4,531 research outputs found
RRS Discovery Cruise 321, 24 Jul-23 Aug 2007. Biophysical interactions in the Iceland Basin 2007
No full textD321 was the first of three National Oceanography Centre ‘process study’ research cruises to be run by the Ocean Biogeochemistry and Ecosystems research group under the NERC Oceans 2025 research programme. The scientific work began by carrying out some of the extended Ellett Line stations on the way out to our study region; which centred around the historical JGOFS Ocean Weather Station India site (~ 59° N, ~ 19° W) and the northward turn of the extended Ellett line at 20° W. The Iceland Basin, like much of the N. Atlantic subpolar gyre, is characterised by a ‘bloom and bust’ seasonal cycle. Spring stratification triggers a major diatom dominated bloom event. This bloom is short lived, limited by silicate (orthosilicic acid) exhaustion (Brown et al., 2003). Two community succession pathways commonly follow the demise of the diatom bloom; typically through dinoflagellate and/or coccolithophore production. The spring bloom is dominated by eddy scale (several 10's of km) patchiness, driven by the upward and downward pumping effect of eddies on the newly forming spring stratification. However these eddy structures have another, more important, impact on phytoplankton production (Allen et al., 2005). In the release of potential energy, eddies effect a real three dimensional exchange of water across the thermocline bringing new dissolved nutrients from deeper waters up into the photic zone and transporting biogenic particles into the deep ocean. Thin ribbon like structures around the edges of eddies are clearly seen in ocean colour satellite images. The four repeated surveys carried out during D321 observed the evolution of an ‘eddy dipole’ in a background ocean full of eddies and other turbulent motions. Daily, near real-time, satellite images and in-situ vessel mounted acoustic current profiling were used to determine the movement of the eddy centres and the dipole central jet. Targeted nets and water collection within the various components of the eddy dipole enabled the assessment of its biological impacts.Since 1996 NOCS and SAMS have been occupying an extended version of the Ellett Line that runs all the way to Iceland. The Extended Ellett line is important oceanographically because it completes the measurements of the warm saline water flowing into the Nordic Seas from the eastern North Atlantic. It also monitors around half of the returning deep and cold current, the overflow water (the rest returns to the Atlantic via the Denmark Strait to the west of Iceland).There is little added cost, either in time or financially, in making a number of biogeochemical measurements using water samples from the hydrographers' CTD stations. Thus, recently, the scientific interests in the Extended Ellett line have become more multidisciplinary; the 2006 occupation was no exception. Samples were filtered for POC, HPLC studies and trace aluminium concentration determination, in addition some extra time was found for a number of zooplankton net hauls.<br/
RRS Discovery Cruise 253, 04 May-20 Jun 2001. Faeroes, Iceland, Scotland Hydrographic and Environmental Survey (FISHES)
No full textThe FISHES 2001 cruise, RRS Discovery Cruise 253, was split into two legs. A large scale CTD survey of the Iceland Basin and Rockall Trough was carried out during the first and longer leg, 4 May – 21 May. The second leg, 1 June – 20 June, concentrated on repeated high resolution SeaSoar surveys of the Iceland Faeroes Front (IFF). A wide range of measurements were made alongside each scale of physical survey techniques used for the two legs of the cruise. These ranged from traditional biological sampling using net hauls to fast repetition fluorometric techniques for the underway determination of primary productivity parameters. Deck phytoplankton incubation experiments under controlled light environments involved both the usual measurements of N15 uptake and measurements of Si32 uptake. During the second leg of the cruise, a regional multi-disciplinary process model was used to forecast observations in near real-time
GC-FID data of biocatalytic esterification reactions & NMR data of lignin characterization
No full textTabulated chromatographic data (GC-FID) from butyl butyrate esterification reactions. 13C and 31P NMR data from pine kraft lignin (BIOPIVA 100) and cationic pine kraft lignin. A list of sample code identifiers with their descriptions is available upon request from the author.<br
RRS Discovery Cruise 312, 11-31 Oct 2006. The extended Ellett Line 2006
No full textUK oceanographers have been making repeated measurements on a short section across the Rockall Trough, since 1975. The section consists of a series of stations from the Scottish continental shelf to Rockall. The time series was established by David Ellett and was thus called the "Ellett Line". The Ellett line is one of a relatively small number of high quality physical time series in the North Atlantic Ocean and is important for monitoring oceanic climate variability.Since 1996 NOCS and SAMS have been occupying an extended version of the Ellett Line that runs all the way to Iceland. The Extended Ellett line is important oceanographically because it completes the measurements of the warm saline water flowing into the Nordic Seas from the eastern North Atlantic. It also monitors around half of the returning deep and cold current, the overflow water (the rest returns to the Atlantic via the Denmark Strait to the west of Iceland).There is little added cost, either in time or financially, in making a number of biogeochemical measurements using water samples from the hydrographers' CTD stations. Thus, recently, the scientific interests in the Extended Ellett line have become more multidisciplinary; the 2006 occupation was no exception. Samples were filtered for POC, HPLC studies and trace aluminium concentration determination, in addition some extra time was found for a number of zooplankton net hauls.<br/
Macro-, micro- and nano-investigations on 3-aminopropyltrimethoxysilane self-assembly-monolayers
No full textRRS Discovery Cruise 381, 28 Aug - 03 Oct 2012. Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS)
No full textCruise D381 was made in support of NERC's Ocean Surface Boundary Layer theme action programme, OSMOSIS (Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study). The ocean surface boundary layer (OSBL) deepens in response to convective, wind and surface wave forcing, which produce three-dimensional turbulence that entrains denser water, deepening the layer. The OSBL shoals in response to solar heating and to mesoscale and sub-mesoscale motions that adjust lateral buoyancy gradients into vertical stratification. Recent and ongoing work is revolutionising our view of both the deepening and shoaling processes: new processes are coming into focus that are not currently recognised in model parameterisation schemes. In OSMOSIS we have a project which integrates observations, modelling studies and parameterisation development to deliver a step change in modelling of the OSBL. The OSMOSIS overall aim is to develop new, physically based and observationally supported, parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions. Cruise D381 was split into two legs D381A and a process study cruise D381B. D381A partly deployed the OSMOSIS mooring array and two gliders for long term observations near the Porcupine Abyssal Plain Observatory. D381B firstly completed mooring and glider deployment work begun during the preceding D381A cruise. D381B then carried out several days of targetted turbulence profiling looking at changes in turbulent energy dissipation resulting from the interation of upper ocean fluid structures such as eddies, sub-mesoscale filaments and Langmuir cells with surface wind and current shear. Finally D381B conducted two spatial surveys with the towed SeaSoar vehicle to map and diagnose the mesoscale and sub-mesoscale flows, which, unusually, are the `large scale' background in which this study sits
Bodem- en Oeverbescherming met GC\u92s: Pilotproject \u93Taludbescherming\u94
No full textMet een mat van GC\u92s wordt waterstroming geremd en zand vastgehouden. Dit biedt allerlei mogelijkheden voor de waterbouw. In deze proef zijn eerst schaaltesten in laboratoriumomstandigheden verricht waarmee aannemelijk gemaakt werd dat een talud beschermd kan worden tegen erosie van de ondergrond door golfslag door middel van een afdekking van GC\u92s. Zowel de technische als de financiële haalbaarheid is bekeken en als positief beoordeeld. In een daarop volgende grotere proef (pilotproject) is een testvak op de maasvlakte gebouwd en voor ruim een jaar gemonitord. Inderdaad houdt een GC mat op de vooroever (1:6 talud) zand vast, en dat gehele pakket beschermt de daaronder liggende laag tegen erosie, met resultaten die vergelijkbaar zijn met een traditionele bestorting van 40-60 Kg stortsteen. Tenslotte zijn de grenzen verkend. In 2 experimenten is de mat zeer zwaar belast om te onderzoeken tot welke condities deze stabiel is. Deze stabiliteitsgrenzen blijken ver weg te liggen, en verrassend goed in lijn te zijn met voorspellingen uit de schaaltesten. Samengevat kan gesteld worden dat de GC voor bodem- en oeverbescherming een interessante innovatie is. Een talud kan beschermd worden tegen erosie. We zijn nu redelijk in staat aan te geven wat voor soort mat met welke GC\u92s nodig is bij bepaalde condities. Indien cradle-to-cradle biocomposieten gebruikt worden ontstaat een duurzame oplossing. Daarop voortbouwend lijkt het erop dat dit experiment nu al een waaier van verdere toepassingen opent. In biodegradeerbare varianten kunnen tijdelijke constructies gebouwd worden, bijvoorbeeld om jonge aanplant op gang te helpen in een omgeving met stroming of begrazing (\u93Bshore\u94). Ook in de vorm van vooroeverdam (kunstrif) liggen kansen, waarbij lessen uit dit experiment waardevol zijn. Wij zien dit ITC project als een goed voorbeeld van hoe in samenwerkingsverbanden Rijkswaterstaat, kennisinstituten en bedrijfsleven gezamenlijk onderzoek en experimenten kunnen verrichten, op een uiterst aangename en constructieve manier, tot voordeel van allen
Scheherezade - an interdisciplinary study of the Gulf of Oman, Strait of Hormuz and the southern Arabian Gulf, Charles Darwin Cruise 104, 12 Feb-30 Apr 1997. No. 13. Calibrated multifrequency target strength data from the EK500.. Leg 1, 12 Feb - 19 March
No full textRRS Discovery Cruise 224, Leg 1, 27 Nov-29 Dec 1996. OMEGA: Observations and Modelling of Eddy scale Geostrophic and Ageostrophic motion. Physical and biological observations in the eastern Alboran Sea (western Mediterranean)
No full textThe first leg of RRS Discovery Cruise 224, 27/11/96 - 29/12/96, was one of two cruise programs designed to provide the experimental field observations for the EU MAST 3 project, OMEGA (Observations and Modelling of Eddy scale Geostrophic and Ageostrophic motion). Towing the undulating CTD vehicle, SeaSoar, two large scale and three fine scale SeaSoar surveys were made of the Almeria-Oran front region of the western Mediterranean. In addition a brief SeaSoar survey was made of the head of the Algerian Current. These hydrographic measurements of the upper 370 metres of the water column were accompanied by VM-ADCP and ACCP derived ocean currents, underway physical, chemical and biological analysis of surface water samples, multi-frequency acoustic backscatter measurements, meteorological observations and sea surface radiation measurements. Between the surveys, CTD stations were accompanied by detailed measurements of ocean optical properties at strategic locations along and across the front. In addition 8 towed deployments of a Longhurst Hardy Plankton Recorder were made to look at the change in plankton species composition across frontal zones
Eddy transport of Western Mediterranean Intermediate Water to the Alboran Sea
No full textDuring the second cruise of the EU funded OMEGA project the towed undulating vehicle SeaSoar, was deployed to survey the upper 350 m of the water column in the eastern Alboran Sea and extreme western Algerian basin. With an effective along-track resolution of 4 km, the data sets enabled a detailed description of the different upper ocean water types and the fronts that separate them. The Almeria Oran front forms at the eastern boundary of the Alboran Sea gyre system, in the upper 150–200 m of the water column, and separates waters of predominantly Atlantic origin from those formed in the Western Mediterranean Sea. Below these surface waters, but above the Levantine Intermediate Water, Western Mediterranean Intermediate Waters, believed to be formed to the north of the Balearic Sea, are normally observed in this region. However, to our knowledge, this is the first time a discrete eddy of Western Mediterranean Intermediate Water, a “weddy,” has been described in the extreme western Algerian basin. Repeated surveys of the region allowed us to observe the evolution of the eddy over a period of 40 d. A climatological analysis of historical data in the MEDAR/MEDATLAS database provides evidence for the repeatability of this observation and the significance of the estimated transport
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