Time series of near-bottom currents and particle fluxes from Ocean Bottom Moorings in the NE equatorial Pacific

2020 ◽  
Author(s):  
Martina Hollstein ◽  
Annemiek Vink ◽  
Katja Schmidt ◽  
Niko Lahajnar ◽  
Andreas Lückge ◽  
...  
Keyword(s):  
Time Series ◽  
Deep Sea ◽  
Equatorial Pacific ◽  
Series Data ◽  
Bottom Current ◽  
Ocean Bottom ◽  
Mining Activities ◽  
Current Regime ◽  
Polymetallic Nodules ◽  
Particle Fluxes

<p>The globally increasing demand for metals and rare earth elements has raised the interest for potential mining of deep-sea mineral resources such as polymetallic nodules. One important field of polymetallic nodules is located within the Clarion-Clipperton Fracture Zone (CCZ) in the northeastern equatorial Pacific. To date, the International Seabed Authority (ISA) has granted 25 licenses for the exploration of polymetallic nodules in the CCZ. However, the impact of potential future mining activities on the deep-sea environment is only insufficiently known. To assess the environmental impacts of potential future mining activities, a nodule pre-prototype collector test is scheduled to occur in the German license area within the CCZ in autumn 2020, and will be accompanied by an extensive environmental monitoring program (joint effort between BGR and the European research project JPI-Oceans “MiningImpact2”). However, to assess the environmental impact of mining activities, for example due to the development of an operational sediment plume on the seafloor, prior knowledge on the bottom current regime and variability of particle flux and composition within the CCZ under natural conditions is a prerequisite. In order to analyze the bottom current regime and background particle fluxes, BGR deployed Ocean Bottom Moorings (OBM) equipped with current and turbidity meters (4 years between 2013 and 2019), and a sediment trap (2018-2019). Here, we present preliminary results and analyses of these oceanographic and sedimentological time-series data, and compare the results with other available information deriving from the region.</p>

Characteristics of Current-Induced Harmonic Tremor Signals in Ocean-Bottom Seismometer Records

2021 ◽  
Author(s):  
David Essing ◽  
Vera Schlindwein ◽  
Mechita C. Schmidt-Aursch ◽  
Celine Hadziioannou ◽  
Simon C. Stähler
Keyword(s):  
Time Series ◽  
Fundamental Frequency ◽  
Volcanic Tremor ◽  
Mode Locking ◽  
Spectral Amplitude ◽  
Bottom Current ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Natural Sources ◽  
Bottom Currents

Abstract Long-lasting harmonic tremor signals are frequently observed in spectrograms of seismological data. Natural sources, such as volcanoes and icebergs, or artificial sources, such as ships and helicopters, produce very similar harmonic tremor episodes. Ocean-bottom seismometer (OBS) records may additionally be contaminated by tremor induced by ocean-bottom currents acting on the OBS structure. This harmonic tremor noise may severely hinder earthquake detection and can be misinterpreted as volcanic tremor. In a 160-km-long network of 27 OBSs deployed for 1 yr along the Knipovich ridge in the Greenland Sea, harmonic tremor was widely observed away from natural sources such as volcanoes. Based on this network, we present a systematic analysis of the characteristics of hydrodynamically induced harmonic tremor in OBS records to make it distinguishable from natural tremor sources and reveal its generation processes. We apply an algorithm that detects harmonic tremor and extracts time series of its fundamental frequency and spectral amplitude. Tremor episodes typically occur twice per day, starting with fundamental frequencies of 0.5–1.0 Hz, and show three distinct stages that are characterized by frequency-gliding, mode-locking, and large spectral amplitudes, respectively. We propose that ocean-bottom currents larger than ∼5  cm/s cause rhythmical Karman vortex shedding around protruding structures of the OBS and excite eigenvibrations. Head-buoy strumming is the most likely source of the dominant tremor signal, whereas a distinctly different tremor signal with a fundamental frequency ∼6  Hz may be related to eigenvibrations of the radio antenna. Ocean-bottom current velocities reconstructed from the fundamental tremor frequency and from cross correlation of tremor time series between stations match observed average current velocities of 14–20  cm/s in this region. The tremor signal periodicity shows the same tidal constituents as the forcing ocean-bottom currents, which is a further evidence of the hydrodynamic nature of the tremor.

Activities of Musan Mine observed by Sentinel-1 Coherence Imagery

2020 ◽  
Author(s):  
Jihyun Moon ◽  
Heejeong Seo ◽  
Hoonyol Lee
Keyword(s):  
Time Series ◽  
Satellite Images ◽  
European Space Agency ◽  
Open Pit Mine ◽  
Mining Activity ◽  
Open Pit ◽  
Open Pit Mining ◽  
Series Data ◽  
Mining Activities ◽  
Mining Site

<p>Musan mine in North Korea is the largest open-pit iron mine in Asia with the proved reserves of about 2.06 billion tons and more than 9 square kilometers. Open-pit mining is one of the surface mining technique extracting minerals from the surface. Vegetation is rarely distributed at the mining site because the topsoil is removed and the ore is mined directly from the surface. Therefore, it is effective to observe surface displacement at the mining site using Interferometric Synthetic Aperture Radar (InSAR) technology. InSAR coherence detects random surface change that measures the activity or stability of the interferometric phase of InSAR data. High coherence will be maintained on the surface where there is no movement and only surface scattering. On the other hand, the surface where there is a lot of movement and volumetric scattering has low coherence value. Therefore, using 12-days InSAR coherence images from Sentinel-1 satellites, for example, it is possible to analyze how active the open-pit mine is during the 12 days. Sentinel-1A satellite images were acquired from June 11, 2015 to May 24, 2016, followed by Sentine-1B satellite images from September 27, 2016 to April 21, 2019. A total of 102 SAR images were downloaded from European Space Agency (ESA) portal. There is a gap between May 24 and September 27, 2016 due to the transition of the data acquisition plan. Over 100 12-days coherence data were obtained by applying InSAR. Stable spots and target spots were selected through average and standard deviation of the entire coherence time series data. Coherence values include not only the mining activity but also the effects of perpendicular baseline, temporal baseline, and weather. Therefore, NDAI (Normalized Difference Activity Index) was newly defined to remove the noise and only the coherence value due to the influence of the mining activity was extracted. The degree of activities can be observed by the time series coherence and NDAI images. This study needs other references related to mining activities in order to analyze the mining activities in more detail. This method can be applied to other open-pit mine.</p>

Impact of simulated deep-sea polymetallic nodule mining on sediment and pore-water geochemistry in prospective mining areas in the NE Pacific Ocean

2020 ◽  
Author(s):  
Jessica Volz ◽  
Laura Haffert ◽  
Matthias Haeckel ◽  
Andrea Koschinsky ◽  
Sabine Kasten
Keyword(s):  
Steady State ◽  
Pacific Ocean ◽  
Deep Sea ◽  
Surface Sediments ◽  
Small Scale ◽  
Mining Activities ◽  
Mining Equipment ◽  
Geochemical Conditions ◽  
Polymetallic Nodules ◽  
Ne Pacific

<p>Industrial-scale harvesting of deep-sea mineral resources, such as polymetallic nodules, is likely to have severe consequences for the natural environment. However, the effects of mining activities on deep‑sea ecosystems, sediment geochemistry and element fluxes are still poorly understood. Predicting the environmental impact is challenging due to the scarcity of environmental baseline studies and the lack of mining trials with industrial mining equipment in the deep sea. Thus, currently we have to rely on small-scale disturbances simulating deep-sea mining activities as a first-order approximation to study the expected impacts on the abyssal environment and ecosystem.</p><p>We have investigated surface sediments in disturbance tracks of seven small-scale benthic impact experiments, which have been performed in four European contract areas for the exploration of polymetallic nodules in the Clarion-Clipperton Zone (CCZ) in the NE Pacific Ocean. These small-scale disturbance experiments were performed 1 day to 37 years prior to our sampling program in the German, Polish, Belgian and French contract areas using different disturbance devices, such as dredges and epibenthic sledges. We show that the depth distribution of solid-phase Mn in the upper 20 cm of the sediments in the CCZ provides a reliable tool for the determination of the disturbance depth. We found that the upper 5–15 cm of the sediments were removed during various small‑scale disturbance experiments in the different contract areas. Transient transport‑reaction modelling for the Polish and German contract areas reveals that the removal of the surface sediments is associated with the loss of reactive labile organic carbon. As a result, oxygen consumption rates decrease significantly after the removal of the surface sediments, and consequently, oxygen penetrates up to tenfold deeper into the sediments inhibiting denitrification and Mn(IV) reduction. Our model results show that the return to steady state geochemical conditions after the disturbance is controlled by diffusion until the reactive labile TOC fraction in the surface sediments is partly re‑established and the biogeochemical processes commence. While the re-establishment of bioturbation is essential, steady state geochemical conditions are ultimately controlled by the burial rate of organic matter. Hence, under current depositional conditions, new steady state geochemical conditions in the sediments of the CCZ are reached only on a millennium-scale even for these small-scale disturbances simulating deep-sea mining activities.</p>

scholarly journals Impact of small-scale disturbances on geochemical conditions, biogeochemical processes and element fluxes in surface sediments of the eastern Clarion–Clipperton Zone, Pacific Ocean

2020 ◽  
Vol 17 (4) ◽  
pp. 1113-1131 ◽  
Author(s):  
Jessica B. Volz ◽  
Laura Haffert ◽  
Matthias Haeckel ◽  
Andrea Koschinsky ◽  
Sabine Kasten
Keyword(s):  
Steady State ◽  
Environmental Impact ◽  
Deep Sea ◽  
Surface Sediments ◽  
Small Scale ◽  
Mining Activities ◽  
Biogeochemical Processes ◽  
Geochemical Conditions ◽  
Element Fluxes ◽  
Polymetallic Nodules

Abstract. The thriving interest in harvesting deep-sea mineral resources, such as polymetallic nodules, calls for environmental impact studies and, ultimately, for regulations for environmental protection. Industrial-scale deep-sea mining of polymetallic nodules most likely has severe consequences for the natural environment. However, the effects of mining activities on deep-sea ecosystems, sediment geochemistry and element fluxes are still poorly understood. Predicting the environmental impact is challenging due to the scarcity of environmental baseline studies as well as the lack of mining trials with industrial mining equipment in the deep sea. Thus, currently we have to rely on small-scale disturbances simulating deep-sea mining activities as a first-order approximation to study the expected impacts on the abyssal environment. Here, we investigate surface sediments in disturbance tracks of seven small-scale benthic impact experiments, which have been performed in four European contract areas for the exploration of polymetallic nodules in the Clarion–Clipperton Zone (CCZ) in the NE Pacific. These small-scale disturbance experiments were performed 1 d to 37 years prior to our sampling program in the German, Polish, Belgian and French contract areas using different disturbance devices. We show that the depth distribution of solid-phase Mn in the upper 20 cm of the sediments in the CCZ provides a reliable tool for the determination of the disturbance depth, which has been proposed in a previous study from the SE Pacific (Paul et al., 2018). We found that the upper 5–15 cm of the sediments was removed during various small-scale disturbance experiments in the different exploration contract areas. Transient transport-reaction modeling for the Polish and German contract areas reveals that the removal of the surface sediments is associated with the loss of the reactive labile total organic carbon (TOC) fraction. As a result, oxygen consumption rates decrease significantly after the removal of the surface sediments, and, consequently, oxygen penetrates up to 10-fold deeper into the sediments, inhibiting denitrification and Mn(IV) reduction. Our model results show that the return to steady-state geochemical conditions after the disturbance is controlled by diffusion until the reactive labile TOC fraction in the surface sediments is partly re-established and the biogeochemical processes commence. While the re-establishment of bioturbation is essential, steady-state geochemical conditions are ultimately controlled by the delivery rate of organic matter to the seafloor. Hence, under current depositional conditions, new steady-state geochemical conditions in the sediments of the CCZ are reached only on a millennium scale even for these small-scale disturbances simulating deep-sea mining activities.

scholarly journals Impact of small-scale disturbances on geochemical conditions, biogeochemical processes and element fluxes in surface sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean

2019 ◽  
Author(s):  
Jessica B. Volz ◽  
Laura Haffert ◽  
Matthias Haeckel ◽  
Andrea Koschinsky ◽  
Sabine Kasten
Keyword(s):  
Environmental Impact ◽  
Deep Sea ◽  
Surface Sediments ◽  
Small Scale ◽  
Mining Activities ◽  
Biogeochemical Processes ◽  
Mining Equipment ◽  
Transport Reaction ◽  
Element Fluxes ◽  
Polymetallic Nodules

Abstract. The thriving interest in harvesting deep-sea mineral resources, such as polymetallic nodules, calls for environmental impact studies, and ultimately, for regulations for environmental protection. Industrial-scale deep-sea mining of polymetallic nodules most likely has severe consequences for the natural environment. However, the effects of mining activities on deep-sea ecosystems, sediment geochemistry and element fluxes are still poorly conceived. Predicting the environmental impact is challenging due to the scarcity of environmental baseline studies as well as the lack of mining trials with industrial mining equipment in the deep sea. Thus, currently we have to rely on small-scale disturbances simulating deep-sea mining activities as a first-order approximation to study the expected impacts on the abyssal environment. Here, we investigate surface sediments in disturbance tracks of seven small-scale benthic impact experiments, which have been performed in four European contract areas for the exploration of polymetallic nodules in the Clarion-Clipperton Zone (CCZ). These small-scale disturbance experiments were performed 1 day to 37 years prior to our sampling program in the German, Polish, Belgian and French contract areas using different disturbance devices. We show that the depth distribution of solid-phase Mn in the upper 20 cm of the sediments in the CCZ provides a reliable tool for the determination of the disturbance depth, which has been proposed in a previous study (Paul et al., 2018). We found that the upper 5–15 cm of the sediments were removed during various small-scale disturbance experiments in the different exploration contract areas. Transient transport-reaction modelling for the Polish and German contract areas reveals that the removal of the surface sediments is associated with the loss of reactive labile organic carbon. As a result, oxygen consumption rates decrease significantly after the removal of the surface sediments, and consequently, oxygen penetrates up to tenfold deeper into the sediments inhibiting denitrification and Mn(IV) reduction. Our model results show that the post-disturbance geochemical re-equilibration is controlled by diffusion until the reactive labile TOC fraction in the surface sediments is partly re-established and the biogeochemical processes commence. While the re-establishment of bioturbation is essential, the geochemical re-equilibration of the sediments is ultimately controlled by the burial rates of organic matter. Hence, under current depositional conditions, the new geochemical equilibrium in the sediments of the CCZ is reached only on a millennia scale even for these small-scale disturbances simulating deep-sea mining activities.

scholarly journals Biodiversity–ecosystem functioning relationships in long-term time series and palaeoecological records: deep sea as a test bed

2016 ◽  
Vol 371 (1694) ◽  
pp. 20150282 ◽  
Author(s):  
Moriaki Yasuhara ◽  
Hideyuki Doi ◽  
Chih-Lin Wei ◽  
Roberto Danovaro ◽  
Sarah E. Myhre
Keyword(s):  
Time Series ◽  
Time Scales ◽  
Time Scale ◽  
Deep Sea ◽  
Ecosystem Functioning ◽  
Time Series Data ◽  
Series Data ◽  
Ecosystem Stability ◽  
Test Bed ◽  
Biodiversity And Ecosystem Functioning

The link between biodiversity and ecosystem functioning (BEF) over long temporal scales is poorly understood. Here, we investigate biological monitoring and palaeoecological records on decadal, centennial and millennial time scales from a BEF framework by using deep sea, soft-sediment environments as a test bed. Results generally show positive BEF relationships, in agreement with BEF studies based on present-day spatial analyses and short-term manipulative experiments. However, the deep-sea BEF relationship is much noisier across longer time scales compared with modern observational studies. We also demonstrate with palaeoecological time-series data that a larger species pool does not enhance ecosystem stability through time, whereas higher abundance as an indicator of higher ecosystem functioning may enhance ecosystem stability. These results suggest that BEF relationships are potentially time scale-dependent. Environmental impacts on biodiversity and ecosystem functioning may be much stronger than biodiversity impacts on ecosystem functioning at long, decadal–millennial, time scales. Longer time scale perspectives, including palaeoecological and ecosystem monitoring data, are critical for predicting future BEF relationships on a rapidly changing planet.

Optimal reorientation of geophysical sensors: A quaternion-based analytical solution

Geophysics ◽  
2015 ◽  
Vol 80 (2) ◽  
pp. F19-F30 ◽  
Author(s):  
Lars Krieger ◽  
Francesco Grigoli
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
A Priori ◽  
Synthetic Data ◽  
Optimal Solution ◽  
Seismic Profile ◽  
Series Data ◽  
Ocean Bottom ◽  
Full Time ◽  
Ocean Bottom Seismometer

One of the most critical problems affecting geophysical data acquisition procedures is related to the misorientation of multicomponent sensors with respect to a common reference system (e.g., geographic north). In many applications, misoriented sensors affect data analysis procedures, leading to errors in results and interpretations. These problems generally occur in applications where the orientation of the sensor cannot be actively controlled and is not known a priori, e.g., geophysical sensors deployed in borehole installations or on the seafloor. We have developed a quaternion-based method for the optimal reorientation of multicomponent geophysical sensors. In contrast to other approaches, we took into account the full time-series record from all sensor components. Therefore, our method could be applied to all time-series data and was not restricted to a certain type of geophysical sensor. Our method allows the robust calculation of relative reorientations between two-component or three-component sensors. By using a reference sensor in an iterative process, this result can be extended to the estimation of absolute sensor orientations. In addition to finding an optimal solution for a full 3D sensor rotation, we have established a rigorous scheme for the estimation of uncertainties of the resulting orientation parameters. We tested the feasibility and applicability of our method using synthetic data examples for a vertical seismic profile and an ocean bottom seismometer array. We noted that the quaternion-based reorientation method is superior to the standard approach of a single-parameter estimation of rotation angles.

Products and Services Available from U.S. NOAA NCEI Archive of Water Level Data

2021 ◽  
Author(s):  
Aaron Sweeney ◽  
George Mungov ◽  
Lindsey Wright
Keyword(s):  
Time Series ◽  
Water Level ◽  
Time Series Data ◽  
Tide Gauge ◽  
Series Data ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Pressure Data ◽  
Level Data ◽  
Water Level Data

<p>The U.S. National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) archives analog and digital coastal water level data and ocean-bottom pressure data, digitizes select analog data, and performs quality-control and tidal analysis of these data.  The analog tide gauge records (marigrams) cover selected tsunami events between 1854 and 1981 observed at stations across the globe.  There are 3,486 high-resolution scanned marigrams in the archive.  The digital tide gauge data, primarily U.S. stations, have been collected at 1-minute sampling since 2008.  The ocean-bottom pressure data have been collected since 1983.  These time-series data are complementary to the maximum wave heights recorded in the NCEI/World Data Service Global Historical Tsunami Database.  With the introduction of visual timeline inventories, our NOAA partners have helped us identify, recover, and backfill gaps in our archive.  All water level data and products are converted to standardized file formats to reduce barriers to re-use. We provide quality-controlled water level data, computed astronomical tides, details on the harmonic tidal analysis results, and spectra to assess the quality of the de-tiding. Researchers use the quality-controlled data to validate tsunami propagation and storm surge models.  Select scanned marigram images are digitized into numerical time-series data by hand-selecting data points along the inked tidal curves. Though automated data point selection capabilities exist, when tested, they did not accurately detect faint traces and consistently failed to correctly select the peak and trough values. Hand-selection ensured that the maximum and minimum values important across water level research would be accurately recorded. From 2016 to 2019, we have digitized 48 of these images, across ten tsunami events, into ready-to-use, digital time-series data.  In the event of a tsunami, we augment our holdings by collecting and processing data from the National Hydrographic Services in the affected regions and from the United Nations Education, Scientific and Cultural Organization Intergovernmental Oceanographic Commission (UNESCO IOC) Sea Level Stations Monitoring Facility. Currently, UNESCO IOC does not process these data. These data products are then made available via Tsunami Event Pages. </p>

Graphical Exploratory Data Analysis for Categorical Longitudinal and Time Series Data

2013 ◽  
Author(s):  
Stephen J. Tueller ◽  
Richard A. Van Dorn ◽  
Georgiy Bobashev ◽  
Barry Eggleston
Keyword(s):  
Time Series ◽  
Data Analysis ◽  
Exploratory Data Analysis ◽  
Time Series Data ◽  
Series Data ◽  
Exploratory Data

Faktor-Faktor Yang Mempengaruhi Nilai Tukar Dollar Amerika Serikat Terhadap Rupiah Tahun 2000–2013

2017 ◽  
Vol 1 (2) ◽  
pp. 177-191
Author(s):  
Rizki Rahma Kusumadewi ◽  
Wahyu Widayat
Keyword(s):  
Time Series ◽  
Exchange Rate ◽  
Money Supply ◽  
Time Series Data ◽  
The United States ◽  
Economic Conditions ◽  
Series Data ◽  
Arch Model ◽  
United States Dollar ◽  
The Exchange Rate

Exchange rate is one tool to measure a country’s economic conditions. The growth of a stable currency value indicates that the country has a relatively good economic conditions or stable. This study has the purpose to analyze the factors that affect the exchange rate of the Indonesian Rupiah against the United States Dollar in the period of 2000-2013. The data used in this study is a secondary data which are time series data, made up of exports, imports, inflation, the BI rate, Gross Domestic Product (GDP), and the money supply (M1) in the quarter base, from first quarter on 2000 to fourth quarter on 2013. Regression model time series data used the ARCH-GARCH with ARCH model selection indicates that the variables that significantly influence the exchange rate are exports, inflation, the central bank rate and the money supply (M1). Whereas import and GDP did not give any influence.

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