1,720,963 research outputs found
The first evaluation of the FY-3D/MERSI-2 sensor's thermal infrared capabilities for deriving land surface temperature in volcanic regions: a case study of Mount Etna
Get PDFIn November 2017, the China Meteorological Administration launched a new polar orbiting satellite in its Fengyun (FY) series: FY-3D. With its main purpose being the collection of meteorological data, FY-3D featured a comprehensive payload that is equally exploitable by various Earth Science disciplines. One of its sensors, the MEdium Resolution Spectral Imager-2 (MERSI-2), provides visible and infrared imagery at spatial resolutions of 250 - 1000 m. These characteristics make MERSI-2 suitable for volcanological remote sensing and make it comparable to the National Aeronautics and Space Administration's (NASA's) Moderate Resolution Imaging Spectroradiometer (MODIS) sensors which themselves, have been widely used in volcanological applications. This paper evaluates the first clear and near-coincident MODIS - MERSI-2 images of Mount Etna (Italy) during an active volcanic phase in 2019 and in turn, provides the first assessment of MERSI-2's utility in observing volcanic activity in the Thermal InfraRed (TIR). To ensure the comparability of both scenes, data from each were converted to Land Surface Temperature (LST) and comparisons were encouraging, with an r(2) of 0.92, a mean temperature discrepancy of 0.26 K and a root mean squared error of 0.75 K. Having ascertained comparability, we focussed on the absolute temperatures detected at the eruption site, with the highest being 317.3 K and 328.1 K for MODIS and MERSI-2, respectively. The 20 minute gap between the acquisitions is the most likely the cause of this temperature discrepancy, suggesting variations in lava effusion rates and activity were occurring at Mount Etna over such timescales. This study confirms the applicability of MERSI-2 for observing volcanic activity and emphasises the significance of TIR volcanic monitoring and the importance that additional spaceborne platforms might have in reducing temporal gaps between image acquisitions. Given its unique characteristics, future studies should investigate the applicability of MERSI-2 in more varied volcanic settings
Groundwater Level Variations in relation to Volcanic and Seismic Events. New Insights on Mt. Etna, Southern Italy
No full textIn this preliminary study, the response of Etnean groundwater levels (GWL) to seismic and volcanic events between 2003 and 2007 was investigated. This period was characterised by frequent volcanic and seismic activity. Groundwater timeseries were filtered for the effect of meteoric contribution by employing the Cumulative Rainfall Departure (CRD) approach; these were then examined for correlations with volcanic and/or seismic events. Noteworthy variations in GWLs were observed in the proximity of eruptive episodes. These seemed to be consistent with the variation of other parameters such as ground deformation and SO2 emissions previously investigated by other authors, and with the GWL fluctuations preceding the 2001–2002 seismic-volcanic crisis, detected by the Geochemical Monitoring System (GMS–2). Additionally, the variations observed before the phreatomagmatic explosion of January 12th, 2006, were the most evident among the whole examined period. With regard to this latter event, the GWL of wells to the S/SE sector of the volcano displayed a sudden and quasi-simultaneous lowering. These fluctuations commenced in November 2005 and were coincident with a moderate increase in the amplitude of volcanic tremor and mild inflation of the summit of the volcano, as recorded at permanent GPS stations. Less marked results have been obtained in relation to seismic events and it has not been viable to identify recurrent patterns of variation, mainly due to a low resolution of the available data.This work highlights how GWL variations might suggest, from days to months in advance, alterations to the geodynamic equilibrium of the Etnean region, providing evidence of the importance of groundwater monitoring and providing suggestions for future research. We envisage that this work will encourage the implementation of an efficient quantitative groundwater monitoring network which could reveal crucial information in the search for precursor signals
The Capabilities of FY-3D/MERSI-II Sensor to Detect and Quantify Thermal Volcanic Activity: The 2020–2023 Mount Etna Case Study
Get PDFSatellite data provide crucial information to better understand volcanic processes and mitigate associated risks. In recent years, exploiting the growing number of spaceborne polar platforms, several automated volcanic monitoring systems have been developed. These, however, rely on good geometrical and meteorological conditions, as well as on the occurrence of thermally detectable activity at the time of acquisition. A multiplatform approach can thus increase the number of volcanological-suitable scenes, minimise the temporal gap between acquisitions, and provide crucial information on the onset, evolution, and conclusion of both transient and long-lasting volcanic episodes. In this work, we assessed the capabilities of the MEdium Resolution Spectral Imager-II (MERSI-II) sensor aboard the Fengyun-3D (FY-3D) platform to detect and quantify heat flux sourced from volcanic activity. Using the Middle Infrared Observation of Volcanic Activity (MIROVA) algorithm, we processed 3117 MERSI-II scenes of Mount Etna acquired between January 2020 and February 2023. We then compared the Volcanic Radiative Power (VRP, in Watt) timeseries against those obtained by MODIS and VIIRS sensors. The remarkable agreement between the timeseries, both in trends and magnitudes, was corroborated by correlation coefficients (ρ) between 0.93 and 0.95 and coefficients of determination (R2) ranging from 0.79 to 0.84. Integrating the datasets of the three sensors, we examined the effusive eruption of Mount Etna started on 27 November 2022, and estimated a total volume of erupted lava of 8.15 ± 2.44 × 106 m3 with a Mean Output Rate (MOR) of 1.35 ± 0.40 m3 s-1. The reduced temporal gaps between acquisitions revealed that rapid variations in cloud coverage as well as geometrically unfavourable conditions play a major role in thermal volcano monitoring. Evaluating the capabilities of MERSI-II, we also highlight how a multiplatform approach is essential to enhance the efficiency of satellite-based systems for volcanic surveillance
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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