ◽

Abundant Species ◽

Breeding Period ◽

Shelf Water ◽

Vertical Movements ◽

Tropical Water ◽

The Vertical Distribution ◽

Water Species ◽

Different Levels

Plankton samples were fortnightly taken at three fixed stations off Cananéia (1958, 1959, 1960) and off Santos (1960, 1961) by vertical hauling. They contained the following species: Sagitta enflata, S. friderici, S. hispida, S. minima, S. serratodentata, Krohnitta pacifica and Pterosagitta draco. S. frideriei is a typical coastal water species. S. enflata is a typical shelf water species. S. hispida and K. pacifica were present more frequently in shelf water but they were sometimes very abundant in coastal water. S. serratodentata, S. minima and P. draco occurred sparingly in tropical water, however, very few samples were taken in this water mass. Three different maturity stages were established (juvenile, intermediate and adult) in order to study the annual variation of the Chaetognatha. A special breeding period throughout the year was not observed as great swarms of juveniles and intermediates were found in spite of the very small number of adults. Two series of samples taken off Santos at a fixed station (Pt. III) during a period of 24 hours in three different levels were also counted to study the vertical distribution of the Chaetognatha in this area. The three most abundant species were: S. enflata, S. hispida and K. pacifica. S. enflata was more frequent at mid-water. S. hispida and K. pacifica seemed to prefer the surface layer. The thermocline did not affect their vertical migration except for S. hispida. There is indication that S. serratodentata performs vertical movements. S. minima seems to live below 25 m depth. K. subtilis occurred exceptionally in this vertical series of samples.

Download Full-text