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  • 1
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    High‐Resolution Ps Receiver Function Imaging of the Crust and Mantle Lithosphere Beneath Southern New England and Tectonic Implications (2021)
    In:  Journal of Geophysical Research: Solid Earth
    Details
    Publication Date: 2022-01-10
    Description: Southern New England exhibits diverse geologic features resulting from past tectonic events. These include Proterozoic and early Paleozoic Laurentian units in the west, several Gondwana-derived terranes that accreted during the Paleozoic in the east, and the Mesozoic Hartford Basin in the central part of the region. The Seismic Experiment for Imaging Structure beneath Connecticut (SEISConn) project involved the deployment of a dense array of 15 broadband seismometers across northern Connecticut to investigate the architecture of lithospheric structures beneath this region and interpret how they were created and modified by past tectonic events in the context of surface geology. We carried out P-to-S receiver function analysis on SEISConn data, including both single-station analysis and common conversion point (CCP) stacking. Our images show that the westernmost part of Connecticut has a much deeper Moho than central and eastern Connecticut. The lateral transition is a well-defined, ∼15 km step-like offset of the Moho over a ∼20 km horizontal distance. The Moho step appears near the surface boundary between the Laurentian margin and the Gondwana-derived Moretown terrane. Possible models for its formation include Ordovician underthrusting of Laurentia and/or modification by younger tectonic events. Other prominent features include a strong positive velocity gradient (PVG) beneath the Hartford basin corresponding to the bottom of the sedimentary units, several west-dipping PVGs in the crust and mantle lithosphere that may correspond to relict slabs or shear zones from past subduction episodes, and a negative velocity gradient (NVG) that may correspond to the base of the lithosphere.
    Type: info:eu-repo/semantics/article
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  • 2
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    Losses of Radiation Belt Energetic Particles by Encounters With Four of the Inner Moons of Jupiter (2022)
    In:  Journal of Geophysical Research: Planets
    Details
    Publication Date: 2022-08-05
    Description: Based on an improved model of the moon absorption of Jovian radiation belt particles, we investigate quantitatively and comprehensively the absorption probabilities and particle lifetimes due to encounters with four of the inner moons of Jupiter (Amalthea, Thebe, Io, and Europa) inside L 〈 10. Our results demonstrate that the resultant average lifetimes of energetic protons and electrons vary dramatically between ∼0.1 days and well above 1,000 days, showing a strong dependence on the particle equatorial pitch angle, kinetic energy and moon orbit. The average lifetimes of energetic protons and electrons against moon absorption are shortest for Io (i.e., ∼0.1–10 days) and longest for Thebe (i.e., up to thousands of days), with the lifetimes in between for Europa and Amalthea. Due to the diploe tilt angle absorption effect, the average lifetimes of energetic protons and electrons vary markedly below and above urn:x-wiley:21699097:media:jgre21827:jgre21827-math-0001 = 67°. Overall, the average electron lifetimes exhibit weak pitch angle dependence, but the average proton lifetimes are strongly dependent on equatorial pitch angle. The average lifetimes of energetic protons decrease monotonically and substantially with the kinetic energy, but the average lifetimes of energetic electrons are roughly constant at energies 〈∼10 MeV, increase substantially around the Kepler velocities of the moons (∼10–50 MeV), and decrease quickly at even higher energies. Compared with the averaged electron lifetimes, the average proton lifetimes are longer at energies below a few MeV and shorter at energies above tens of MeV.
    Type: info:eu-repo/semantics/article
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  • 3
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    Pre-Earthquake Ionospheric Perturbation Identification Using CSES Data via Transfer Learning (2022)
    Frontiers Media S.A.
    Details
    Publication Date: 2022-03-21
    Description: During the lithospheric buildup to an earthquake, complex physical changes occur within the earthquake hypocenter. Data pertaining to the changes in the ionosphere may be obtained by satellites, and the analysis of data anomalies can help identify earthquake precursors. In this paper, we present a deep-learning model, SeqNetQuake, that uses data from the first China Seismo-Electromagnetic Satellite (CSES) to identify ionospheric perturbations prior to earthquakes. SeqNetQuake achieves the best performance [F-measure (F1) = 0.6792 and Matthews correlation coefficient (MCC) = 0.427] when directly trained on the CSES dataset with a spatial window centered on the earthquake epicenter with the Dobrovolsky radius and an input sequence length of 20 consecutive observations during night time. We further explore a transferring learning approach, which initially trains the model with the larger Electro-Magnetic Emissions Transmitted from the Earthquake Regions (DEMETER) dataset, and then tunes the model with the CSES dataset. The transfer-learning performance is substantially higher than that of direct learning, yielding a 12% improvement in the F1 score and a 29% improvement in the MCC value. Moreover, we compare the proposed model SeqNetQuake with other five benchmarking classifiers on an independent test set, which shows that SeqNetQuake demonstrates a 64.2% improvement in MCC and approximately a 24.5% improvement in the F1 score over the second-best convolutional neural network model. SeqNetSquake achieves significant improvement in identifying pre-earthquake ionospheric perturbation and improves the performance of earthquake prediction using the CSES data.
    Description: Published
    Description: 779255
    Description: 7T. Variazioni delle caratteristiche crostali e "precursori"
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Seasonality and timing of sea ice mass balance and heat fluxes in the Arctic transpolar drift during 2019–2020 (2022)
    In:  EPIC3Elementa: Science of the Anthropocene, 10(1), ISSN: 2325-1026
    Details
    Publication Date: 2022-07-14
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 5
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    The challenge of unprecedented floods and droughts in risk management (2022)
    In:  EPIC3Nature, 608(7921), pp. 80-86, ISSN: 0028-0836
    Details
    Publication Date: 2022-09-02
    Description: Risk management has reduced vulnerability to floods and droughts globally, yet their impacts are still increasing. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 6
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    Dissolved and particulate carbon and nitrogen data from seawater collected during CCGS John P. Tully cruises in the northeast Pacific Ocean from Vancouver Island to Station P from 2018 to 2020 (2021)
    Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu
    Details
    Publication Date: 2022-10-31
    Description: Dataset: Discrete C and N near Station P
    Description: This dataset includes observations of dissolved and particulate carbon and nitrogen from seawater samples collected during CCGS John P. Tully cruises from 2018 to 2020 in the northeast Pacific Ocean from Vancouver Island to Station P. Associated parameters such as dissolved inorganic carbon (DIC), total alkalinity (TA), and pH were also measured. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/865893
    Description: NSF Division of Ocean Sciences (NSF OCE) OCE-2032754, NSF Division of Ocean Sciences (NSF OCE) OCE-1756932
    Keywords: Particulate carbon ; Particulate nitrogen ; Inorganic carbon ; North Pacific ; Line P ; EXPORTS
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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  • 7
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    Underway pH of seawater sampled during CCGS John P. Tully cruises in the northeast Pacific Ocean from Vancouver Island to Station P from 2019 to 2020 (2021)
    Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu
    Details
    Publication Date: 2022-10-31
    Description: Dataset: Underway pH data near Line P
    Description: The pH (in situ, total scale) of near surface seawater was measured from the CCGS John P. Tully while underway during three Canadian Line P cruises conducted from 2019 through 2020. A prototype instrument, BGC-SUMO (Y. Takeshita, MBARI), was plumbed into the ship's seawater intake line to measure near surface pH while a collocated thermosalinograph measured near surface salinity and temperature from the same flow stream. This dataset provides information on these properties. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/866582
    Description: NSF Division of Ocean Sciences (NSF OCE) OCE-2032754, NSF Division of Ocean Sciences (NSF OCE) OCE-1756932
    Keywords: Underway pH ; Inorganic carbon ; Line P ; EXPORTS
    Repository Name: Woods Hole Open Access Server
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  • 8
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    Closing the oxygen mass balance in shallow coastal ecosystems (2020)
    Wiley
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Long, M. H., Rheuban, J. E., McCorkle, D. C., Burdige, D. J., & Zimmerman, R. C. Closing the oxygen mass balance in shallow coastal ecosystems. Limnology and Oceanography, 64(6), (2019): 2694-2708, doi: 10.1002/lno.11248.
    Description: The oxygen concentration in marine ecosystems is influenced by production and consumption in the water column and fluxes across both the atmosphere–water and benthic–water boundaries. Each of these fluxes has the potential to be significant in shallow ecosystems due to high fluxes and low water volumes. This study evaluated the contributions of these three fluxes to the oxygen budget in two contrasting ecosystems, a Zostera marina (eelgrass) meadow in Virginia, U.S.A., and a coral reef in Bermuda. Benthic oxygen fluxes were evaluated by eddy covariance. Water column oxygen production and consumption were measured using an automated water incubation system. Atmosphere–water oxygen fluxes were estimated by parameterizations based on wind speed or turbulent kinetic energy dissipation rates. We observed significant contributions of both benthic fluxes and water column processes to the oxygen mass balance, despite the often‐assumed dominance of the benthic communities. Water column rates accounted for 45% and 58% of the total oxygen rate, and benthic fluxes accounted for 23% and 39% of the total oxygen rate in the shallow (~ 1.5 m) eelgrass meadow and deeper (~ 7.5 m) reef site, respectively. Atmosphere–water fluxes were a minor component at the deeper reef site (3%) but a major component at the shallow eelgrass meadow (32%), driven by diel changes in the sign and strength of atmosphere–water gradient. When summed, the measured benthic, atmosphere–water, and water column rates predicted, with 85–90% confidence, the observed time rate of change of oxygen in the water column and provided an accurate, high temporal resolution closure of the oxygen mass balance.
    Description: This work was substantially improved by comments from two anonymous reviewers. We thank Victoria Hill, David Ruble, Jeremy Bleakney, and Brian Collister for assistance in the field and the staff of the Bermuda Institute of Ocean Sciences and the Anheuser‐Busch Coastal Research Center for logistical support. This work was supported by NSF OCE grants 1657727 (to M.H.L. and D.C.M.), 1635403 (to R.C.Z. and D.J.B.), and 1633951 (to M.H.L.).
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Selective preservation of coccolith calcite in Ontong-Java Plateau sediments (2020)
    American Geophysical Union
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography and Paleoclimatology, 34, (2019): 2141-2157, doi: 10.1029/2019PA003731.
    Description: Dissolution of calcite in deep ocean sediments, which is required to balance global marine CaCO3 production and burial fluxes, is still a poorly understood process. In order to assess the mechanisms of dissolution in sediments, we analyzed four multicore tops taken along a depth transect on the Ontong‐Java Plateau. These cores were taken directly on the equator, and span water column calcite saturation states from ∼0.93 to ∼0.74, allowing us to assess the effect of dissolution on carbonate sediment composition. The top 2 cm of each multicore was sectioned and sieved to separate coccolith from foraminiferal calcite, and the %CaCO3, δ13C, Δ14C, and Mg/Ca were evaluated. The mass ratio of coccoliths to foraminifera increases by a factor of 3 as a function of water depth, reflecting the preferential dissolution of foraminifera. Carbon isotope (δ13C and Δ14C) data suggest that most dissolution takes place at the sediment‐water interface and primarily affects foraminifera. Mg/Ca analyses indicate that the Mg content of the entire foraminiferal assemblage decreases as a function of dissolution. In contrast, coccolith dissolution takes place within the sediments, rather than at the interface. Together these two processes cause coccoliths to be up to 1,000 radiocarbon years younger than foraminifera from the same depth horizon. Despite this within‐sediment coccolith dissolution flux, sediments below the calcite saturation horizon remain enriched in coccolith calcite. Combined with global seafloor hypsometry and calcium carbonate content, this enrichment suggests that globally, coccoliths may outweigh foraminifera in deep ocean sediments by a factor of 1.8.
    Description: A. V. S. thanks the NOSAMS facility and the WHOI/NOSAMS postdoc scholar program, James Funds, and the Bessette family for funding and support. A. Q. acknowledges Williams College research and travel funds. We thank the Stanley W. Watson Director's Discretionary Fund for the Picarro‐Automate analyzer. We thank Ellen Roosen at the WHOI core repository for help with sample identification and sectioning. Thanks to Gretchen Swarr and the WHOI plasma mass spectrometry facility. Finally, we thank Bill Martin and Wally Broecker for enlightening discussions on dissolution and radiocarbon dating of deep ocean sediments. All data are included as supporting information files and are archived with NOAA's World Data Service for Paleoceanography (WDS Paleo; https://www.ncdc.noaa.gov/paleo/study/28150).
    Description: 2020-05-15
    Repository Name: Woods Hole Open Access Server
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  • 10
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    Automated classification of three-dimensional reconstructions of coral reefs using convolutional neural networks (2020)
    Public Library of Science
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hopkinson, B. M., King, A. C., Owen, D. P., Johnson-Roberson, M., Long, M. H., & Bhandarkar, S. M. Automated classification of three-dimensional reconstructions of coral reefs using convolutional neural networks. PLoS One, 15(3), (2020): e0230671, doi: 10.1371/journal.pone.0230671.
    Description: Coral reefs are biologically diverse and structurally complex ecosystems, which have been severally affected by human actions. Consequently, there is a need for rapid ecological assessment of coral reefs, but current approaches require time consuming manual analysis, either during a dive survey or on images collected during a survey. Reef structural complexity is essential for ecological function but is challenging to measure and often relegated to simple metrics such as rugosity. Recent advances in computer vision and machine learning offer the potential to alleviate some of these limitations. We developed an approach to automatically classify 3D reconstructions of reef sections and assessed the accuracy of this approach. 3D reconstructions of reef sections were generated using commercial Structure-from-Motion software with images extracted from video surveys. To generate a 3D classified map, locations on the 3D reconstruction were mapped back into the original images to extract multiple views of the location. Several approaches were tested to merge information from multiple views of a point into a single classification, all of which used convolutional neural networks to classify or extract features from the images, but differ in the strategy employed for merging information. Approaches to merging information entailed voting, probability averaging, and a learned neural-network layer. All approaches performed similarly achieving overall classification accuracies of ~96% and 〉90% accuracy on most classes. With this high classification accuracy, these approaches are suitable for many ecological applications.
    Description: This study was funded by grants from the Alfred P. Sloan Foundation (BMH, BR2014-049; https://sloan.org), and the National Science Foundation (MHL, OCE-1657727; https://www.nsf.gov). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
    Repository Name: Woods Hole Open Access Server
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