| 1. |
- Arellano, Santiago, 1981, et al.
(författare)
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Synoptic analysis of a decade of daily measurements of SO2 emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change
- 2021
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3516 .- 1866-3508. ; 13:3, s. 1167-1188
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Tidskriftsartikel (refereegranskat)abstract
- Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the impact of the emission from sporadic or localized events to persistent or widespread processes of climatic and environmental importance. These observations provide information on volatile budgets on Earth, chemical evolution of magmas, and atmospheric circulation and dynamics. Space-based observations during the last decades have given us a global view of Earth's volcanic emission, particularly of sulfur dioxide (SO2). Although none of the satellite missions were intended to be used for measurement of volcanic gas emission, specially adapted algorithms have produced time-averaged global emission budgets. These have confirmed that tropospheric plumes, produced from persistent degassing of weak sources, dominate the total emission of volcanic SO2. Although space-based observations have provided this global insight into some aspects of Earth's volcanism, it still has important limitations. The magnitude and short-term variability of lower-atmosphere emissions, historically less accessible from space, remain largely uncertain. Operational monitoring of volcanic plumes, at scales relevant for adequate surveillance, has been facilitated through the use of ground-based scanning differential optical absorption spectrometer (ScanDOAS) instruments since the beginning of this century, largely due to the coordinated effort of the Network for Observation of Volcanic and Atmospheric Change (NOVAC). In this study, we present a compilation of results of homogenized post-analysis of measurements of SO2 flux and plume parameters obtained during the period March 2005 to January 2017 of 32 volcanoes in NOVAC. This inventory opens a window into the short-term emission patterns of a diverse set of volcanoes in terms of magma composition, geographical location, magnitude of emission, and style of eruptive activity. We find that passive volcanic degassing is by no means a stationary process in time and that large sub-daily variability is observed in the flux of volcanic gases, which has implications for emission budgets produced using short-term, sporadic observations. The use of a standard evaluation method allows for intercomparison between different volcanoes and between ground- and space-based measurements of the same volcanoes. The emission of several weakly degassing volcanoes, undetected by satellites, is presented for the first time. We also compare our results with those reported in the literature, providing ranges of variability in emission not accessible in the past. The open-access data repository introduced in this article will enable further exploitation of this unique dataset, with a focus on volcanological research, risk assessment, satellite-sensor validation, and improved quantification of the prevalent tropospheric component of global volcanic emission. Datasets for each volcano are made available at https://novac.chalmers.se (last access: 1 October 2020) under the CC-BY 4 license or through the DOI (digital object identifier) links provided in Table 1.
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| 2. |
- Di Muro, A., et al.
(författare)
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Magma degassing at piton de la fournaise volcano
- 2016
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Ingår i: Active Volcanoes of the World. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 2195-3589 .- 2195-7029. ; , s. 203-222
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Since about 1860 AD, magmatic gas release at Piton de la Fournaise volcano is very weak during intra-eruptive phases and essentially occurs during the relatively short-lived eruptions. Recent gas measurements performed during an eruption in October 2010, combined with detailed review of melt and fluid inclusion composition in magmas erupted over the past 50 kyrs, indicate that most PdF eruptions extrude magmas having variably degassed at shallow depth (P < 1 kbar). The average low gas flux results from the low volume of both the magma recharges (from P > 1 kbar) and the shallow magmas, whose fluids are efficiently scrubbed by the hydrothermal system and the water table. Quantification of SO2 fluxes permits to track syn-eruptive magma ascent at shallow level (above sea level). Deeper exsolution of CO2 (below sea level) provides a potential long-term geochemical precursor for the detection of new magma recharges and volcano unrest.
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| 3. |
- Jiguet, Frederic, et al.
(författare)
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Desert crossing strategies of migrant songbirds vary between and within species
- 2019
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Each year, billions of songbirds cross large ecological barriers during their migration. Understanding how they perform this incredible task is crucial to predict how global change may threaten the safety of such journeys. Earlier studies based on radar suggested that most songbirds cross deserts in intermittent flights at high altitude, stopping in the desert during the day, while recent tracking with light loggers suggested diurnal prolongation of nocturnal flights and common non-stop flights for some species. We analyzed light intensity and temperature data obtained from geolocation loggers deployed on 130 individuals of ten migratory songbird species, and show that a large variety of strategies for crossing deserts exists between, but also sometimes within species. Diurnal stopover in the desert is a common strategy in autumn, while most species prolonged some nocturnal flights into the day. Nonstop flights over the desert occurred more frequently in spring than in autumn, and more frequently in foliage gleaners. Temperature recordings suggest that songbirds crossed deserts with flight bouts performed at various altitudes according to species and season, along a gradient ranging from low above ground in autumn to probably >2000 m above ground level, and possibly at higher altitude in spring. High-altitude flights are therefore not the general rule for crossing deserts in migrant songbirds. We conclude that a diversity of migration strategies exists for desert crossing among songbirds, with variations between but also within species.
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| 4. |
- Pfeffer, M. A., et al.
(författare)
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Ground-Based measurements of the 2014-2015 holuhraun volcanic cloud (Iceland)
- 2018
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Ingår i: Geosciences (Switzerland). - : MDPI AG. - 2076-3263. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The 2014-2015 Bárðarbunga fissure eruption at Holuhraun in central Iceland was distinguished by the high emission of gases, in total 9.6 Mt SO 2 , with almost no tephra. This work collates all ground-based measurements of this extraordinary eruption cloud made under particularly challenging conditions: remote location, optically dense cloud with high SO 2 column amounts, low UV intensity, frequent clouds and precipitation, an extensive and hot lava field, developing ramparts, and high-latitude winter conditions. Semi-continuous measurements of SO 2 flux with three scanning DOAS instruments were augmented by car traverses along the ring-road and along the lava. The ratios of other gases/SO 2 were measured by OP-FTIR, MultiGAS, and filter packs. Ratios of SO 2 /HCl = 30-110 and SO 2 /HF = 30-130 show a halogen-poor eruption cloud. Scientists on-site reported extremely minor tephra production during the eruption. OPC and filter packs showed low particle concentrations similar to non-eruption cloud conditions. Three weather radars detected a droplet-rich eruption cloud. Top of eruption cloud heights of 0.3-5.5 km agl were measured with ground-and aircraft-based visual observations, web camera and NicAIR II infrared images, triangulation of scanning DOAS instruments, and the location of SO 2 peaks measured by DOAS traverses. Cloud height and emission rate measurements were critical for initializing gas dispersal simulations for hazard forecasting.
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| 5. |
- Roman, Diana, et al.
(författare)
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Mechanisms of Unrest and Eruption at Persistently Restless Volcanoes: Insights From the 2015 Eruption of Telica Volcano, Nicaragua
- 2019
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Ingår i: Geochemistry, Geophysics, Geosystems. - 1525-2027. ; 20:8, s. 4162-4183
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Tidskriftsartikel (refereegranskat)abstract
- Many of Earth's volcanoes experience well-defined states of “quiescence” and “unrest,” with unrest occasionally culminating in eruption. Some volcanoes, however, experience an unusually protracted (i.e., decades-long) period of noneruptive unrest and are thus categorized as “persistently restless volcanoes” (PRVs). The processes that drive persistently restless volcanism are poorly understood, as our knowledge of PRVs is currently based on a small number of case studies. Here we examine multidisciplinary observations of the 2015 eruptive episode at Telica Volcano, Nicaragua, in the context of its long-term behavior. We suggest that the latter phases of the 2015 eruption were ultimately driven by destabilization of its shallow magma reservoir. Based on previous geodetic-seismic studies of Telica (Geirsson et al., 2014, https://doi.org/10.1016/j.jvolgeores.2013.11.009; Rodgers et al., 2013, https://doi.org/10.1016/j.jvolgeores.2013.08.010 and 2015, https://doi.org/10.1016/j.jvolgeores.2014.11.012) and on multiparameter observations at Telica over a 7-year period, we propose that three distinct states of unrest occur at Telica over decadal timescales: a stable open state involving steady conduit convection and two distinct “unstable” states that may lead to eruptions. In the “weak sealing” state, phreatic explosions result from steady conduit convection underlying a weak seal. In the “destabilized” state, destabilization of the top of the convecting magma in the conduit leads to rapid accumulation of high pressures leading to strong/impulsive phreatomagmatic explosions. Our observations and interpretations suggest that continuous seismic, ground-based deformation, gas emission, and thermal monitoring and interpretation of these data within a paradigm of sustained conduit convection modulated by episodes of sealing and destabilization of shallow magma reservoirs may allow robust forecasting of eruption potential, energy, and duration at Telica and similar PRVs worldwide.
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| 6. |
- van Akkooi, Alexander C. J., et al.
(författare)
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Neoadjuvant Systemic Therapy (NAST) in Patients with Melanoma: Surgical Considerations by the International Neoadjuvant Melanoma Consortium (INMC)
- 2022
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Ingår i: ANNALS OF SURGICAL ONCOLOGY. - : Springer Science and Business Media LLC. - 1068-9265 .- 1534-4681. ; 29:6, s. 3694-3708
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Tidskriftsartikel (refereegranskat)abstract
- Exciting advances in melanoma systemic therapies have presented the opportunity for surgical oncologists and their multidisciplinary colleagues to test the neoadjuvant systemic treatment approach in high-risk, resectable metastatic melanomas. Here we describe the state of the science of neoadjuvant systemic therapy (NAST) for melanoma, focusing on the surgical aspects and the key role of the surgical oncologist in this treatment paradigm. This paper summarizes the past decade of developments in melanoma treatment and the current evidence for NAST in stage III melanoma specifically. Issues of surgical relevance are discussed, including the risk of progression on NAST prior to surgery. Technical aspects, such as the definition of resectability for melanoma and the extent and scope of routine surgery are presented. Other important issues, such as the utility of radiographic response evaluation and method of pathologic response evaluation, are addressed. Surgical complications and perioperative management of NAST related adverse events are considered. The International Neoadjuvant Melanoma Consortium has the goal of harmonizing NAST trials in melanoma to facilitate rapid advances with new approaches, and facilitating the comparison of results across trials evaluating different treatment regimens. Our ultimate goals are to provide definitive proof of the safety and efficacy of NAST in melanoma, sufficient for NAST to become an acceptable standard of care, and to leverage this platform to allow more personalized, biomarker-driven, tailored approaches to subsequent treatment and surveillance.
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