Topographic model of Greenland (elevation lines in PanMap and ASCII format)

In this paper, a new high-resolution elevation model of Greenland, including the ice sheet as well as the ice free regions, is presented. It is the first published full coverage model, computed with an average resolution of 2 km and providing an unprecedented degree of detail. The topography is modeled from a wide selection of data sources, including satellite radar altimetry from Geosat and ERS 1, airborne radar altimetry and airborne laser altimetry over the ice sheet, and photogrammetric and manual map scannings in the ice free region. The ice sheet model accuracy is evaluated by omitting airborne laser data from the analysis and treating them as ground truth observations. The mean accuracy of the ice sheet elevations is estimated to be 12-13 m, and it is found that on surfaces of a slope between 0.2° and 0.8°, corresponding to approximately 50% of the ice sheet, the model presents a 40% improvement over models based on satellite altimetry alone. On coastal bedrock, the model is compared with stereo triangulated reference points, and it is found that the model accuracy is of the order of 25-35 m in areas covered by stereo photogrammetry scannings and between 200 and 250 m elsewhere.

Gridded bathymetry from multibeam echosounder EM120 data of the cruise M72/4 (2007)

Bathymetry based on data recorded during M72-4 between 25.04.2007 and 11.05.2007 in the Black Sea. This main objective of this cruise was to gain better knowledge of the pathways of methane from their point of formation via potential intermediate deposits to the seafloor in order to understand the mechanisms leading to the submarine discharge of methane-rich fluids. Two regional Black Sea targets have been chosen: The Sorokin Trough, with focused seepage through mud volcanoes, and the Dniepr area where active gas venting occurs from very shallow water depths down to at least 1000 m.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise M84/2, off Kerch and the eastern Crimea (2011)

Bathymetry based on data recorded during M84-2 between 26.02.2011 and 02.04.2011 in the Black Sea. The aim of the cruise was to investigate the gas hydrate distribution in sediments of the Black Sea by using several coring technics. In addition to the coring activities the installed EM122 and the PARASOUND system were used to detect gas emissions in the water column and to map large areas of possible seep sites.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise M84/2, off Georgia (2011)

Bathymetry based on data recorded during M84-2 between 26.02.2011 and 02.04.2011 in the Black Sea. The aim of the cruise was to investigate the gas hydrate distribution in sediments of the Black Sea by using several coring technics. In addition to the coring activities the installed EM122 and the PARASOUND system were used to detect gas emissions in the water column and to map large areas of possible seep sites.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise M84/2, off Samsun (2011)

Bathymetry based on data recorded during M84-2 between 26.02.2011 and 02.04.2011 in the Black Sea. The aim of the cruise was to investigate the gas hydrate distribution in sediments of the Black Sea by using several coring technics. In addition to the coring activities the installed EM122 and the PARASOUND system were used to detect gas emissions in the water column and to map large areas of possible seep sites.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise M84/2, off Eregli (2011)

We investigated gas bubble emissions at the Don-Kuban paleo-fan in the northeastern Black Sea regarding their geological setting, quantities as well as spatial and temporal variabilities during three ship expeditions between 2007 and 2011. About 600 bubble-induced hydroacoustic anomalies in the water column (flares) originating from the seafloor above the gas hydrate stability zone (GHSZ) at ~700 m water depth were found. At about 890 m water depth a hydrocarbon seep area named "Kerch seep area" was newly discovered within the GHSZ. We propose locally domed sediments ('mounds') discovered during ultra-high resolution bathymetric mapping with an autonomous underwater vehicle (AUV) to result from gas hydrate accumulation at shallow depths. In situ measurements indicated spatially limited temperature elevations in the shallow sediment likely induced by upward fluid flow which may confine the local GHSZ to a few meters below the seafloor. As a result, gas bubbles are suspected to migrate into near-surface sediments and to escape the seafloor through small-scale faults. Hydroacoustic surveys revealed that several flares originated from a seafloor area of about 1 km**2 in size. The highest flare disappeared in about 350 m water depth, suggesting that the released methane remains in the water column. A methane flux estimate, combining data from visual quantifications during dives with a remotely operated vehicle (ROV) with results from ship-based hydroacoustic surveys and gas analysis revealed that between 2 and 87 x 10**6 mol CH4 yr-1 escaped into the water column above the Kerch seep area. Our results show that the finding of the Kerch seep area represents a so far underestimated type of hydrocarbon seep, which has to be considered in methane budget calculations.

Gridded bathymetry from multibeam echosounder EM120 data of the cruise MSM15/2 (2011)

Bathymetry based on data recorded during MSM15-2 between 10.05.2010 and 02.06.2010 in the Black Sea. The aim of the cruise was to perform AUV and ROV pre-site surveys of potential drill sites that represent deposits where shallow gas hydrates have already been sampled by gravity and piston coring and where gas emissions to the water column have been detected.

Gridded bathymetry from multibeam echosounder HS-DS2 data of the cruise M52/1 (2002)

Bathymetry based on data recorded during M52-1 between 02.01.2002 and 01.02.2002 in the Black Sea. The cruise was focused on studying the distribution, structure and architecture of gas hydrate deposits in the Black Sea as well as their relationship to fluid migration pathways. While high-resolution geoacoustic investigation tools covering a whole range of frequencies and techniques render detailed images of near-surface gas hydrates and associated fluid migration pathways.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise MSM34/2 (2013)

Bathymetry based on data recorded during MSM34-2 between 27.12.2013 and 18.01.2014 in the Black Sea. The main objective of this cruise was the mapping and imaging of the gas hydrate distribution and gas accumulations as well as possible gas migration pathways. Objectives of Cruise: Gas hydrates have been the focus of scientific and economic interest for the past 15-20 years, mainly because the amount of carbon stored in gas hydrates is much greater than in other carbon reservoirs. Several countries including Japan, Korea and India have launched vast reasearch programmes dedicated to the exploration for gas hydrate resources and ultimately the exploitation of the gas hydrates for methane. The German SUGAR project that is financed the the Ministry of Education and Research (BmBF) and the Ministry of Economics (BmWi) aims at developing technology to exploit gas hydrate resources by injecting and storing CO2 instead of methane in the hydrates. This approach includes techniques to locate and quantify hydrate reservoirs, drill into the reservoir, extract methane from the hydrates by replacing it with CO2, and monitor the thus formed CO2-hydrate reservoir. Numerical modeling has shown that any exploitation of the gas hydrates can only be succesful, if sufficient hydrate resources are present within permeable reservoirs such as sandy or gravelly deposits. The ultimate goal of the SUGAR project being a field test of the technology developed within the project, knowledge of a suitable test site becomes crucial. Within European waters only the Norwegian margin and the Danube deep-sea fan show clear geophysical evidence for large gas hydrate accumulations, but only the Danube deep-sea fan most likely contains gas hydrates within sandy deposits. The main objective of cruise MSM34 therefore is locating and characterising suitable gas hydrate deposits on the Danube deep-sea fan.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise MSM35

The aim of Maria S. MERIAN voyage MSM35 was to conduct marine controlled source electromagnetic (CSEM) measurements in the Danube Delta, Black Sea, to identify suitable gas hydrate deposits for a future MEBO drilling test site for methane production and CO2 sequestration in hydrate form. Marine CSEM is a geophysical exploration method to derive the electrical properties, i.e. resistivity of the seafloor. Gas hydrates and free gas are electrically insulating and replace conductive pore fluid.

Gridded bathymetry from multibeam echosounder EM120 data of the cruise M72/1 (2007)

Bathymetry based on data recorded during M72-1 between 07.02.2007 and 20.02.2007 in the Black Sea. The main focus of the cruise were gas vents and seeps in the north-western Black Sea below 700 m water depth which is the zone of gas hydrate stability. The main target area was the deep Dnepr Canyon west of the Crimea Peninsula where previous investigations had indicated the occurrence of gas seepage.

Gridded bathymetry from multibeam echosounder EM120 data of the cruise M72/2 (2007)

Bathymetry based on data recorded during M72-2 between 23.02.2007 and 13.03.2007 in the Black Sea. The main focus of the cruise was to study the fluxes and turnover of methane and sulphur in the Black Sea hydrocarbon seep systems and investigating the microbial diversity in two contrasting permanently anoxic settings associated with fluid flow and gas seepage: the methane seeps at the shelf break of the Palaeo-Dnepr area and the hydrocarbon seeps of the mud volcanoes in the 2000 m deep Sorokin trough east of Crimea.

Gridded bathymetry from multibeam echosounder ELAC BottomChart MkII data of the cruise POS317/4 (2004)

Bathymetry based on data recorded during POS317-4 between 16.10.2004 and 04.11.2004. This cruise focused on methane seeps off Georgia and Turkey. Different geological settings were studied by using pressurized sampling techniques and remotely operated vehicles (ROVs).