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LOMROG III expedition in 2012 with the Swedish icebreaker Oden

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Field reports from the LOMROG III cruise

LOMROG III cruise report

The LOMROG III cruise report describes in detail the various projects carried out during the cruise
Download the report a76.dk/xpdf/lomrog-III_cruise-report.pdf pdf-file, ~13mb.
 

LOMROG III – Results

Chief scientist Christian Marcussen ( ), GEUS

The LOMROG III cruise aboard the icebreaker Oden was organized by the the Continental Shelf Project of the Kingdom of Denmark in cooperation with the Swedish Polar Research Secretariat and costs were split between Denmark (80%) and Sweden (20%). This cruise was a continuation of the LOMROG I and II cruises, which took place in 2007 and 2009, respectively. LOMROG is an acronym for Lomonosov Ridge off Greenland.

The main objectives were:

  1. to acquire bathymetric data on the flank of the Lomono­sov Ridge facing the Amundsen Basin, supported by con­ductivity, temperature, and depth (CTD) casts taken from both Oden and the sea ice
  2. to acquire single-beam spot soundings obtained using Oden's helicopter to supplement the multibeam data,
  3. to acquire seismic data in the Amundsen Basin and on the Lomonosov Ridge,
  4. to acquire gravity data along Oden's track,
  5. to dredge along the flank of the Lomonosov Ridge facing the Amundsen Basin,
  6. to support other Danish research projects,
  7. to support Swedish research projects (read more about the Swedish projects (pdf-file, ~5mb) ).

The LOMROG III cruise started on 31 July 2012 in Longyear­byen, Svalbard, where it also ended on 14 September 2012.

Bathymetric map

Bathymetric map (IBCAO 3.0 ) showing the LOMROG III ship track (orange) and fieldwork north of Greenland as part of the Continental Shelf Project of the Kingdom of Denmark from 2006 to 2012. Green line – LOMROG I ship track (2007), red line – LOMROG II ship track (2009), light blue lines – bathymetric profiles acquired by helicopter in spring 2009 and during LOMROG II and III (2009 and 2012), yellow lines – seismic lines acquired during LORITA (2006 – refraction) & LOMROG I and II (2007, 2009 & 2012 – reflection and refraction), red crosses – dredging sites, and white stippled lines – unofficial median lines. Enlarge.
 

By agreement with the Norwegian Fram 2012 expedition led by Yngve Kristoffersen, University of Bergen, Oden pro­vided fuel and other supplies to the expedition’s hovercraft Sabvabaa twice during the LOMROG III cruise. One member of the Fram 2012 expedition boarded Oden on the way back to Longyearbyen on Svalbard.

Refuelling of the Fram 2012 expedition’s hovercraft Sabvabaa
 

Refuelling of the Fram 2012 expedition’s hovercraft Sabvabaa at the first rendezvous August 3, 2012 (Photo: Björn Eriksson)
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The many results of the LOMROG III cruise could not have been obtained without the excellent cooperation between the crew of Oden, the helicopter crew, and the science party. The cooperation between the various science groups made it possible to make very efficient use of the resources on board Oden and provided by the helicopter.

LOMROG III was the last cruise to the area north of Greenland as part of the Continental Shelf Project of the Kingdom of Denmark and therefore represents the end of the very successful cooperation between the Geological Survey of Denmark and Greenland (GEUS) and the Swedish Polar Research Secretariat . It is hoped that the valuable experience gained during the three LOMROG cruises (in 2007, 2009, and 2012) and the EAGER cruise (2011) can be useful for future cruises of Oden to the Arctic Ocean.
 

Bathymetric data acquisition

Richard Pedersen ( ) and Morten Sølvsten ( ), Danish Geodata Agency

Oden is equipped with a multibeam echo sounder and a chirp sonar (sub-bottom pro­filer). During the LOMROG III cruise, Oden travelled a total of 3672 nautical miles. Multi­beam bathymetric data as well as sub-bottom pro­filer data were recorded continuously along the ship’s track.

The “pirouette method” was developed during the LOMROG I cruise. In this method, Oden would stop and spin 360°C in isolated pools of open water while sweeping the sea­bed with the multibeam sounder. This meth­od was also used during LOMROG III, though at critical locations Oden had to break a lead in the ice before a pirouette was possible.

The bathymetric data acquired during the LOMROG III cruise will be integrated into a new version of the International Bathymetric Chart of the Arctic Ocean (IBCAO) .

Overview map showing the main part of the bathymetric data acquired during LOMROG III

Overview map showing the main part of the bathymetric data acquired during LOMROG III. Numbers indicate the four profiles covering the flank of the Lomonosov Ridge facing the Amundsen Basin. Data acquisition (profiles 1 and 2) was focused on the data gap between data acquired during LOMROG I, spot soundings during LOMBAG 2009 and data acquired during LOMROG II.
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Seismic data acquisition

Thomas Funck ( ), John R. Hopper ( ), GEUS; Per Trinhammer ( ), Department of Geoscience, Aarhus University and Thomas Varming ( ), Greenland Bureau of Minerals and Petroleum

Acquisition of seismic data in the Amundsen Basin and on the Eastern flanks of the Lomonosov Ridge was the second priority of the LOMROG III cruise. Harsh environmental conditions in the Arctic have been a crucial consideration when designing the seismic equipment and modifying the setup. These modifications were based on previous experience with seismic data acquisition in ice-filled waters as well as on the two previous LOMROG expeditions (more details).

Oden collecting seismic data along a prepared track in the Amundsen Basin

Oden collecting seismic data along a prepared track in the Amundsen Basin (Photo: Thomas Funck).
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During the LOMROG III cruise, a total of 498 km of seismic data were acquired. Furthermore, 63 sonobuoys were deployed of which 59 were transmitting data back to the ship.

Seismic reflection line acquired in the Amundsen Basin showing the overall good data quality.

Seismic reflection line acquired in the Amundsen Basin showing the overall good data quality.
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The seismic data acquired during the three LOMROG cruises will form an important part of the documentation of a Kingdom of Denmark submission regarding an extended continental shelf in the area north of Greenland, due at the end of 2014.
 

Gravimetric data acquisition

Indriði Einarsson ( from DTU Space

Ocean gravity data reflect the bathymetry and density distribution of the oceanic crust and mantle. Low gravity values are related to low densities (sediments), submarine canyons or trenches. High gravity values are related to high densities, seamounts and ocean ridges. Coincident measurements of gravity and water depth make it possible to remove the bathymetric contribution from the gravity signal by assuming that the crust has constant density. This isolates the non-bathymetric signal, indicating density variations below the seabed that can be used in estimating sediment thickness.

Marine gravimeter (left) - gravity measurement on sea ice (right)

(Left) Marine gravimeter in the pump room on board Oden (Photo: Indriði Einarsson). (Right) Indriði Einarsson conducting a gravity measurement on sea ice (Photo: Thomas Varming).
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Gravity data were collected continuously during LOMROG III with the gravimeter installed on board Oden, supplemented by 77 gravity readings on the ice using a land gravimeter. Oden again provided an excellent platform for marine gravity measurements and the gravimetric data collected will be useful for the Continental Shelf Project and make an important new data contribution to the Arctic Gravity Project.
 

Dredging

Christian Marcussen ( ), GEUS; Jack Schilling, NIOZ and Per Trinhammer ( ), Department of Geoscience, Aarhus University

Rock samples dredged from the Lomonosov Ridge could yield valuable information on the origin of the ridge and could strengthen the argument for a natural prolongation of the Canadian–Greenland Shelf onto the ridge.

On 19 and 20 August 2012 two dredges were undertaken, both by moving Oden up the slope of the Lomonosov Ridge using the ice drift. Dredging took place from water depths of 3500 m to 2500 m. The first dredge gathered approximately 100 kg of rock samples and the second approximately 200 kg. Based on a preliminary visual inspection, most of the rock samples are believed to be from an outcrop. Nearly all samples appear to be covered by some kind of ferromanganese crust. Only a few dropstones were found.

Retrieval of dredge 2 and some examples of the rock samples gathered.

Retrieval of dredge 2 and some examples of the rock samples gathered. The photo in the lower right shows a large rock (“LOMROCK”) sampled during dredge 2 (Photos: Thomas Funck and Christian Marcussen).
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Oceanography: CTD measurements

Steffen M. Olsen ( ) and Rasmus Tonboe ( ), Centre for Ocean and Ice, Danish Meteorological Institute

The oceanographic programme carried out during the LOMROG III cruise included the collection of water column profiles with conductivity, temperature, and depth (CTD) data. In addition, discrete water samples were collected at specific depths. From CTD measurements the vertical salinity, density and sound v to support operationally the seismic and hydrographic data acquisition of the Continental Shelf Project wi to support the Danish and Swedish research projects onboard Oden oceanographic data, water sample collection and guidance.

The task was successfully completed with collection of CTD profiles at 42 localities along the cruise track. Of these, 29 were ice-stations were acquired using a portable modular equipment capable of reaching depths down to 2000m. This system was mobilized via Oden's helicopter and completed within four hours on the ice at each station with no use of ship time. The logistics allowed a Swedish marine biological research project depending on the local oceanographic measurements to be coupled to the program on the ice.

In addition, 13 ship stations were completed with full-depth CTD profiles also covering the lowermost and less variable part of the water column (below 4000m). Ship stations made use of a CTD system mounted in a 24 bottle rosette water-sampler operated from the bow of Oden. A number of science projects exploited this opportunity to collect water samples at well-defined layers and were involved in the station sample planning requiring coordination across science groups. In a limited number of cases CTD profiles were collected with more simple, expendable probes with real time data logging (read more about a similar project during LOMROG II in 2009).

Oceanographic data collected by DMI researchers during the LOMROG III expedition are integrated in a number of scientific research projects of DMI. In particular, data are important for investigations focused on the upper ocean halocline structure of the Arctic Ocean. The halocline is a unique feature of the Arctic Oceans stratification, which strongly restrains the exchange of heat between the cold, upper mixed-layer below the sea ice and the warm core of Atlantic water found at 300-500m depth. In order to address the often complex composition of this layer, additional sensors were added to the standard CTD program and bottle samples for biogeochemical tracers at prescribed depths were collected. The tracer set for post cruise analysis includes approximately 300 discrete samples from which the oxygen isotopic composition, inorganic nutrients and dissolved organic matter will be analysed.

CTD station map showing ship (S), expendable probes (X) and helicopter (H) ice stations recovered during LOMROG III

CTD station map showing ship (S), expendable probes (X) and helicopter (H) ice stations recovered during LOMROG III.
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Danish Science of Opportunity Projects

Structuring of the sea ice environment by dynamic ice-algae activity

Lars Chresten Lund-Hansen ( ) and Brian Sorrell ( ), Department of Bioscience , Aarhus University in cooperation with Hans Ramløv, Roskilde University and Søren Rysgaard, Greenland Institute of Natural Resources

The contribution of ice algae to the global environment is difficult to estimate, but they may be responsible for up to 5% of all photosynthesis and gradients in algal biomass and adaptatio the transmission and attenuation of light through the snow-ice column and how this is related to variatio what the spatial distribution of algae in sea ice in relation to ice structure and antifreeze protein production.

Ice cores and seawater were collected daily from 2 August to 11 September 2012 (more details ).

Bottom surface of ice core

(Left) Bottom surface of ice core with visible patches of algae. The lower 2 cm of an ice core has been sectioned from the core and mounted bottom upwards in the circular frame used to position it for imaging. (Right) Fluorescence imaging set-up (left) with the Imaging-PAM Fluorometer. The principle of the method is that algae emit (fluoresce) red light into the camera when irradiated with blue light from the light source. Images were taken of the bottom surface of the ice, as shown in this diagram, or of cross-sections through the ice core section. The apparatus is enclosed in a light-proof box (right) to protect the core section from sunlight and ensure low light intensities relevant for sea ice throughout measurements (Photo: Lars Chresten Lund-Hansen).
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Characterization of bioactive gram-positive spore-forming Arctic bacteria

Nikolaj Grønnegaard Vynne ( ) in cooperation with Lone Gram ( ), DTU Systems Biology

The aim of this project was to collect samples from hitherto underexplored areas in the Arctic Ocean, focusing on novel gram-positive spore-forming bacteria. The bioactive potential of these bacteria will be investigated, with a focus on antibiosis.

On board the icebreaker Oden, samples were taken from sediment, dredged mud, ice cores, and the water column. A total of 143 samples were obtained, 23 of which were collected as part of a Swedish research project (more details ).

The collected samples will be analysed at the National Food Institute, Technical University of Denmark, with a focus on long-term incubation and substrate influence on bacterial culturability. Results will be published as a scientific article in a peer-reviewed microbiology journal.

Use of motorised Kovacs ice corer (left) - Arctic sediment samples (right)

(Left) Use of motorised Kovacs ice corer to collect ice cores (Photo: Markus Karasti). (Right) Arctic sediment samples inoculated on nutrient poor growth substrate (Photo: Nikolaj Grønnegaard Vynne).
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Sea ice temperature project

Gorm Dybkjær ( )and Rasmus Tonboe ( ), Centre for Ocean and Ice, Danish Meteorological Institute

The aim of the sea ice temperature project conducted during the cruise was to collect a large dataset capturing the influence of and correlation between actual snow and ice temperatures, satellite measurements, and the variables that influence these measurements. This will provide valuable knowledge for both thermodynamic modelling and algorithm development in remote sensing-based applications. Data were acquired using infrared and microwave instruments installed on Oden (see figure 11), eight mass balance buoys deployed between Greenland and the North Pole and in situ measurements of snow and ice characteristics recorded throughout the cruise (more details).

The synchronous measurements of sea ice temperature will be compiled in a match-up database after the expedition. The subsequent data analysis will improve our understanding of snow and sea ice temperatures and of the melting/freezing processes in the Arctic. New insight into Arctic snow and ice properties will improve the interpretation of satellite-based temperature measurements and eventually result in higher-quality temperature data input to ocean and weather models.

Oden seen from helicopter and Sea ice mass balance buoy number 4

(Left) Oden seen from helicopter. On Monkey Island above the Bridge, Infra-Red and Microwave instruments are placed to measure sea ice temperatures (red arrow) (Photo: Gorm Dybkjær). (Right) Sea ice mass balance buoy number 4 deployed on August 14, at position 88.35N 30.77W. The yellow box contains data logger, satellite communication and battery pack. The white stick holds the top of the thermistor string above the snow/ice surface, so that the temperature profile is measured from approximately 0.5m above the surface and down through the snow, ice and water (Photo: Gorm Dybkjær).
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Other Danish activities - Media crew on board Oden during LOMROG III

Martin Breum ( , website: www.martinbreum.dk), Danish Broadcasting Corporation DR2 and Kenneth Sorento ( , website: www.sorento.dk), Kenneth Sorento Film & Photography

The media team was invited on board to cover the expedition and science as independent observers. During the cruise, Kenneth Sorento and Martin Breum implemented joint as well as individual projects. The team brought its own equipment, including an Iridium satellite connection for transmitting telephone calls and data. The main media project was to gather interviews and other video material for a 30-minute TV documentary on the Continental Shelf Project of the Kingdom of Denmark.

Kenneth Sorento (right) and Martin Breum at the North Pole 22 August 2012

Kenneth Sorento (right) and Martin Breum at the North Pole 22 August 2012.
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On August 22, 2012 at 21:43 (UTC) Oden reached the North Pole

On August 22, 2012 at 21:43 (UTC) Oden reached the North Pole for the 7th time and the 4th time on its own. The arrival at the North Pole was celebrated by raising the flags of the countries represented onboard Oden. After a glass of sparkling wine on the bridge and a group photo on the sea ice in front of Oden, the ship continued its scientific program (Photo: Björn Eriksson).
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