1,720,963 research outputs found
GNSS processing in Northern Italy at hourly sampling rate, gravity, and detection of the Ocean tide loading
No full textOcean tides especially in closed sea areas can deviate significantly from the theoretical
values due to the bathymetry. Even though the amplitudes of the ocean tides in the Mediterranean Sea are relatively small, the availability of the best tidal model is essential for geodetic
and geodynamic applications.
We analyse different types of geodetic techniques to investigate current ocean tidal models
(FES2014b, EOT20, TPOX9-Atlas) for the Adriatic Sea, eventually to further refine the
ocean-tide model for this particular area. The data used are GNSS double difference products at hourly sampling rate obtained from processing with GNSS Bernese software. The
60 stations processed over a one-year timespan are collected from different European networks. Furthermore, we process tide gauge observation along the Adriatic coast. Gravity
data collected from two relative gravimeters located in the Skocjan cave (Slovenia) are used
as a control of the ocean tide models.
By testing two weeks of GNSS data, we discovered a discrepancy in amplitudes and phases for
the horizontal components between the observations and the predicted model for FES2014b,
while the observed vertical component presents good coherence with the model. We believe
that by expanding the timespan interval of observations, investigating other global ocean
loading models and adding gravity data, we should be able to obtain a clearer understanding
of the identified discrepancies.
In a second step, the analysis looks at the detection of non-tidal loading high stance effects present in GNSS and gravity time series, an important condition for the estimation of
accurate rates of the Earth’s crust movement in the studied area
Detection limit to Earthquakes and seamounts of Quantum gravimeter payload combined with satellite-satellite tracking from single GRACE type to multiple couples constellations
No full textAdvancements in space-based gravity observation are poised to undergo a significant
transformation in the coming years, propelled by innovations such as the MAGIC constellation,
featuring a single polar pair GRACE-C, and the enhanced ESA’s NGGM inclined
pair, boasting lower orbit altitudes and drag compensation capabilities. This trajectory is
further bolstered by the potential integration of augmented satellite constellations equipped
with absolute accelerometers utilizing Cold Atom Interferometer technologies. These developments
promise lower spectral noise curves, thereby enabling higher time resolution and a
superior spatial resolution compared to current standards set by GRACE-FO.
Our exploration extends to pioneering applications within the domain of solid earth sciences,
encompassing seismic events, seamount formations, vertical topographic shifts, and
fluid reservoir dynamics, all of which stand to benefit from the forthcoming advancements
in gravity observation from space. While phenomena linked to the earthquake cycle and
postseismic fault movements are effectively monitored on land through SAR and GPS, their
observation in remote oceanic regions remains challenging due to the absence of seismic
waves generated by slow fault movements. We delineate the observable magnitude limits
contingent upon fault mechanisms, depths, and satellite constellations.
Similarly, the detection of seamounts, particularly in remote areas where they may silently
grow, altering underwater bathymetry in uncharted ways, presents a formidable task that
could potentially be addressed through future spaceborne gravity observations (Braitenberg
and Pastorutti, 2024). The vertical topographic movement is documented by GPS and SAR,
leading to a mass change which we compare to competing mass changes as the hydrologic
and glacial mass loss in the Alps and to the detectability levels of the future satellite constellations.
We finally show that in future the isolated gravity signals for the tectonic movements are
complementary to data used in the Copernicus Services of a) Disaster Management and b)
Climate Change Monitoring and are prone to improve the completeness of these Services
Innovative solid Earth applications of future gravity field missions
No full textThe upcoming gravity missions anticipated in the next decade are expected to significantly reduce noise levels compared to current data acquisitions from GRACE and GRACE Follow On. Our objective is to proactively prepare for these future datasets and develop scientific processing tools that can yield innovative applications in solid earth research. These applications have the potential to evolve into community-relevant ser-vices for earth monitoring and exploration.
We specifically focus on key categories such as earthquakes, crustal uplift and subsidence, seamounts, and lithospheric structure. Accurately estimating the gravity field necessitates the formulation of realistic 3D models of density and their temporal changes.
Uplift and subsidence is considered for the Alpine mountain arc, where a lithosphere density model has been formulated (Tadiello & Braitenberg, 2021) imposing vertical movements from measured GNSS rates. The exploration of the lithosphere is tested on a recent 3D density model of Iran (Maurizio et al., 2023) which was inverted from the presently available gravity field integrated with a seismic tomography model. We distinguish crustal and mantle signals and evaluate prospective improvements to detect structures in crust and mantle.
In the context of earthquakes, our focus lies in improving the minimum detectable magnitude, depending on fault plane mechanisms, and detecting post-seismic relaxation. Seamounts pose a unique challenge with limited alternatives for detection, placing gravity detection in a primary role, provided the associated mass changes are sufficiently significant. Therefore, we conduct a review of documented seamount eruptions, estimating the associated mass changes. Particularly intriguing are 'silent' seamounts that grow several hundred meters high without breaking the ocean surface, remaining invisible.
We compare the signals against noise levels of the future gravity missions, including the polar and inclined satellite couples with inter satellite distance measurement, the MAGIC proposal (Daras et al., 2024) and proposals with the payload of quantum technology gradiometers presently under discussion at ESA and NASA.
References
Daras, I., March, G., Pail, R., Hughes, C. W., Braitenberg, C., Güntner, A., Eicker, A., Wouters, B., Heller-Kaikov, B., Pivetta, T., & Pastorutti, A. (2024). Mass-change And Geosciences International Constellation (MAGIC) expected impact on science and applications. Geophysical Journal International, 236(3), 1288–1308. https://doi.org/10.1093/gji/ggad472
Maurizio, G., Braitenberg, C., Sampietro, D., & Capponi, M. (2023). A New Lithospheric Density and Magnetic Susceptibility Model of Iran, Starting From High‐Resolution Seismic Tomography. Journal of Geophysical Research: Solid Earth, 128(12), e2023JB027383. https://doi.org/10.1029/2023JB027383
Tadiello, D., & Braitenberg, C. (2021). Gravity modeling of the Alpine lithosphere affected by magmatism based on seismic tomography. Solid Earth, 12(2), 539–561. https://doi.org/10.5194/se-12-539-202
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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