1,721,040 research outputs found
RRS Discovery Cruise 351, 10-28 May 2010. The Extended Ellett Line 2010.
Full text linkThe Extended Ellett Line is a full-depth hydrographic section between Iceland, 60°N 20°W, Rockall and Scotland. The original Ellett Line across the Rockall Trough was first occupied in 1975 when measurements were attempted four times a year. In 1996 the line was extended to Iceland and occupied approximately annually. The data form a 35 year time-series of the oceanic conditions west of the British Isles.The section monitors the characteristics of the warm water inflow into the Nordic Seas and thence to the Arctic, and observes part of the returning cold water outflow with measurements of the Iceland-Scotland Overflow and the overflow of the Wyville-Thomson Ridge into the Rockall Trough.The 2010 occupation, RRS Discovery Cruise 351, was completed successfully with 48 CTD stations worked between the Iceland and Scotland shelf edges. Additionally, Line G, part of the SAMS observation network of the Scottish continental shelf was completed. Samples were taken for inorganic nutrients, iron and trace metals, bioluminescence and microscope analysis. Incubation experiments were performed to investigate the role of microzooplankton grazing and the speciation of iron, and to investigate the presence of dinoflagellate bioluminescence.In addition to the planned programme, sampling took place to investigate the extent of the fall out from the ash plume emitted by the Iceland volcano, Ejyafjallajokull, and its impact on the biogeochemistry and productivity of the upper ocean.A trial tow of SeaSoar and a short survey of the upper ocean over the Anton Dohrn seamount were successfully completed
RRS Discovery Cruise 213, 06 Jan-21 Feb 1995. South West Indian Ocean Experiment (SWINDEX)
Full text linkRRS Discovery Cruise 201, 23 Mar-03 May 1993. South West Indian Ocean Experiment (SWINDEX)
Full text linkRV "Poseidon" Cruise 314, 11 Jul - 23 Jul 2004. The 'Extended Ellett Line’, Scotland - Rockall - Iceland time series
Full text linkThis report describes R/V Poseidon Cruise 314, designed to repeat the hydrographic section from Scotland to Rockall, called the Ellett Line, and its extension to Iceland.73 stations were worked with CTD and lowered ADCP and sampled for chemical (macronutrients and dissolved oxygen) and biological (chlorophyll a) analyses. Additional samples for analysis of dissolved iron, pigments and plankton physiology were taken at a few selected sites. Underway measurements of depth, meteorology, surface water properties and currents were made. The weather during the cruise was good, with no time lost to the elements and more than the expected number of stations worked. Conversely data logging and processing suffered from so many problems that it was not possible to edit and calibrate the data during the cruise
Large-scale circulation around the Crozet Plateau controls an annual phytoplankton bloom in the Crozet Basin
No full textThe circulation in the vicinity of the Crozet Plateau in the Southwest Indian Ocean sector of the Southern Ocean is examined using hydrographic sections, Argo floats, surface drifters, and satellite altimetry. All four techniques confirm that a major branch of the Antarctic Circumpolar Current, the SubAntarctic Front (SAF), flows anticyclonically round the Del Caño Rise west of the Crozet Plateau, i.e. eastward to the south of the Del Caño Rise, then northward and sometimes northwestward into the Crozet Basin, before turning back eastward in a combined front with the Agulhas Return Current and the SubTropical Front. This S-bend in the SAF is a permanent feature, controlled by the bathymetry, as has been inferred previously by Pollard and Read [Pollard, R.T., Read, J.F., 2001. Circulation pathways and transports of the Southern Ocean in the vicinity of the Southwest Indian Ridge. Journal of Geophysical Research, 106(C2), 2881–2898]. Similar, but much weaker, anticyclonic flow is found round the Crozet Plateau itself, with no more than 5?10×106 m3 s?1 turning north to the east of the Crozet Islands. Circulation north of the Crozet Plateau, between the Plateau and the S-bend of the SAF, is extremely weak, fed only by anticyclonic meanders breaking off the SAF into the area from the west or north, and occasional input from the northward, partially wind-driven (i.e. Ekman) flow south and east of the islands. In consequence of the weak circulation, dissolved iron from the land or sediments of the Crozet Plateau and Islands can build up during the winter in the Polar Frontal Zone between Crozet and the SAF, which gives rise to an annual bloom in this area. Biological evidence from satellite images, and from phytoplankton and zooplankton distributions, supports the circulation pattern we develop. This pattern confirms that patchiness of productivity in the bloom area results from close juxtaposition of water that has entered the area from the west from the SAF and from the south and east after flowing past the islands. Flow from the south and east has had a chance to entrain iron from the islands and sediments whereas flow from the west has not
RRS Discovery Cruise 365, 11 May-02 Jun 2011. The Extended Ellett Line 2011
Full text linkThe Extended Ellett Line is a full-depth hydrographic section between Iceland, 60°N 20°W, Rockall and Scotland. The original Ellett Line across the Rockall Trough was first occupied in 1975 when measurements were attempted four times a year. In 1996 the line was extended to Iceland and since then has been occupied approximately annually. The data form a 35 year time series of the oceanic conditions west of the British Isles.The section monitors the characteristics of the warm water inflow into the Nordic Seas and thence to the Arctic, and observes part of the returning cold water outflow with easurements of the Iceland-Scotland Overflow and the overflow of the Wyville-Thomson Ridge into the Rockall Trough.The 2011 occupation, RRS Discovery cruise 365, was curtailed by both technical problems and bad weather. 45 of the 48 CTD stations were worked between the Iceland and Scotland shelf edges. Line G, part of the SAMS observation network of the Scottish continental shelf was partially completed, with 4 stations at the western end not worked. Samples were taken for CFC and SF6 analysis, DIC and alkalinity, inorganic nutrients, aluminium, POC, bacterial abundance and biomass, and for phytoplankton community structure. Plans to repeat stations, to collect validation data for the SAMS glider and to investigate eddies in the Rockall Trough had to be abandoned
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