More than ten years of successful operation of the MARUM-MeBo sea bed drilling technology: Highlights of recent scientific drilling campaigns

2020 ◽  
Author(s):  
Tim Freudenthal ◽  
Gerhard Bohrmann ◽  
Karsten Gohl ◽  
Johann Philipp Klages ◽  
Michael Riedel ◽  
...  
Keyword(s):  
Gamma Ray ◽  
P Wave ◽  
The Arctic ◽  
The Black Sea ◽  
Data Systems ◽  
Successful Operation ◽  
Scientific Drilling ◽  
Sea Bed ◽  
Time Period ◽  
Drilling Technology

<p>Over the last two decades sea bed drilling technology has proven to provide a valuable complement to the services of classical drill ships. Especially for shallow drillings up to 200 mbsf and when working in remote areas difficult to access, sea bed drill rigs are a cost-effective alternative. Recent developments especially concerning borehole logging techniques add to the capabilities of sea bed drilling technology.</p><p>The MARUM-MeBo is a robotic drilling system that is developed since 2004 at the MARUM Center for Marine Environmental Sciences at the University of Bremen (Freudenthal and Wefer, 2013). The drill rig is deployed on the sea bed and remotely controlled from the vessel. It is used for core drilling in soft sediments as well as hard rocks in the deep sea. Especially since an upgrade in 2007/2008 for the use of wireline drilling technique, the first-generation drill rig MARUM-MeBo70 with a drilling capacity of about 70 m was successfully deployed on more than 15 research expeditions. Since 2014 the second-generation drill rig MARUM-MeBo200 with an increased drilling capacity of up to 200 m below sea floor is successfully in operation.</p><p>In this presentation we focus on results of three recent drilling campaigns, exemplifying the exploitation of the potential of the sea bed drilling technology:</p><ol><li>In early 2017 the MeBo70 was deployed from the ice breaking vessel RV POLARSTERN on the West Antarctic shelf (Gohl et al., 2017), an area difficult to access by a drill ship. We were able to recover a sedimentary sequence of the upper Cretaceous time period as one of the very few terrigenous records from this time in Antarctica. This sequence indicates that about 92 to 83 Mio years ago at a paleolatitude of about 82°S this area was covered by a temperate coastal rain forest, making any Antarctic ice sheet formation at this time period unlikely (Klages et al., in press).</li> <li>Also, in 2017 the MeBo70 was deployed in the Arctic off Svalbard. Next to coring a temperature probe was used to assess in situ temperatures and local geothermal gradients (Riedel et al. 2018). Combining these temperature data with the porewater geochemistry of the drilled cores Wallmann et al (2018) were able to prove the effect of isostatic rebound after deglaciation on gas hydrate dissociation.</li> <li>In late 2017 the MeBo200 was deployed in the Black Sea. Geophysical borehole log data of P-wave velocity, electrical resistivity, and spectral gamma ray were combined with core-derived physical properties of porosity, magnetic susceptibility, and bulk density and compared with seismic data of the region (Riedel et al., in press). This study shows the potential of core-log seismic integration for shallow drilling campaigns conducted with a sea bed drill rig.</li> </ol><p>References:</p><p>Freudenthal, T and Wefer, G (2013) Geoscientific Instrumentation, Methods and Data Systems, 2(2). 329-337. doi:10.5194/gi-2-329-2013</p><p>Gohl, K, et al. (2017) Geochemistry, Geophysics, Geosystems, 18, 4235–4250. https://doi.org/10.1002/2017GC007081</p><p>Klages, JP et al. (in press) Nature, 2019-10-14805B</p><p>Riedel, M et al. (2018) Geochemistry, Geophysics, Geosystems, 19, 1165–1177. doi:10.1002/2017GC007288</p><p>Riedel, M et al. (in press) Marine and Petroleum Geology, doi.org/10.1016/j.marpetgeo.2019.104192</p><p>Wallmann, K et al. (2018) Nature Communications, 9:83, DOI: 10.1038/s41467-017-02550-9</p><p> </p>

scholarly journals Remote sensing assessment of glacial loss and vegetation change from 1989 to 2016: Pond Inlet, Nunavut

2021 ◽  
Author(s):  
Ruby R. Pennell
Keyword(s):  
Vegetation Change ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Relevant Literature ◽  
Arctic Tundra ◽  
The Arctic ◽  
Landscape Changes ◽  
Storm Events ◽  
Time Period ◽  
Induced Changes

The climate change phenomenon occurring across the globe is having an increasingly alarming effect on Canada’s Arctic. Warming temperatures can have wide spanning impacts ranging from more rain and storm events, to increasing runoff, thawing permafrost, sea ice decline, melting glaciers, ecosystem disruption, and more. The purpose of this MRP was to assess the climate-induced landscape changes, including glacial loss and vegetation change, in Pond Inlet, Nunavut. A time series analysis was performed using the intervals 1989-1997, 1997-2005, and 2005-2016. The two methods for monitoring change were 1) the Normalized Difference Snow Index (NDSI) to detect glacial change, and 2) the Normalized Difference Vegetation Index (NDVI) to detect vegetation change, both utilizing threshold and masking techniques to increase accuracy. It was found that the percent of glacial loss and vegetation change in Pond Inlet had consistently increased throughout each time period. The area of glacial loss grew through each period to a maximum of 376 km2 of glacial loss in the last decade. Similarly, the area of the Arctic tundra that experienced vegetation change increased in each time period to a maximum of 660 km2 in the last decade. This vegetation change was characterized by overall increasing values of NDVI, revealing that many sections of the Arctic tundra in Pond Inlet were increasing in biomass. However, case study analysis revealed pixel clustering around the lower vegetation class thresholds used to classify change, indicating that shifts between these vegetation classes were likely exaggerated. Shifts between the higher vegetation classes were significant, and were what contributed to the most change in the last decade. The observations of higher glacial melt and increases in biomass are occurring in parallel with the increasing temperatures in Pond Inlet. Relevant literature in the Arctic agrees with the findings of this MRP that there are significant trends of glacial loss and vegetation greening and many studies attribute this directly to climate warming. The results of this study provide the necessary background with regards to landscape changes which could be used in future field studies investigating the climate induced changes in Pond Inlet. This study also demonstrates that significant landscape modifications have occurred in the recent decades and there is a strong need for continued research and monitoring of climate induced changes.

scholarly journals Assessing volumetric change distributions and scaling relations of retrogressive thaw slumps across the Arctic

2022 ◽  
Vol 16 (1) ◽  
pp. 1-15
Author(s):  
Philipp Bernhard ◽  
Simon Zwieback ◽  
Nora Bergner ◽  
Irena Hajnsek
Keyword(s):  
Regional Differences ◽  
Scaling Laws ◽  
Remote Sensing Data ◽  
High Arctic ◽  
The Arctic ◽  
Scaling Relations ◽  
Volumetric Change ◽  
Inverse Gamma ◽  
Time Period ◽  
Study Sites

Abstract. Arctic ice-rich permafrost is becoming increasingly vulnerable to terrain-altering thermokarst, and among the most rapid and dramatic of these changes are retrogressive thaw slumps (RTSs). They initiate when ice-rich soils are exposed and thaw, leading to the formation of a steep headwall which retreats during the summer months. The impacts and the distribution and scaling laws governing RTS changes within and between regions are unknown. Using TanDEM-X-derived digital elevation models, we estimated RTS volume and area changes over a 5-year time period from winter 2011/12 to winter 2016/17 and used for the first time probability density functions to describe their distributions. We found that over this time period all 1853 RTSs mobilized a combined volume of 17×106 m3 yr−1, corresponding to a volumetric change density of 77 m3 yr−1 km−2. Our remote sensing data reveal inter-regional differences in mobilized volumes, scaling laws, and terrain controls. The distributions of RTS area and volumetric change rates follow an inverse gamma function with a distinct peak and an exponential decrease for the largest RTSs. We found that the distributions in the high Arctic are shifted towards larger values than at other study sites We observed that the area-to-volume scaling was well described by a power law with an exponent of 1.15 across all study sites; however the individual sites had scaling exponents ranging from 1.05 to 1.37, indicating that regional characteristics need to be taken into account when estimating RTS volumetric changes from area changes. Among the terrain controls on RTS distributions that we examined, which included slope, adjacency to waterbodies, and aspect, the latter showed the greatest but regionally variable association with RTS occurrence. Accounting for the observed regional differences in volumetric change distributions, scaling relations, and terrain controls may enhance the modelling and monitoring of Arctic carbon, nutrient, and sediment cycles.

scholarly journals Study of \(\gamma \)-ray from 4.53 eV p-wave Resonance of 111Cd Using Compound Nuclear Reaction

2021 ◽  
Author(s):  
S. Makise ◽  
S. Endo ◽  
H. Fujioka ◽  
K. Hirota ◽  
K. Ishizaki ◽  
...  
Keyword(s):  
Nuclear Reaction ◽  
Gamma Ray ◽  
P Wave ◽  
Wave Resonance

scholarly journals Gamma spectrometry technique for the determination of residence time in Submarine Groundwater Discharges

2019 ◽  
Vol 18 ◽  
pp. 155
Author(s):  
G. Eleftheriou ◽  
C. Tsabaris ◽  
D. L. Patiris ◽  
E. Androulakaki ◽  
M. Kokkoris ◽  
...  
Keyword(s):  
Residence Time ◽  
Water Samples ◽  
Gamma Ray ◽  
Measuring System ◽  
Gamma Ray Spectrometry ◽  
Reference Source ◽  
Radium Isotopes ◽  
Time Period ◽  
Submarine Groundwater ◽  
Set Up

The evaluation of time period that meteoric water remains in the ground (residence time) before exiting in the open sea can be a valuable information for the submarine groundwater discharges (SGD) in the costal zones. Coastal waters contain elevated dissolved activities of radium isotopes compared to the open ocean, where excess activities are zero. Lately it has been shown by Moore et al., that residence time can be estimated by a model based on radium radioisotopes ratio reduction throughout the coast. However the standard methods for the estimation of radium isotopes concentration in the water are sophisticated, time consuming or require big amount of sample. Hereby, a method based on the direct gamma ray spectrometry of untreated water samples from coastal areas is applied to determine the residence time of the SGD. Efficiency calibration of the spectrometry set up has been performed for two different volumetric sample geometries, using 152Eu/154Eu solution as reference source. In order to ensure the reliability of the method, the background courting rate magnitude and variance through time have been defined for the radioisotopes of interest. Additionally, the minimum detectible activity (MDA) of the measuring system was determined, in Becquerel per cubic meter, as a function of energy in water samples. The developed method was applied and validated for water samples from the submarine spring in Stoupa Bay, southwestern Peloponnesus. The defined residence time varies from 3 to 6 days, being in good agreement with the results of the standard geological pigment-tracer method.

Induced versus natural earthquakes: Search for a seismic discriminant

1980 ◽  
Vol 70 (1) ◽  
pp. 269-281
Author(s):  
William A. Peppin ◽  
Charles G. Bufe
Keyword(s):  
Active Faults ◽  
P Wave ◽  
S Wave ◽  
Spectral Parameters ◽  
San Andreas ◽  
Time Period ◽  
Seismic Stress ◽  
Stress Drops ◽  
Natural Earthquakes ◽  
Steam Production

abstract A sizeable body (150 records) of three-component, wideband (0.2 to 50 Hz) digital seismic data has allowed a direct comparison between earthquakes at The Geysers geothermal area, California and along nearby active faults of the San Andreas system. An attempt has been made to find analog or spectral parameters which would permit discrimination between 12 events within the steam production field and 30 outside it. Results of the study for both classes of events are: (1) seismic moments vary with local magnitude ML as log M0 = (1.06 ± 0.11) ML + 16.9 ± 0.1; (2) the ratio of vertical P-wave to horizontal S-wave spectral corner frequencies is near unity; (3) seismic stress drops are low (1.0 to 10 bars); and (4) focal mechanisms are quite comparable during the time period of this study.

History of the Russian Empire in the context of theoretical and legal analysis (To the 300th anniversary of the Russian Empire)

2021 ◽  
pp. 186
Author(s):  
Nadezhda S. Nizhnik
Keyword(s):  
The United States ◽  
Russian Empire ◽  
The Arctic ◽  
The Black Sea ◽  
Scientific Conference ◽  
Legal Analysis ◽  
The North ◽  
Internal Affairs ◽  
The Russian Empire ◽  
The Baltic

The review of the XVIII International Scientific Conference "State and Law: evolution, current state, development prospects (to the 300th anniversary of the Russian Empire)" was held on April 29-30, 2021 at the St. Petersburg University of the Ministry of Internal Affairs. The Russian Empire existed on the political map of the world from October 22 (November 2), 1721 until the February Revolution and the overthrow of the Monarchy on March 3, 1917. The Russian Empire was the third largest state that ever existed (after the British and Mongolian Empires): It extended to the Arctic Ocean in the north and the Black Sea in the south, to the Baltic Sea in the west and the Pacific Ocean in the east. The Russian Empire was one of the great powers along with Great Britain, France, Prussia (Germany) and Austria-Hungary, and since the second half of the XIX century – also Italy and the United States. The capital of the Russian Empire was St. Petersburg (1721 - 1728), Moscow (1728 - 1732), then again St. Petersburg (1732 - 1917), renamed Petrograd in 1914. Therefore, it is natural that a conference dedicated to the 300th anniversary of the formation of the Russian Empire was held in St. Petersburg, the former imperial capital. The conference was devoted to problems concerning various aspects of the organization and functioning of the state and law, a retrospective analysis of the activities of state bodies in the Russian Empire. The discussion focused on various issues: the character of the Russian Empire as a socio-legal phenomenon and the subject of the legitimate use of state coercion, the development of political and legal thought, the regulatory and legal foundations of the organization and functioning of the Russian state in the XVIII century – at the beginning of the XX century, the characteristics of state bodies as an element of the mechanism of the imperial state in Russia, the organizational and legal bases of the activities of bodies that manage the internal affairs of the Russian Empire, as well as the image of state authorities and officials-representatives of state power.

High-resolution ocean/sea ice/ice shelf simulation of the 79° North Glacier and Zachariae Isstrøm

2021 ◽  
Author(s):  
Claudia Wekerle ◽  
Ralph Timmermann ◽  
Qiang Wang ◽  
Rebecca McPherson
Keyword(s):  
Sea Ice ◽  
Continental Shelf ◽  
Model Performance ◽  
Greenland Ice Sheet ◽  
Atlantic Water ◽  
Ocean Model ◽  
The Arctic ◽  
Ice Shelf ◽  
Time Period ◽  
Mesh Resolution

<p>The 79° North Glacier (79NG) is the largest of the marine terminating glaciers fed by the  Northeast Greenland Ice Stream (NEGIS), which drains around 15% of the Greenland ice sheet. The 79NG is one of the few Greenland glaciers with a floating ice tongue, and is strongly influenced by warm Atlantic Water originating from Fram Strait and carried towards it through a trough system on the Northeast Greenland continental shelf.</p><p>Considering the decrease in thickness of the 79NG and also of the neighboring Zachariae Isstrøm (ZI), we aim to understand the processes that potentially lead to the decay of these glaciers. As a first step we present here an ocean-sea ice simulation which explicitly resolves the cavities of the 79NG and ZI glaciers, applying the Finite-Element Sea ice-Ocean Model (FESOM). We take advantage of the multi-resolution capability of FESOM and locally increase mesh resolution in the vicinity of the 79NG to 700 m. The Northeast Greenland continental shelf is resolved with 3 km, and the Arctic Ocean and Nordic Seas with 4.5 km. The simulation is conducted for the time period 1980 to 2018, using JRA-55 atmospheric reanalysis. Solid and liquid runoff from Greenland is taken from the Bamber et al. 2018 dataset. The flow of warm Atlantic water into the glacier and outflow of meltwater is compared to observational data from measurement campaigns. We further use current and hydrographic data from moorings deployed in Norske Trough to assess the model performance in carrying warm water towards the glacier. This simulation spanning several decades allows us to investigate recent changes in basal melt rates induced by oceanic processes, in particular warm Atlantic Water transport towards the glacier.</p>

Human biogeography and climate change in Siberia and Arctic North America in the fourth and fifth millennia BP

1990 ◽  
Vol 330 (1615) ◽  
pp. 665-670 ◽  
Keyword(s):  
North America ◽  
The Arctic ◽  
Polar Regions ◽  
Before Present ◽  
Yenisei River ◽  
Northeastern Asia ◽  
Time Period ◽  
The Yenisei River ◽  
Historical Relation ◽  
Small Tool

This paper explores the relation between the geographic shifts in prehistoric hunting populations and changes in climate between 4500 and 3000 before present (BP) within the polar regions from the Yenisei River in Siberia to Greenland. We have chosen this time period because major human geographic changes occurred over much of northeastern Asia and northern North America, and because these changes appear to be linked, at least in part, to a palaeoclimatic fluctuations. The cultures under consideration have been termed the Early and Middle Neolithic (Syalakh and Bel’kachi) in Siberia and the Arctic Small Tool Tradition (with such local variants as Denbigh, Independence I, Pre-Dorset, and Sarqaq) in North America. Despite these terminological differences, these groups shared such a close similarity in their technology and adaptive patterns that they must have once shared a direct historical relation.

Cephalopods as prey. IV. Fishes

1996 ◽  
Vol 351 (1343) ◽  
pp. 1067-1081 ◽  
Keyword(s):  
Prey Capture ◽  
The Arctic ◽  
Potential Prey ◽  
Nurse Shark ◽  
Pelagic Fishes ◽  
Important Prey ◽  
Continental Shelves ◽  
Time Period ◽  
Fish Predators ◽  
Predatory Fishes

Predatory fishes that consume cephalopods have broad spectrum diets that include other groups, such as fishes and crustaceans. Extremely few fish predators feed on cephalopods to the virtual exclusion of other prey, although the tawny nurse shark Nebrius ferrugineus and the sicklefin weasel shark Hemigaleus microstoma may be exceptions, and some deep-living spiny dogfish may feed largely on cephalopods when they are available. Cephalopods are rarely taken in estuaries but they become more important prey on continental shelves and squids may be more dominant prey during their spawning aggregations. Cephalopods generally become more important components of the diets of larger predatory fishes, such as sharks, that inhabit the continental slope and rise. They may be important to pelagic fishes, such as swordfish and tunas in some parts of the oceans. Cephalopods are rarely taken by benthic Antarctic fishes but they are important prey of some pelagic fishes in the Arctic. Abundance and size of potential prey is critical, and the behaviour of both predator and potential prey is decisive, in prey choice. Factors such as prey switching with growth, between areas and at different times, have major influences on the diets of predators. There are extremely few studies that obtain rigorous enough data to allow quantitative analysis of the significance of cephalopods (or other prey) in the diets of predatory fishes and even the most comprehensive studies are not predictive because findings relate only to the time period of each study. Nevertheless, cephalopods are important components of most marine food webs and, furthermore, may play an indirect role in facilitating prey capture to secondary predators, and in providing rejecta to benthic scavengers.

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